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* vt: remove superfluous CONFIG_HW_CONSOLELukas Bulwahn2024-01-271-1/+1
| | | | | | | | | | | | | | | | | The config HW_CONSOLE is always identical to the config VT and is not visible in the kernel's build menuconfig. So, CONFIG_HW_CONSOLE is redundant. Replace all references to CONFIG_HW_CONSOLE with CONFIG_VT and remove CONFIG_HW_CONSOLE. Signed-off-by: Lukas Bulwahn <lukas.bulwahn@gmail.com> Reviewed-by: Javier Martinez Canillas <javierm@redhat.com> Acked-by: Dmitry Torokhov <dmitry.torokhov@gmail.com> Reviewed-by: Geert Uytterhoeven <geert@linux-m68k.org> Acked-by: Geert Uytterhoeven <geert@linux-m68k.org> Link: https://lore.kernel.org/r/20240108134102.601-1-lukas.bulwahn@gmail.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: vt: fix up kernel-docJiri Slaby (SUSE)2024-01-271-3/+3
| | | | | | | | | | | | | | | | | | | selection.c and vt.c still uses tabs in the kernel-doc. This misrenders the functions in the output -- sphinx misinterprets the description. So remove these tabs, incl. those around dashes. 'enum' keyword is needed before enum names. Fix that. Superfluous \n after the comments are also removed. They are not completely faulty, but this unifies all the kernel-doc in the files. Finally fix up the cross references. Signed-off-by: "Jiri Slaby (SUSE)" <jirislaby@kernel.org> Reviewed-by: Randy Dunlap <rdunlap@infradead.org> Tested-by: Helge Deller <deller@gmx.de> # parisc STI console Link: https://lore.kernel.org/r/20240122110401.7289-47-jirislaby@kernel.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: vt: document the rest of struct conswJiri Slaby (SUSE)2024-01-271-9/+25
| | | | | | | | | | There are still members of struct consw which are not documented yet. Fix that up, so we can generate kernel-doc for that struct. Signed-off-by: "Jiri Slaby (SUSE)" <jirislaby@kernel.org> Tested-by: Helge Deller <deller@gmx.de> # parisc STI console Link: https://lore.kernel.org/r/20240122110401.7289-46-jirislaby@kernel.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: vt: remove unused consw::con_flush_scrollback()Jiri Slaby (SUSE)2024-01-271-4/+0
| | | | | | | | | | consw::con_flush_scrollback() is unused since commit 973c096f6a85 (vgacon: remove software scrollback support). Drop it. Signed-off-by: "Jiri Slaby (SUSE)" <jirislaby@kernel.org> Tested-by: Helge Deller <deller@gmx.de> # parisc STI console Link: https://lore.kernel.org/r/20240122110401.7289-45-jirislaby@kernel.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: vt: remove consw::con_getxy()Jiri Slaby (SUSE)2024-01-271-2/+0
| | | | | | | | | After the previous patch, nobody sets that hook. So drop it completely. Signed-off-by: "Jiri Slaby (SUSE)" <jirislaby@kernel.org> Tested-by: Helge Deller <deller@gmx.de> # parisc STI console Link: https://lore.kernel.org/r/20240122110401.7289-44-jirislaby@kernel.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: vt: remove consw::con_screen_pos()Jiri Slaby (SUSE)2024-01-271-1/+0
| | | | | | | | | After the previous patch, nobody sets that hook. So drop it completely. Signed-off-by: "Jiri Slaby (SUSE)" <jirislaby@kernel.org> Tested-by: Helge Deller <deller@gmx.de> # parisc STI console Link: https://lore.kernel.org/r/20240122110401.7289-41-jirislaby@kernel.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: vt: change consw::con_set_origin() return typeJiri Slaby (SUSE)2024-01-271-1/+4
| | | | | | | | | | | | | | | | | The return value of consw::con_set_origin() is only true/false, meaining if vc->vc_origin is set to vc->vc_screenbuf or not. So switch the type and returned values accordingly. And document the hook. Signed-off-by: "Jiri Slaby (SUSE)" <jirislaby@kernel.org> Cc: Helge Deller <deller@gmx.de> Cc: linux-fbdev@vger.kernel.org Cc: dri-devel@lists.freedesktop.org Tested-by: Helge Deller <deller@gmx.de> # parisc STI console Link: https://lore.kernel.org/r/20240122110401.7289-39-jirislaby@kernel.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: vt: make consw::con_font_default()'s name constJiri Slaby (SUSE)2024-01-271-1/+1
| | | | | | | | | | | | | | | It's a name after all and that is not supposed to be changed. So make it const to make this obvious. Signed-off-by: "Jiri Slaby (SUSE)" <jirislaby@kernel.org> Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com> Cc: Daniel Vetter <daniel@ffwll.ch> Cc: linux-fbdev@vger.kernel.org Cc: dri-devel@lists.freedesktop.org Cc: linux-parisc@vger.kernel.org Tested-by: Helge Deller <deller@gmx.de> # parisc STI console Link: https://lore.kernel.org/r/20240122110401.7289-38-jirislaby@kernel.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: vt: make font of consw::con_font_set() constJiri Slaby (SUSE)2024-01-271-2/+3
| | | | | | | | | | | | | | | | Provided the font parameter of consw::con_font_set() is not supposed to be changed, make it const. Signed-off-by: "Jiri Slaby (SUSE)" <jirislaby@kernel.org> Cc: Helge Deller <deller@gmx.de> Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com> Cc: Daniel Vetter <daniel@ffwll.ch> Cc: linux-fbdev@vger.kernel.org Cc: dri-devel@lists.freedesktop.org Cc: linux-parisc@vger.kernel.org Tested-by: Helge Deller <deller@gmx.de> # parisc STI console Link: https://lore.kernel.org/r/20240122110401.7289-37-jirislaby@kernel.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: vt: make types around consw::con_blank() boolJiri Slaby (SUSE)2024-01-271-2/+5
| | | | | | | | | | | | | | | | | | | Both the mode_switch parameter and the return value (a redraw needed) are true/false. So switch them to bool, so that users won't return -Eerrors or anything else. And document the hook. Signed-off-by: "Jiri Slaby (SUSE)" <jirislaby@kernel.org> Cc: Helge Deller <deller@gmx.de> Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com> Cc: Daniel Vetter <daniel@ffwll.ch> Cc: linux-fbdev@vger.kernel.org Cc: dri-devel@lists.freedesktop.org Cc: linux-parisc@vger.kernel.org Tested-by: Helge Deller <deller@gmx.de> # parisc STI console Link: https://lore.kernel.org/r/20240122110401.7289-36-jirislaby@kernel.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: vt: use enum constants for VESA blanking modesJiri Slaby (SUSE)2024-01-271-1/+2
| | | | | | | | | | | | | | | | Use the new enum for VESA constants. This improves type checking in consw::con_blank(). Signed-off-by: "Jiri Slaby (SUSE)" <jirislaby@kernel.org> Cc: Helge Deller <deller@gmx.de> Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com> Cc: Daniel Vetter <daniel@ffwll.ch> Cc: linux-fbdev@vger.kernel.org Cc: dri-devel@lists.freedesktop.org Cc: linux-parisc@vger.kernel.org Tested-by: Helge Deller <deller@gmx.de> # parisc STI console Link: https://lore.kernel.org/r/20240122110401.7289-35-jirislaby@kernel.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: vt: define a common enum for VESA blanking constantsJiri Slaby (SUSE)2024-01-271-6/+1
| | | | | | | | | | | | | | | | | | | | | | There are currently two places with VESA blanking constants definitions: fb.h and console.h. Extract/unify the two to a separate header (vesa.h). Given the fb's is in an uapi header, create the common header in uapi too. Note that instead of macros, an enum (vesa_blank_mode) is created. But the macros are kept too (they now expand to the enum constants), just in case someone in userspace performs some #ifdeffery. Signed-off-by: "Jiri Slaby (SUSE)" <jirislaby@kernel.org> Cc: Helge Deller <deller@gmx.de> Cc: linux-kernel@vger.kernel.org Cc: linux-fbdev@vger.kernel.org Cc: dri-devel@lists.freedesktop.org Cc: Thomas Zimmermann <tzimmermann@suse.de> Tested-by: Helge Deller <deller@gmx.de> # parisc STI console Link: https://lore.kernel.org/r/20240122110401.7289-33-jirislaby@kernel.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: vt: make consw::con_switch() return a boolJiri Slaby (SUSE)2024-01-271-1/+3
| | | | | | | | | | | | | | | | | | | The non-zero (true) return value from consw::con_switch() means a redraw is needed. So make this return type a bool explicitly instead of int. The latter might imply that -Eerrors are expected. They are not. And document the hook. Signed-off-by: "Jiri Slaby (SUSE)" <jirislaby@kernel.org> Cc: Helge Deller <deller@gmx.de> Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com> Cc: Daniel Vetter <daniel@ffwll.ch> Cc: linux-fbdev@vger.kernel.org Cc: dri-devel@lists.freedesktop.org Cc: linux-parisc@vger.kernel.org Tested-by: Helge Deller <deller@gmx.de> # parisc STI console Link: https://lore.kernel.org/r/20240122110401.7289-31-jirislaby@kernel.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: vt: remove CM_* constantsJiri Slaby (SUSE)2024-01-271-6/+2
| | | | | | | | | | | | | | | | | | | | | | There is no difference between CM_MOVE and CM_DRAW. Either of them enables the cursor. CM_ERASE then disables cursor. So get rid of all of them and use simple "bool enable". Note that this propagates down to the fbcon code. And document the hook. Signed-off-by: "Jiri Slaby (SUSE)" <jirislaby@kernel.org> Cc: Helge Deller <deller@gmx.de> Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com> Cc: Daniel Vetter <daniel@ffwll.ch> Cc: linux-fbdev@vger.kernel.org Cc: dri-devel@lists.freedesktop.org Cc: linux-parisc@vger.kernel.org Tested-by: Helge Deller <deller@gmx.de> # parisc STI console Link: https://lore.kernel.org/r/20240122110401.7289-30-jirislaby@kernel.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: vt: sanitize consw::con_putcs() parametersJiri Slaby (SUSE)2024-01-271-2/+4
| | | | | | | | | | | | | Similar to con_putc() in the previous patch: * make the pointer to charattr a pointer to u16, and * make x, y, and count unsigned as they are strictly non-negative. And again, document that hook. Signed-off-by: "Jiri Slaby (SUSE)" <jirislaby@kernel.org> Tested-by: Helge Deller <deller@gmx.de> # parisc STI console Link: https://lore.kernel.org/r/20240122110401.7289-27-jirislaby@kernel.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: vt: sanitize consw::con_putc() parametersJiri Slaby (SUSE)2024-01-271-1/+4
| | | | | | | | | | | | | | | | | Make parameters of consw::con_putc() saner: * x and y are unsigned now, as they cannot be negative, and * ca is made u16, as it is composed of two 8bit values (character and attribute). See the con_putcs() hook, u16/ushort is worked on there. And document the hook. Signed-off-by: "Jiri Slaby (SUSE)" <jirislaby@kernel.org> Cc: Helge Deller <deller@gmx.de> Cc: linux-fbdev@vger.kernel.org Cc: dri-devel@lists.freedesktop.org Tested-by: Helge Deller <deller@gmx.de> # parisc STI console Link: https://lore.kernel.org/r/20240122110401.7289-26-jirislaby@kernel.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: vt: sanitize arguments of consw::con_clear()Jiri Slaby (SUSE)2024-01-271-2/+3
| | | | | | | | | | | | | | | | | | | | | | | | | In consw::con_clear(): * Height is always 1, so drop it. * Offsets and width are always unsigned values, so re-type them as such. This needs a new __fbcon_clear() in the fbcon code to still handle height which might not be 1 when called internally. Note that tests for negative count/width are left in place -- they are taken care of in the next patches. And document the hook. Signed-off-by: "Jiri Slaby (SUSE)" <jirislaby@kernel.org> Cc: Helge Deller <deller@gmx.de> Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com> Cc: Daniel Vetter <daniel@ffwll.ch> Cc: linux-fbdev@vger.kernel.org Cc: dri-devel@lists.freedesktop.org Cc: linux-parisc@vger.kernel.org Tested-by: Helge Deller <deller@gmx.de> # parisc STI console Link: https://lore.kernel.org/r/20240122110401.7289-22-jirislaby@kernel.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: vt: make init parameter of consw::con_init() a boolJiri Slaby (SUSE)2024-01-271-1/+3
| | | | | | | | | | | | | | | | | | | The 'init' parameter of consw::con_init() is true for the first call of the hook on a particular console. So make the parameter a bool. And document the hook. Signed-off-by: "Jiri Slaby (SUSE)" <jirislaby@kernel.org> Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be> Cc: Helge Deller <deller@gmx.de> Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com> Cc: Daniel Vetter <daniel@ffwll.ch> Cc: linux-fbdev@vger.kernel.org Cc: dri-devel@lists.freedesktop.org Cc: linux-parisc@vger.kernel.org Tested-by: Helge Deller <deller@gmx.de> # parisc STI console Link: https://lore.kernel.org/r/20240122110401.7289-21-jirislaby@kernel.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: vt: make consw::con_debug_*() return voidJiri Slaby (SUSE)2024-01-271-12/+6
| | | | | | | | | | | | | | | The return value of con_debug_enter() and con_debug_leave() is ignored on many fronts. So just don't propagate errors (the current implementations return 0 anyway) and make the return type a void. Signed-off-by: "Jiri Slaby (SUSE)" <jirislaby@kernel.org> Cc: Daniel Vetter <daniel@ffwll.ch> Cc: Helge Deller <deller@gmx.de> Cc: linux-fbdev@vger.kernel.org Cc: dri-devel@lists.freedesktop.org Tested-by: Helge Deller <deller@gmx.de> # parisc STI console Link: https://lore.kernel.org/r/20240122110401.7289-20-jirislaby@kernel.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: vt: pass vc_resize_user as a parameterJiri Slaby (SUSE)2024-01-271-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | It is pretty unfortunate to set vc_data::vc_resize_user in two callers of vc_do_resize(). vc_resize_user is immediately reset there (while remembering it). So instead of this back and forth, pass 'from_user' as a parameter. Notes on 'int user': * The name changes from 'user' to 'from_user' on some places to be consistent. * The type is bool now as 'int user' might evoke user's uid or whatever. Provided vc_resize() is called on many places and they need not to care about this parameter, its prototype is kept unchanged. Instead, it is now an inline calling a new __vc_resize() which implements the above. This patch makes the situation much more obvious. Signed-off-by: "Jiri Slaby (SUSE)" <jirislaby@kernel.org> Cc: Helge Deller <deller@gmx.de> Cc: Daniel Vetter <daniel@ffwll.ch> Cc: linux-fbdev@vger.kernel.org Cc: dri-devel@lists.freedesktop.org Tested-by: Helge Deller <deller@gmx.de> # parisc STI console Link: https://lore.kernel.org/r/20240122110401.7289-8-jirislaby@kernel.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* Merge tag 'tty-6.7-rc1' of ↵Linus Torvalds2023-11-031-1/+8
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty Pull tty and serial updates from Greg KH: "Here is the big set of tty/serial driver changes for 6.7-rc1. Included in here are: - console/vgacon cleanups and removals from Arnd - tty core and n_tty cleanups from Jiri - lots of 8250 driver updates and cleanups - sc16is7xx serial driver updates - dt binding updates - first set of port lock wrapers from Thomas for the printk fixes coming in future releases - other small serial and tty core cleanups and updates All of these have been in linux-next for a while with no reported issues" * tag 'tty-6.7-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty: (193 commits) serdev: Replace custom code with device_match_acpi_handle() serdev: Simplify devm_serdev_device_open() function serdev: Make use of device_set_node() tty: n_gsm: add copyright Siemens Mobility GmbH tty: n_gsm: fix race condition in status line change on dead connections serial: core: Fix runtime PM handling for pending tx vgacon: fix mips/sibyte build regression dt-bindings: serial: drop unsupported samsung bindings tty: serial: samsung: drop earlycon support for unsupported platforms tty: 8250: Add note for PX-835 tty: 8250: Fix IS-200 PCI ID comment tty: 8250: Add Brainboxes Oxford Semiconductor-based quirks tty: 8250: Add support for Intashield IX cards tty: 8250: Add support for additional Brainboxes PX cards tty: 8250: Fix up PX-803/PX-857 tty: 8250: Fix port count of PX-257 tty: 8250: Add support for Intashield IS-100 tty: 8250: Add support for Brainboxes UP cards tty: 8250: Add support for additional Brainboxes UC cards tty: 8250: Remove UC-257 and UC-431 ...
| * printk: Constify name for add_preferred_console()Tony Lindgren2023-10-171-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | While adding a preferred console handling for serial_core for serial port hardware based device addressing, Jiri suggested we constify name for add_preferred_console(). The name gets copied anyways. This allows serial core to add a preferred console using serial drv->dev_name without copying it. Note that constifying options causes changes all over the place because of struct console for match(). Suggested-by: Jiri Slaby <jirislaby@kernel.org> Reviewed-by: Petr Mladek <pmladek@suse.com> Signed-off-by: Tony Lindgren <tony@atomide.com> Link: https://lore.kernel.org/r/20231012064300.50221-2-tony@atomide.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| * printk: Check valid console index for preferred consoleTony Lindgren2023-10-171-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Let's check for valid console index values for preferred console to avoid bogus console index numbers from kernel command line. Let's also return an error for negative index numbers for the preferred console. Unlike for device drivers, a negative index is not valid for the preferred console. Let's also constify idx while at it. Signed-off-by: Tony Lindgren <tony@atomide.com> Link: https://lore.kernel.org/r/20231012064300.50221-1-tony@atomide.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| * vgacon: remove screen_info dependencyArnd Bergmann2023-10-171-0/+7
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The vga console driver is fairly self-contained, and only used by architectures that explicitly initialize the screen_info settings. Chance every instance that picks the vga console by setting conswitchp to call a function instead, and pass a reference to the screen_info there. Reviewed-by: Javier Martinez Canillas <javierm@redhat.com> Acked-by: Khalid Azzi <khalid@gonehiking.org> Acked-by: Helge Deller <deller@gmx.de> Signed-off-by: Arnd Bergmann <arnd@arndb.de> Link: https://lore.kernel.org/r/20231009211845.3136536-6-arnd@kernel.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* | printk: nbcon: Allow drivers to mark unsafe regions and check stateThomas Gleixner2023-09-181-0/+10
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | For the write_atomic callback, the console driver may have unsafe regions that need to be appropriately marked. Provide functions that accept the nbcon_write_context struct to allow for the driver to enter and exit unsafe regions. Also provide a function for drivers to check if they are still the owner of the console. Co-developed-by: John Ogness <john.ogness@linutronix.de> Signed-off-by: John Ogness <john.ogness@linutronix.de> Signed-off-by: Thomas Gleixner (Intel) <tglx@linutronix.de> Reviewed-by: Petr Mladek <pmladek@suse.com> Signed-off-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/20230916192007.608398-9-john.ogness@linutronix.de
* | printk: nbcon: Add emit function and callback function for atomic printingThomas Gleixner2023-09-181-0/+21
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Implement an emit function for nbcon consoles to output printk messages. It utilizes the lockless printk_get_next_message() and console_prepend_dropped() functions to retrieve/build the output message. The emit function includes the required safety points to check for handover/takeover and calls a new write_atomic callback of the console driver to output the message. It also includes proper handling for updating the nbcon console sequence number. A new nbcon_write_context struct is introduced. This is provided to the write_atomic callback and includes only the information necessary for performing atomic writes. Co-developed-by: John Ogness <john.ogness@linutronix.de> Signed-off-by: John Ogness <john.ogness@linutronix.de> Signed-off-by: Thomas Gleixner (Intel) <tglx@linutronix.de> Reviewed-by: Petr Mladek <pmladek@suse.com> Signed-off-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/20230916192007.608398-8-john.ogness@linutronix.de
* | printk: nbcon: Add sequence handlingThomas Gleixner2023-09-181-0/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Add an atomic_long_t field @nbcon_seq to the console struct to store the sequence number for nbcon consoles. For nbcon consoles this will be used instead of the non-atomic @seq field. The new field allows for safe atomic sequence number updates without requiring any locking. On 64bit systems the new field stores the full sequence number. On 32bit systems the new field stores the lower 32 bits of the sequence number, which are expanded to 64bit as needed by folding the values based on the sequence numbers available in the ringbuffer. For 32bit systems, having a 32bit representation in the console is sufficient. If a console ever gets more than 2^31 records behind the ringbuffer then this is the least of the problems. Co-developed-by: John Ogness <john.ogness@linutronix.de> Signed-off-by: John Ogness <john.ogness@linutronix.de> Signed-off-by: Thomas Gleixner (Intel) <tglx@linutronix.de> Signed-off-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/20230916192007.608398-7-john.ogness@linutronix.de
* | printk: nbcon: Add buffer managementThomas Gleixner2023-09-181-0/+7
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | In case of hostile takeovers it must be ensured that the previous owner cannot scribble over the output buffer of the emergency/panic context. This is achieved by: - Adding a global output buffer instance for the panic context. This is the only situation where hostile takeovers can occur and there is always at most 1 panic context. - Allocating an output buffer per non-boot console upon console registration. This buffer is used by the console owner when not in panic context. (For boot consoles, the existing shared global legacy output buffer is used instead. Boot console printing will be synchronized with legacy console printing.) - Choosing the appropriate buffer is handled in the acquire/release functions. Co-developed-by: John Ogness <john.ogness@linutronix.de> Signed-off-by: John Ogness <john.ogness@linutronix.de> Signed-off-by: Thomas Gleixner (Intel) <tglx@linutronix.de> Reviewed-by: Petr Mladek <pmladek@suse.com> Signed-off-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/20230916192007.608398-5-john.ogness@linutronix.de
* | printk: nbcon: Add acquire/release logicThomas Gleixner2023-09-181-0/+56
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Add per console acquire/release functionality. The state of the console is maintained in the "nbcon_state" atomic variable. The console is locked when: - The 'prio' field contains the priority of the context that owns the console. Only higher priority contexts are allowed to take over the lock. A value of 0 (NBCON_PRIO_NONE) means the console is not locked. - The 'cpu' field denotes on which CPU the console is locked. It is used to prevent busy waiting on the same CPU. Also it informs the lock owner that it has lost the lock in a more complex scenario when the lock was taken over by a higher priority context, released, and taken on another CPU with the same priority as the interrupted owner. The acquire mechanism uses a few more fields: - The 'req_prio' field is used by the handover approach to make the current owner aware that there is a context with a higher priority waiting for the friendly handover. - The 'unsafe' field allows to take over the console in a safe way in the middle of emitting a message. The field is set only when accessing some shared resources or when the console device is manipulated. It can be cleared, for example, after emitting one character when the console device is in a consistent state. - The 'unsafe_takeover' field is set when a hostile takeover took the console in an unsafe state. The console will stay in the unsafe state until re-initialized. The acquire mechanism uses three approaches: 1) Direct acquire when the console is not owned or is owned by a lower priority context and is in a safe state. 2) Friendly handover mechanism uses a request/grant handshake. It is used when the current owner has lower priority and the console is in an unsafe state. The requesting context: a) Sets its priority into the 'req_prio' field. b) Waits (with a timeout) for the owning context to unlock the console. c) Takes the lock and clears the 'req_prio' field. The owning context: a) Observes the 'req_prio' field set on exit from the unsafe console state. b) Gives up console ownership by clearing the 'prio' field. 3) Unsafe hostile takeover allows to take over the lock even when the console is an unsafe state. It is used only in panic() by the final attempt to flush consoles in a try and hope mode. Note that separate record buffers are used in panic(). As a result, the messages can be read and formatted without any risk even after using the hostile takeover in unsafe state. The release function simply clears the 'prio' field. All operations on @console::nbcon_state are atomic cmpxchg based to handle concurrency. The acquire/release functions implement only minimal policies: - Preference for higher priority contexts. - Protection of the panic CPU. All other policy decisions must be made at the call sites: - What is marked as an unsafe section. - Whether to spin-wait if there is already an owner and the console is in an unsafe state. - Whether to attempt an unsafe hostile takeover. The design allows to implement the well known: acquire() output_one_printk_record() release() The output of one printk record might be interrupted with a higher priority context. The new owner is supposed to reprint the entire interrupted record from scratch. Co-developed-by: John Ogness <john.ogness@linutronix.de> Signed-off-by: John Ogness <john.ogness@linutronix.de> Signed-off-by: Thomas Gleixner (Intel) <tglx@linutronix.de> Signed-off-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/20230916192007.608398-3-john.ogness@linutronix.de
* | printk: Add non-BKL (nbcon) console basic infrastructureThomas Gleixner2023-09-181-0/+31
|/ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The current console/printk subsystem is protected by a Big Kernel Lock, (aka console_lock) which has ill defined semantics and is more or less stateless. This puts severe limitations on the console subsystem and makes forced takeover and output in emergency and panic situations a fragile endeavour that is based on try and pray. The goal of non-BKL (nbcon) consoles is to break out of the console lock jail and to provide a new infrastructure that avoids the pitfalls and also allows console drivers to be gradually converted over. The proposed infrastructure aims for the following properties: - Per console locking instead of global locking - Per console state that allows to make informed decisions - Stateful handover and takeover As a first step, state is added to struct console. The per console state is an atomic_t using a 32bit bit field. Reserve state bits, which will be populated later in the series. Wire it up into the console register/unregister functionality. It was decided to use a bitfield because using a plain u32 with mask/shift operations resulted in uncomprehensible code. Co-developed-by: John Ogness <john.ogness@linutronix.de> Signed-off-by: John Ogness <john.ogness@linutronix.de> Signed-off-by: Thomas Gleixner (Intel) <tglx@linutronix.de> Reviewed-by: Petr Mladek <pmladek@suse.com> Signed-off-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/20230916192007.608398-2-john.ogness@linutronix.de
* printk: Add per-console suspended stateJohn Ogness2023-07-201-0/+3
| | | | | | | | | | | | | | | | | | | | | Currently the global @console_suspended is used to determine if consoles are in a suspended state. Its primary purpose is to allow usage of the console_lock when suspended without causing console printing. It is synchronized by the console_lock. Rather than relying on the console_lock to determine suspended state, make it an official per-console state that is set within console->flags. This allows the state to be queried via SRCU. Remove @console_suspended. Console printing will still be avoided when suspended because console_is_usable() returns false when the new suspended flag is set for that console. Signed-off-by: John Ogness <john.ogness@linutronix.de> Reviewed-by: Sergey Senozhatsky <senozhatsky@chromium.org> Reviewed-by: Petr Mladek <pmladek@suse.com> Signed-off-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/20230717194607.145135-7-john.ogness@linutronix.de
* Merge tag 'tty-6.3-rc1' of ↵Linus Torvalds2023-02-241-2/+3
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty Pull tty / serial driver updates from Greg KH: "Here is the big set of serial and tty driver updates for 6.3-rc1. Once again, Jiri and Ilpo have done a number of core vt and tty/serial layer cleanups that were much needed and appreciated. Other than that, it's just a bunch of little tty/serial driver updates: - qcom-geni-serial driver updates - liteuart driver updates - hvcs driver cleanups - n_gsm updates and additions for new features - more 8250 device support added - fpga/dfl update and additions - imx serial driver updates - fsl_lpuart updates - other tiny fixes and updates for serial drivers All of these have been in linux-next for a while with no reported problems" * tag 'tty-6.3-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty: (143 commits) tty: n_gsm: add keep alive support serial: imx: remove a redundant check dt-bindings: serial: snps-dw-apb-uart: add dma & dma-names properties soc: qcom: geni-se: Move qcom-geni-se.h to linux/soc/qcom/geni-se.h tty: n_gsm: add TIOCMIWAIT support tty: n_gsm: add RING/CD control support tty: n_gsm: mark unusable ioctl structure fields accordingly serial: imx: get rid of registers shadowing serial: imx: refine local variables in rxint() serial: imx: stop using USR2 in FIFO reading loop serial: imx: remove redundant USR2 read from FIFO reading loop serial: imx: do not break from FIFO reading loop prematurely serial: imx: do not sysrq broken chars serial: imx: work-around for hardware RX flood serial: imx: factor-out common code to imx_uart_soft_reset() serial: 8250_pci1xxxx: Add power management functions to quad-uart driver serial: 8250_pci1xxxx: Add RS485 support to quad-uart driver serial: 8250_pci1xxxx: Add driver for quad-uart support serial: 8250_pci: Add serial8250_pci_setup_port definition in 8250_pcilib.c tty: pcn_uart: fix memory leak with using debugfs_lookup() ...
| * VT: Add height parameter to con_font_get/set consw operationsSamuel Thibault2023-01-191-2/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The current con_font_get/set API currently hardcodes a 32-pixel-tall limitation, which only dates from the old VGA hardware which could not handle taller fonts than that. This change just adds a vpitch parameter to release this constraint. Drivers which do not support vpitch != 32 can just return EINVAL when it is not 32, font loading tools will revert to trying 32 and succeed. This change makes the fbcon driver consider vpitch appropriately, thus making it able to load large fonts. Signed-off-by: Samuel Thibault <samuel.thibault@ens-lyon.org> Link: https://lore.kernel.org/r/20230119151934.932642243@ens-lyon.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* | console: Document struct consoleThomas Gleixner2023-01-111-17/+37
| | | | | | | | | | | | | | | | | | | | Add kerneldoc comments to struct console. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: John Ogness <john.ogness@linutronix.de> Reviewed-by: Petr Mladek <pmladek@suse.com> Signed-off-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/20230109100800.1085541-4-john.ogness@linutronix.de
* | console: Use BIT() macros for @flags valuesThomas Gleixner2023-01-111-10/+36
|/ | | | | | | | | | | | Rather than manually calculating powers of 2, use the BIT() macros. Also take this opportunatity to cleanup and restructure the value comments into proper kerneldoc comments. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: John Ogness <john.ogness@linutronix.de> Reviewed-by: Petr Mladek <pmladek@suse.com> Signed-off-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/20230109100800.1085541-3-john.ogness@linutronix.de
* printk, xen: fbfront: create/use safe function for forcing preferredJohn Ogness2022-12-021-0/+1
| | | | | | | | | | | | | | | | | | With commit 9e124fe16ff2("xen: Enable console tty by default in domU if it's not a dummy") a hack was implemented to make sure that the tty console remains the console behind the /dev/console device. The main problem with the hack is that, after getting the console pointer to the tty console, it is assumed the pointer is still valid after releasing the console_sem. This assumption is incorrect and unsafe. Make the hack safe by introducing a new function console_force_preferred_locked() and perform the full operation under the console_list_lock. Signed-off-by: John Ogness <john.ogness@linutronix.de> Reviewed-by: Petr Mladek <pmladek@suse.com> Signed-off-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/20221116162152.193147-33-john.ogness@linutronix.de
* console: introduce console_is_registered()John Ogness2022-12-021-0/+28
| | | | | | | | | | | | | | | | | | Currently it is not possible for drivers to detect if they have already successfully registered their console. Several drivers have multiple paths that lead to console registration. To avoid attempting a 2nd registration (which leads to a WARN), drivers are implementing their own solution. Introduce console_is_registered() so drivers can easily identify if their console is currently registered. A _locked() variant is also provided if the caller is already holding the console_list_lock. Signed-off-by: John Ogness <john.ogness@linutronix.de> Reviewed-by: Petr Mladek <pmladek@suse.com> Signed-off-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/20221116162152.193147-22-john.ogness@linutronix.de
* console: introduce wrappers to read/write console flagsJohn Ogness2022-12-021-0/+45
| | | | | | | | | | | | | | | | | | After switching to SRCU for console list iteration, some readers will begin readings console->flags as a data race. Locklessly reading console->flags provides a consistent value because there is at most one CPU modifying console->flags and that CPU is using only read-modify-write operations. Introduce a wrapper for SRCU iterators to read console flags. Introduce a matching wrapper to write to flags of registered consoles. Writing to flags of registered consoles is synchronized by the console_list_lock. Signed-off-by: John Ogness <john.ogness@linutronix.de> Reviewed-by: Petr Mladek <pmladek@suse.com> Signed-off-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/20221116162152.193147-13-john.ogness@linutronix.de
* printk: introduce console_list_lockJohn Ogness2022-12-021-3/+20
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Currently there exist races in register_console(), where the types of registered consoles are checked (without holding the console_lock) and then after acquiring the console_lock, it is assumed that the list has not changed. Also, some code that performs console_unregister() make similar assumptions. It might be possible to fix these races using the console_lock. But it would require a complex analysis of all console drivers to make sure that the console_lock is not taken in match() and setup() callbacks. And we really prefer to split up and reduce the responsibilities of console_lock rather than expand its complexity. Therefore, introduce a new console_list_lock to provide full synchronization for any console list changes. In addition, also use console_list_lock for synchronization of console->flags updates. All flags are either static or modified only during the console registration. There are only two exceptions. The first exception is CON_ENABLED, which is also modified by console_start()/console_stop(). Therefore, these functions must also take the console_list_lock. The second exception is when the flags are modified by the console driver init code before the console is registered. These will be ignored because they are not visible to the rest of the system via the console_drivers list. Note that one of the various responsibilities of the console_lock is also intended to provide console list and console->flags synchronization. Later changes will update call sites relying on the console_lock for these purposes. Once all call sites have been updated, the console_lock will be relieved of synchronizing console_list and console->flags updates. Suggested-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: John Ogness <john.ogness@linutronix.de> Reviewed-by: Petr Mladek <pmladek@suse.com> Signed-off-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/87sficwokr.fsf@jogness.linutronix.de
* printk: Prepare for SRCU console list protectionJohn Ogness2022-12-021-1/+27
| | | | | | | | | | | | | | | | | | | Provide an NMI-safe SRCU protected variant to walk the console list. Note that all console fields are now set before adding the console to the list to avoid the console becoming visible by SCRU readers before being fully initialized. This is a preparatory change for a new console infrastructure which operates independent of the console BKL. Suggested-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: John Ogness <john.ogness@linutronix.de> Acked-by: Miguel Ojeda <ojeda@kernel.org> Reviewed-by: Paul E. McKenney <paulmck@kernel.org> Reviewed-by: Petr Mladek <pmladek@suse.com> Signed-off-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/20221116162152.193147-4-john.ogness@linutronix.de
* printk: Convert console_drivers list to hlistThomas Gleixner2022-12-021-3/+5
| | | | | | | | | | | | | | Replace the open coded single linked list with a hlist so a conversion to SRCU protected list walks can reuse the existing primitives. Co-developed-by: John Ogness <john.ogness@linutronix.de> Signed-off-by: John Ogness <john.ogness@linutronix.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Reviewed-by: Sergey Senozhatsky <senozhatsky@chromium.org> Reviewed-by: Petr Mladek <pmladek@suse.com> Signed-off-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/20221116162152.193147-3-john.ogness@linutronix.de
* Revert "printk: add kthread console printers"Petr Mladek2022-06-231-2/+0
| | | | | | | | | | | | | | | | | | | | | | This reverts commit 09c5ba0aa2fcfdadb17d045c3ee6f86d69270df7. This reverts commit b87f02307d3cfbda768520f0687c51ca77e14fc3. The testing of 5.19 release candidates revealed missing synchronization between early and regular console functionality. It would be possible to start the console kthreads later as a workaround. But it is clear that console lock serialized console drivers between each other. It opens a big area of possible problems that were not considered by people involved in the development and review. printk() is crucial for debugging kernel issues and console output is very important part of it. The number of consoles is huge and a proper review would take some time. As a result it need to be reverted for 5.19. Link: https://lore.kernel.org/r/YrBdjVwBOVgLfHyb@alley Signed-off-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/20220623145157.21938-6-pmladek@suse.com
* Revert "printk: extend console_lock for per-console locking"Petr Mladek2022-06-231-15/+0
| | | | | | | | | | | | | | | | | | | | This reverts commit 8e274732115f63c1d09136284431b3555bd5cc56. The testing of 5.19 release candidates revealed missing synchronization between early and regular console functionality. It would be possible to start the console kthreads later as a workaround. But it is clear that console lock serialized console drivers between each other. It opens a big area of possible problems that were not considered by people involved in the development and review. printk() is crucial for debugging kernel issues and console output is very important part of it. The number of consoles is huge and a proper review would take some time. As a result it need to be reverted for 5.19. Link: https://lore.kernel.org/r/YrBdjVwBOVgLfHyb@alley Signed-off-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/20220623145157.21938-5-pmladek@suse.com
* printk: extend console_lock for per-console lockingJohn Ogness2022-04-261-0/+15
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Currently threaded console printers synchronize against each other using console_lock(). However, different console drivers are unrelated and do not require any synchronization between each other. Removing the synchronization between the threaded console printers will allow each console to print at its own speed. But the threaded consoles printers do still need to synchronize against console_lock() callers. Introduce a per-console mutex and a new console boolean field @blocked to provide this synchronization. console_lock() is modified so that it must acquire the mutex of each console in order to set the @blocked field. Console printing threads will acquire their mutex while printing a record. If @blocked was set, the thread will go back to sleep instead of printing. The reason for the @blocked boolean field is so that console_lock() callers do not need to acquire multiple console mutexes simultaneously, which would introduce unnecessary complexity due to nested mutex locking. Also, a new field was chosen instead of adding a new @flags value so that the blocked status could be checked without concern of reading inconsistent values due to @flags updates from other contexts. Threaded console printers also need to synchronize against console_trylock() callers. Since console_trylock() may be called from any context, the per-console mutex cannot be used for this synchronization. (mutex_trylock() cannot be called from atomic contexts.) Introduce a global atomic counter to identify if any threaded printers are active. The threaded printers will also check the atomic counter to identify if the console has been locked by another task via console_trylock(). Note that @console_sem is still used to provide synchronization between console_lock() and console_trylock() callers. A locking overview for console_lock(), console_trylock(), and the threaded printers is as follows (pseudo code): console_lock() { down(&console_sem); for_each_console(con) { mutex_lock(&con->lock); con->blocked = true; mutex_unlock(&con->lock); } /* console_lock acquired */ } console_trylock() { if (down_trylock(&console_sem) == 0) { if (atomic_cmpxchg(&console_kthreads_active, 0, -1) == 0) { /* console_lock acquired */ } } } threaded_printer() { mutex_lock(&con->lock); if (!con->blocked) { /* console_lock() callers blocked */ if (atomic_inc_unless_negative(&console_kthreads_active)) { /* console_trylock() callers blocked */ con->write(); atomic_dec(&console_lock_count); } } mutex_unlock(&con->lock); } The console owner and waiter logic now only applies between contexts that have taken the console_lock via console_trylock(). Threaded printers never take the console_lock, so they do not have a console_lock to handover. Tasks that have used console_lock() will block the threaded printers using a mutex and if the console_lock is handed over to an atomic context, it would be unable to unblock the threaded printers. However, the console_trylock() case is really the only scenario that is interesting for handovers anyway. @panic_console_dropped must change to atomic_t since it is no longer protected exclusively by the console_lock. Since threaded printers remain asleep if they see that the console is locked, they now must be explicitly woken in __console_unlock(). This means wake_up_klogd() calls following a console_unlock() are no longer necessary and are removed. Also note that threaded printers no longer need to check @console_suspended. The check for the @blocked field implicitly covers the suspended console case. Signed-off-by: John Ogness <john.ogness@linutronix.de> Reviewed-by: Petr Mladek <pmladek@suse.com> Signed-off-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/878rrs6ft7.fsf@jogness.linutronix.de
* printk: add kthread console printersJohn Ogness2022-04-221-0/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Create a kthread for each console to perform console printing. During normal operation (@system_state == SYSTEM_RUNNING), the kthread printers are responsible for all printing on their respective consoles. During non-normal operation, console printing is done as it has been: within the context of the printk caller or within irqwork triggered by the printk caller, referred to as direct printing. Since threaded console printers are responsible for all printing during normal operation, this also includes messages generated via deferred printk calls. If direct printing is in effect during a deferred printk call, the queued irqwork will perform the direct printing. To make it clear that this is the only time that the irqwork will perform direct printing, rename the flag PRINTK_PENDING_OUTPUT to PRINTK_PENDING_DIRECT_OUTPUT. Threaded console printers synchronize against each other and against console lockers by taking the console lock for each message that is printed. Note that the kthread printers do not care about direct printing. They will always try to print if new records are available. They can be blocked by direct printing, but will be woken again once direct printing is finished. Console unregistration is a bit tricky because the associated kthread printer cannot be stopped while the console lock is held. A policy is implemented that states: whichever task clears con->thread (under the console lock) is responsible for stopping the kthread. unregister_console() will clear con->thread while the console lock is held and then stop the kthread after releasing the console lock. For consoles that have implemented the exit() callback, the kthread is stopped before exit() is called. Signed-off-by: John Ogness <john.ogness@linutronix.de> Reviewed-by: Petr Mladek <pmladek@suse.com> Signed-off-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/20220421212250.565456-14-john.ogness@linutronix.de
* printk: refactor and rework printing logicJohn Ogness2022-04-221-0/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Refactor/rework printing logic in order to prepare for moving to threaded console printing. - Move @console_seq into struct console so that the current "position" of each console can be tracked individually. - Move @console_dropped into struct console so that the current drop count of each console can be tracked individually. - Modify printing logic so that each console independently loads, prepares, and prints its next record. - Remove exclusive_console logic. Since console positions are handled independently, replaying past records occurs naturally. - Update the comments explaining why preemption is disabled while printing from printk() context. With these changes, there is a change in behavior: the console replaying the log (formerly exclusive console) will no longer block other consoles. New messages appear on the other consoles while the newly added console is still replaying. Signed-off-by: John Ogness <john.ogness@linutronix.de> Reviewed-by: Petr Mladek <pmladek@suse.com> Signed-off-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/20220421212250.565456-10-john.ogness@linutronix.de
* drm: Move nomodeset kernel parameter to the DRM subsystemJavier Martinez Canillas2021-11-271-6/+0
| | | | | | | | | | | | | | | | | | | | | The "nomodeset" kernel cmdline parameter is handled by the vgacon driver but the exported vgacon_text_force() symbol is only used by DRM drivers. It makes much more sense for the parameter logic to be in the subsystem of the drivers that are making use of it. Let's move the vgacon_text_force() function and related logic to the DRM subsystem. While doing that, rename it to drm_firmware_drivers_only() and make it return true if "nomodeset" was used and false otherwise. This is a better description of the condition that the drivers are testing for. Suggested-by: Daniel Vetter <daniel.vetter@ffwll.ch> Signed-off-by: Javier Martinez Canillas <javierm@redhat.com> Acked-by: Thomas Zimmermann <tzimmermann@suse.de> Acked-by: Jani Nikula <jani.nikula@intel.com> Acked-by: Pekka Paalanen <pekka.paalanen@collabora.com> Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Link: https://patchwork.freedesktop.org/patch/msgid/20211112133230.1595307-4-javierm@redhat.com
* serial: core: Fix initializing and restoring termios speedPali Rohár2021-10-051-0/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Since commit edc6afc54968 ("tty: switch to ktermios and new framework") termios speed is no longer stored only in c_cflag member but also in new additional c_ispeed and c_ospeed members. If BOTHER flag is set in c_cflag then termios speed is stored only in these new members. Therefore to correctly restore termios speed it is required to store also ispeed and ospeed members, not only cflag member. In case only cflag member with BOTHER flag is restored then functions tty_termios_baud_rate() and tty_termios_input_baud_rate() returns baudrate stored in c_ospeed / c_ispeed member, which is zero as it was not restored too. If reported baudrate is invalid (e.g. zero) then serial core functions report fallback baudrate value 9600. So it means that in this case original baudrate is lost and kernel changes it to value 9600. Simple reproducer of this issue is to boot kernel with following command line argument: "console=ttyXXX,86400" (where ttyXXX is the device name). For speed 86400 there is no Bnnn constant and therefore kernel has to represent this speed via BOTHER c_cflag. Which means that speed is stored only in c_ospeed and c_ispeed members, not in c_cflag anymore. If bootloader correctly configures serial device to speed 86400 then kernel prints boot log to early console at speed speed 86400 without any issue. But after kernel starts initializing real console device ttyXXX then speed is changed to fallback value 9600 because information about speed was lost. This patch fixes above issue by storing and restoring also ispeed and ospeed members, which are required for BOTHER flag. Fixes: edc6afc54968 ("[PATCH] tty: switch to ktermios and new framework") Cc: stable@vger.kernel.org Signed-off-by: Pali Rohár <pali@kernel.org> Link: https://lore.kernel.org/r/20211002130900.9518-1-pali@kernel.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* Revert "init/console: Use ttynull as a fallback when there is no console"Petr Mladek2021-01-081-3/+0
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This reverts commit 757055ae8dedf5333af17b3b5b4b70ba9bc9da4e. The commit caused that ttynull was used as the default console on several systems[1][2][3]. As a result, the console was blank even when a better alternative existed. It happened when there was no console configured on the command line and ttynull_init() was the first initcall calling register_console(). Or it happened when /dev/ did not exist when console_on_rootfs() was called. It was not able to open /dev/console even though a console driver was registered. It tried to add ttynull console but it obviously did not help. But ttynull became the preferred console and was used by /dev/console when it was available later. The commit tried to fix a historical problem that have been there for ages. The primary motivation was the commit 3cffa06aeef7ece30f6 ("printk/console: Allow to disable console output by using console="" or console=null"). It provided a clean solution for a workaround that was widely used and worked only by chance. This revert causes that the console="" or console=null command line options will again work only by chance. These options will cause that a particular console will be preferred and the default (tty) ones will not get enabled. There will be no console registered at all. As a result there won't be stdin, stdout, and stderr for the init process. But it worked exactly this way even before. The proper solution has to fulfill many conditions: + Register ttynull only when explicitly required or as the ultimate fallback. + ttynull should get associated with /dev/console but it must not become preferred console when used as a fallback. Especially, it must still be possible to replace it by a better console later. Such a change requires clean up of the register_console() code. Otherwise, it would be even harder to follow. Especially, the use of has_preferred_console and CON_CONSDEV flag is tricky. The clean up is risky. The ordering of consoles is not well defined. And any changes tend to break existing user settings. Do the revert at the least risky solution for now. [1] https://lore.kernel.org/linux-kselftest/20201221144302.GR4077@smile.fi.intel.com/ [2] https://lore.kernel.org/lkml/d2a3b3c0-e548-7dd1-730f-59bc5c04e191@synopsys.com/ [3] https://patchwork.ozlabs.org/project/linux-um/patch/20210105120128.10854-1-thomas@m3y3r.de/ Reported-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Reported-by: Vineet Gupta <vgupta@synopsys.com> Reported-by: Thomas Meyer <thomas@m3y3r.de> Signed-off-by: Petr Mladek <pmladek@suse.com> Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Acked-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Merge tag 'printk-for-5.11' of ↵Linus Torvalds2020-12-161-0/+3
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux Pull printk updates from Petr Mladek: - Finally allow parallel writes and reads into/from the lockless ringbuffer. But it is not a complete solution. Readers are still serialized against each other. And nested writes are still prevented by printk_safe per-CPU buffers. - Use ttynull as the ultimate fallback for /dev/console. - Officially allow disabling console output by using console="" or console=null - A few code cleanups * tag 'printk-for-5.11' of git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux: printk: remove logbuf_lock writer-protection of ringbuffer printk: inline log_output(),log_store() in vprintk_store() printk: remove obsolete dead assignment printk/console: Allow to disable console output by using console="" or console=null init/console: Use ttynull as a fallback when there is no console printk: ringbuffer: Reference text_data_ring directly in callees.
generated by cgit v1.2.3 (git 2.25.1) at 2024-10-08 23:02:08 +0000