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* | tty: Use 'disc' for line discipline index namePeter Hurley2016-01-271-1/+1
| | | | | | | | | | | | | | | | | | | | tty->ldisc is a ptr to struct tty_ldisc, but unfortunately 'ldisc' is also used as a parameter or local name to refer to the line discipline index value (ie, N_TTY, N_GSM, etc.); instead prefer the name used by the line discipline registration/ref counting functions. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* | tty: Remove __lockfunc annotation from tty lock functionsPeter Hurley2016-01-271-4/+4
| | | | | | | | | | | | | | | | The tty lock/unlock code does not belong in the special lockfunc section which is treated specially by stack backtraces. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* | tty: Re-declare tty_driver_remove_tty() file scopePeter Hurley2016-01-271-2/+0
| | | | | | | | | | | | | | tty_driver_remove_tty() is only local-scope; declare as static. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* | tty: Fix tty_init_termios() declarationPeter Hurley2016-01-271-3/+1
| | | | | | | | | | | | | | | | | | | | | | tty_init_termios() never returns an error; re-declare as void. Remove unnecessary error handling from callers. Remove extern declarations of tty_free_termios() and free_tty_struct() and re-declare in file scope. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Acked-by: Johan Hovold <johan@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* | tty: Fix ldisc leak in failed tty_init_dev()Peter Hurley2016-01-271-1/+0
|/ | | | | | | | | | | | | | | release_tty() leaks the ldisc instance when called directly (rather than when releasing the file descriptor from tty_release()). Since tty_ldisc_release() clears tty->ldisc, releasing the ldisc instance at tty teardown if tty->ldisc is non-null is not in danger of double-releasing the ldisc. Remove deinitialize_tty_struct() now that free_tty_struct() always performs the tty_ldisc_deinit(). Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: Wait interruptibly for tty lock on reopenPeter Hurley2016-01-261-0/+1
| | | | | | | | | | Allow a signal to interrupt the wait for a tty reopen; eg., if the tty has starting final close and is waiting for the device to drain. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Cc: stable <stable@vger.kernel.org> # 4.4 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: Remove dead tty_write_flush() declaration and macroPeter Hurley2015-12-131-4/+0
| | | | | | | | tty_write_flush() has no definition and the TTY_WRITE_FLUSH() macro is never invoked; remove. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: Remove __func__ from tty_debug() macroPeter Hurley2015-12-131-2/+1
| | | | | | | | | | | | | Now that tty_debug() macro uses pr_debug(), the function name can be printed when using dynamic debug; printing the function name within the format string is redundant. Remove the __func__ parameter and print specifier from the format string. Add context to messages for when the function name is not printed by dynamic debug, or when dynamic debug is not enabled. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: Define tty_*() printk macrosPeter Hurley2015-12-131-1/+11
| | | | | | | | | | | | | Since not all ttys are devices (eg., SysV ptys), dev_*() printk macros cannot be used. Define tty_*() printk macros that output in similar format to dev_*() macros (ie., <driver> <tty>: .....). Transform the most-trivial printk( LEVEL ...) usage to tty_*() usage. NB: The function name has been eliminated from messages with unique context, or prefixed to the format when given. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: core: Add helper fn to deref tty driver namePeter Hurley2015-12-131-0/+1
| | | | | | | | Similar to tty_name(), add tty_driver_name() helper to safely dereference tty->driver->name (otherwise return empty string). Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: Make tty_paranoia_check() file scopePeter Hurley2015-12-131-2/+0
| | | | | | | | tty_paranoia_check() is only used within drivers/tty/tty_io.c; remove extern declaration in header and limit symbol to file scope. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: Improve tty_debug() macroPeter Hurley2015-12-131-5/+2
| | | | | | | | | | | | Incorporate suggestions for tty core debug macro improvements - printk(KERN_DEBUG) => pr_debug() - ##args => ##__VA_ARGS__ - remove do {} while() - output tty_name() first cc: Joe Perches <joe@perches.com> Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: audit: Fix audit sourcePeter Hurley2015-11-201-3/+3
| | | | | | | | | | | | The data to audit/record is in the 'from' buffer (ie., the input read buffer). Fixes: 72586c6061ab ("n_tty: Fix auditing support for cannonical mode") Cc: stable <stable@vger.kernel.org> # 4.1+ Cc: Miloslav Trmač <mitr@redhat.com> Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Acked-by: Laura Abbott <labbott@fedoraproject.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: Abstract tty buffer workPeter Hurley2015-10-171-0/+2
| | | | | | | | Introduce API functions to restart and cancel tty buffer work, rather than manipulate buffer work directly. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: Combine SIGTTOU/SIGTTIN handlingPeter Hurley2015-10-171-0/+1
| | | | | | | | | | | | | | The job_control() check in n_tty_read() has nearly identical purpose and results as tty_check_change(). Both functions' purpose is to determine if the current task's pgrp is the foreground pgrp for the tty, and if not, to signal the current pgrp. Introduce __tty_check_change() which takes the signal to send and performs the shared operations for job control() and tty_check_change(). Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: Remove wait_event_interruptible_tty()Peter Hurley2015-10-171-26/+0
| | | | | | | | In-tree users of wait_event_interruptible_tty() have been removed; remove. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: Remove tty_port::close_waitPeter Hurley2015-10-171-1/+0
| | | | | | | | | | | | With the removal of tty_wait_until_sent_from_close(), tty drivers no longer wait during open for parallel closes to complete (instead, the tty core waits before calling the driver open() method). Thus, the close_wait waitqueue is no longer used for waiting. Remove struct tty_port::close_wait. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: Remove tty_wait_until_sent_from_close()Peter Hurley2015-10-171-18/+0
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | tty_wait_until_sent_from_close() drops the tty lock while waiting for the tty driver to finish sending previously accepted data (ie., data remaining in its write buffer and transmit fifo). tty_wait_until_sent_from_close() was added by commit a57a7bf3fc7e ("TTY: define tty_wait_until_sent_from_close") to prevent the entire tty subsystem from being unable to open new ttys while waiting for one tty to close while output drained. However, since commit 0911261d4cb6 ("tty: Don't take tty_mutex for tty count changes"), holding a tty lock while closing does not prevent other ttys from being opened/closed/hung up, but only prevents lifetime event changes for the tty under lock. Holding the tty lock while waiting for output to drain does prevent parallel non-blocking opens (O_NONBLOCK) from advancing or returning while the tty lock is held. However, all parallel opens _already_ block even if the tty lock is dropped while closing and the parallel open advances. Blocking in open has been in mainline since at least 2.6.29 (see tty_port_block_til_ready(); note the test for O_NONBLOCK is _after_ the wait while ASYNC_CLOSING). IOW, before this patch a non-blocking open will sleep anyway for the _entire_ duration of a parallel hardware shutdown, and when it wakes, the error return will cause a release of its tty, and it will restart with a fresh attempt to open. Similarly with a blocking open that is already waiting; when it's woken, the hardware shutdown has already completed to ASYNC_INITIALIZED is not set, which forces a release and restart as well. So, holding the tty lock across the _entire_ close (which is what this patch does), even while waiting for output to drain, is equivalent to the current outcome wrt parallel opens. Cc: Alan Cox <alan@linux.intel.com> Cc: David Laight <David.Laight@aculab.com> CC: Arnd Bergmann <arnd@arndb.de> CC: Karsten Keil <isdn@linux-pingi.de> CC: linuxppc-dev@lists.ozlabs.org Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: core: Add tty_debug() for printk(KERN_DEBUG) messagesPeter Hurley2015-07-231-0/+6
| | | | | | | | | | | Introduce tty_debug() macro to output uniform debug information for tty core debug messages (function name and tty name). Note: printk(KERN_DEBUG) is retained here over pr_debug() since messages can be enabled in non-DEBUG builds. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* Merge 4.1-rc4 into tty-nextGreg Kroah-Hartman2015-05-181-1/+1
|\ | | | | | | | | | | This resolves some tty driver merge issues. Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| * pty: Fix input race when closingPeter Hurley2015-05-101-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | A read() from a pty master may mistakenly indicate EOF (errno == -EIO) after the pty slave has closed, even though input data remains to be read. For example, pty slave | input worker | pty master | | | | n_tty_read() pty_write() | | input avail? no add data | | sleep schedule worker --->| | . |---> flush_to_ldisc() | . pty_close() | fill read buffer | . wait for worker | wakeup reader --->| . | read buffer full? |---> input avail ? yes |<--- yes - exit worker | copy 4096 bytes to user TTY_OTHER_CLOSED <---| |<--- kick worker | | **** New read() before worker starts **** | | n_tty_read() | | input avail? no | | TTY_OTHER_CLOSED? yes | | return -EIO Several conditions are required to trigger this race: 1. the ldisc read buffer must become full so the input worker exits 2. the read() count parameter must be >= 4096 so the ldisc read buffer is empty 3. the subsequent read() occurs before the kicked worker has processed more input However, the underlying cause of the race is that data is pipelined, while tty state is not; ie., data already written by the pty slave end is not yet visible to the pty master end, but state changes by the pty slave end are visible to the pty master end immediately. Pipeline the TTY_OTHER_CLOSED state through input worker to the reader. 1. Introduce TTY_OTHER_DONE which is set by the input worker when TTY_OTHER_CLOSED is set and either the input buffers are flushed or input processing has completed. Readers/polls are woken when TTY_OTHER_DONE is set. 2. Reader/poll checks TTY_OTHER_DONE instead of TTY_OTHER_CLOSED. 3. A new input worker is started from pty_close() after setting TTY_OTHER_CLOSED, which ensures the TTY_OTHER_DONE state will be set if the last input worker is already finished (or just about to exit). Remove tty_flush_to_ldisc(); no in-tree callers. Fixes: 52bce7f8d4fc ("pty, n_tty: Simplify input processing on final close") Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=96311 BugLink: http://bugs.launchpad.net/bugs/1429756 Cc: <stable@vger.kernel.org> # 3.19+ Reported-by: Andy Whitcroft <apw@canonical.com> Reported-by: H.J. Lu <hjl.tools@gmail.com> Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* | tty: remove buf parameter from tty_name()Rasmus Villemoes2015-05-061-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | tty_name no longer uses the buf parameter, so remove it along with all the 64 byte stack buffers that used to be passed in. Mostly generated by the coccinelle script @depends on patch@ identifier buf; constant C; expression tty; @@ - char buf[C]; <+... - tty_name(tty, buf) + tty_name(tty) ...+> allmodconfig compiles, so I'm fairly confident the stack buffers weren't used for other purposes as well. Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk> Reviewed-by: Peter Hurley <peter@hurleysoftware.com> Acked-by: Jesper Nilsson <jesper.nilsson@axis.com> Acked-by: Dmitry Torokhov <dmitry.torokhov@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* | tty: constify return type of tty_nameRasmus Villemoes2015-05-061-1/+1
|/ | | | | | | | | | | | | | All users of tty_name pass the result directly to a printf-like function. This means we can actually let tty_name return the literal "NULL tty" or tty->name directly, avoiding the strcpy and a lot of medium-sized stack buffers. In preparation for that, make the return type const char*. While at it, we can also constify the tty parameter. Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk> Reviewed-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: Re-add external interface for tty_set_termios()Frederic Danis2015-04-281-0/+1
| | | | | | | | | | This is needed by Bluetooth hci_uart module to be able to change speed of Bluetooth controller and local UART. Signed-off-by: Frederic Danis <frederic.danis@linux.intel.com> Reviewed-by: Peter Hurley <peter@hurleysoftware.com> Cc: Marcel Holtmann <marcel@holtmann.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: Remove external interface for tty_set_termios()Peter Hurley2015-02-021-1/+0
| | | | | | | | | | | | | | | tty_set_termios() is an internal helper intended for file scope use. UART drivers which are capable of driving the RTS pin must properly handle the tiocmset() method, regardless of termios settings. A failure to do so is a UART driver bug and should be fixed there. Do not use this interface to workaround UART driver bugs. Cc: Johan Hedberg <johan.hedberg@gmail.com> Cc: <linux-bluetooth@vger.kernel.org> Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Acked-by: Marcel Holtmann <marcel@holtmann.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* n_tty: Fix signal handling flushesPeter Hurley2015-02-021-0/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | BRKINT and ISIG requires input and output flush when a signal char is received. However, the order of operations is significant since parallel i/o may be ongoing. Merge the signal handling for BRKINT with ISIG handling. Process the signal first. This ensures any ongoing i/o is aborted; without this, a waiting writer may continue writing after the flush occurs and after the signal char has been echoed. Write lock the termios_rwsem, which excludes parallel writers from pushing new i/o until after the output buffers are flushed; claiming the write lock is necessary anyway to exclude parallel readers while the read buffer is flushed. Subclass the termios_rwsem for ptys since the slave pty performing the flush may appear to reorder the termios_rwsem->tty buffer lock lock order; adding annotation clarifies that slave tty_buffer lock-> slave termios_rwsem -> master tty_buffer lock is a valid lock order. Flush the echo buffer. In this context, the echo buffer is 'output'. Otherwise, the output will appear discontinuous because the output buffer was cleared which contains older output than the echo buffer. Open-code the read buffer flush since the input worker does not need kicking (this is the input worker). Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* pty: Fix buffer flush deadlockPeter Hurley2015-02-021-0/+4
| | | | | | | | | | | | | | | | | The pty driver does not clear its write buffer when commanded. This is to avoid an apparent deadlock between parallel flushes from both pty ends; specifically when handling either BRK or INTR input. However, parallel flushes from this source is not possible since the pty master can never be set to BRKINT or ISIG. Parallel flushes from other sources are possible but these do not threaten deadlocks. Annotate the tty buffer mutex for lockdep to represent the nested tty_buffer locking which occurs when the pty slave is processing input (its buffer mutex held) and receives INTR or BRK and acquires the linked tty buffer mutex via tty_buffer_flush(). Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: Make lock subclasses available for other tty locksPeter Hurley2015-02-021-0/+17
| | | | | | | | | | | Besides nested legacy_mutex locking which is required on pty pair teardown, other nested pty operations require lock subclassing. Move lock subclass definition to tty interface header, include/linux/tty.h, and document its use. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: Convert tty->closing to intPeter Hurley2014-11-061-1/+1
| | | | | | | | tty->closing is a bitfield member; prevent corruption from non-atomic update by assigning a unique memory location. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: Remove defunct serial_console_init() declarationPeter Hurley2014-11-051-4/+0
| | | | | | | | | | | | serial_console_init() is not defined by the tty core; remove declaration. Note that the powerpc arch boot code contains a serial_console_init() declaration in arch/powerpc/boot/ops.h which is restricted to the powerpc arch boot. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: Remove defunct pcxe_open() declarationPeter Hurley2014-11-051-4/+0
| | | | | | | pcxe_open() has no definition in mainline; remove declaration. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: Flush ldisc buffer atomically with tty flip buffersPeter Hurley2014-11-051-1/+1
| | | | | | | | | | | | | | | | | | | | | tty_ldisc_flush() first clears the line discipline input buffer, then clears the tty flip buffers. However, this allows for existing data in the tty flip buffers to be added after the ldisc input buffer has been cleared, but before the flip buffers have been cleared. Add an optional ldisc parameter to tty_buffer_flush() to allow tty_ldisc_flush() to pass the ldisc to clear. NB: Initially, the plan was to do this automatically in tty_buffer_flush(). However, an audit of the behavior of existing line disciplines showed that performing a ldisc buffer flush on ioctl(TCFLSH) was not always the outcome. For example, some line disciplines have flush_buffer() methods but not ioctl() methods, so a ->flush_buffer() command would be unexpected. Reviewed-by: Alan Cox <alan@linux.intel.com> Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: Remove tty_unhangup() declarationPeter Hurley2014-11-051-1/+0
| | | | | | | | The tty_unhangup() function is not defined. Reviewed-by: Alan Cox <alan@linux.intel.com> Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: Preset lock subclass for nested tty locksPeter Hurley2014-11-051-0/+1
| | | | | | | | | Eliminate the requirement of specifying the tty lock nesting at lock time; instead, set the lock subclass for slave ptys at pty install (normal ttys and master ptys use subclass 0). Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: Change tty lock order to master->slavePeter Hurley2014-11-051-5/+2
| | | | | | | | | | | | | | | | | | | When releasing the master pty, the slave pty also needs to be locked to prevent concurrent tty count changes for the slave pty and to ensure that only one parallel master and slave release observe the final close, and proceed to destruct the pty pair. Conversely, when releasing the slave pty, locking the master pty is not necessary (since the master's state can be inferred by the slave tty count). Introduce tty_lock_slave()/tty_unlock_slave() which acquires/releases the tty lock of the slave pty. Remove tty_lock_pair()/tty_unlock_pair(). Dropping the tty_lock is no longer required to re-establish a stable lock order. Reviewed-by: Alan Cox <alan@linux.intel.com> Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: Simplify tty_ldisc_release() interfacePeter Hurley2014-11-051-1/+1
| | | | | | | | | Passing the 'other' tty to tty_ldisc_release() only makes sense for a pty pair; make o_tty function local instead. Reviewed-by: Alan Cox <alan@linux.intel.com> Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: Remove TTY_CLOSINGPeter Hurley2014-11-051-1/+0
| | | | | | | | | | Now that re-open is not permitted for a legacy BSD pty master, using TTY_CLOSING to indicate when a tty can be torn-down is no longer necessary. Reviewed-by: Alan Cox <alan@linux.intel.com> Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: Remove TTY_HUPPINGPeter Hurley2014-11-051-1/+0
| | | | | | | | | | | | Now that tty_ldisc_hangup() does not drop the tty lock, it is no longer possible to observe TTY_HUPPING while holding the tty lock on another cpu. Remove TTY_HUPPING bit definition. Reviewed-by: Alan Cox <alan@linux.intel.com> Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: Remove tty_pair_get_tty()/tty_pair_get_pty() apiPeter Hurley2014-11-051-3/+0
| | | | | | | | | | tty_pair_get_pty() has no in-tree users and tty_pair_get_tty() has only one file-local user. Remove the external declarations, the export declarations, and declare tty_pair_get_tty() static. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Reviewed-by: Alan Cox <alan@linux.intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: Fix width of unsigned long bitfield paddingPeter Hurley2014-09-251-2/+2
| | | | | | | | | | | | | | | | Commit c545b66c6922b002b5fe224a6eaec58c913650b5, 'tty: Serialize tcflow() with other tty flow control changes' and commit 99416322dd16b810ba74098cc50ef2a844091d35, 'tty: Workaround Alpha non-atomic byte storage in tty_struct' work around compiler bugs and non-atomic storage on multiple arches by padding bitfields out to the declared type which is unsigned long. However, the width varies by arch. Pad bitfields to actual width of unsigned long (which is BITS_PER_LONG). Reported-by: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: Workaround Alpha non-atomic byte storage in tty_structPeter Hurley2014-09-231-2/+3
| | | | | | | | | | | | | | | | | | | | | | | | | The Alpha EV4/EV5 cpus can corrupt adjacent byte and short data because those cpus use RMW to store byte and short data. Thus, concurrent adjacent byte stores could become corrupted, if serialized by a different lock. tty_struct uses different locks to protect certain fields within the structure, and thus is vulnerable to byte stores which are not atomic. Merge the ->ctrl_status byte and packet mode bit, both protected by the ->ctrl_lock, into an unsigned long. The padding bits are necessary to force the compiler to allocate the type specified; otherwise, gcc will ignore the type specifier and allocate the minimum number of bytes required to store the bitfield. In turn, this would allow Alpha EV4/EV5 cpus to corrupt adjacent byte or short storage (because those cpus use RMW to store byte and short data). gcc versions < 4.7.2 will also corrupt storage adjacent to bitfields smaller than unsigned long on ia64, ppc64, hppa64, and sparc64, thus requiring more than unsigned int storage (which would otherwise be sufficient to fix the Alpha non-atomic storage problem). Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: Move and rename send_prio_char() as tty_send_xchar()Peter Hurley2014-09-231-2/+1
| | | | | | | | | Relocate the file-scope function, send_prio_char(), as a global helper tty_send_xchar(). Remove the global declarations for tty_write_lock()/tty_write_unlock(), as these are file-scope only now. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: Serialize tcflow() with other tty flow control changesPeter Hurley2014-09-231-2/+3
| | | | | | | | | | | | | | | | | | | | | | | Use newly-introduced tty->flow_lock to serialize updates to tty->flow_stopped (via tcflow()) and with concurrent tty flow control changes from other sources. Merge the storage for ->stopped and ->flow_stopped, now that both flags are serialized by ->flow_lock. The padding bits are necessary to force the compiler to allocate the type specified; otherwise, gcc will ignore the type specifier and allocate the minimum number of bytes necessary to store the bitfield. In turn, this would allow Alpha EV4 and EV5 cpus to corrupt adjacent byte storage because those cpus use RMW to store byte and short data. gcc versions < 4.7.2 will also corrupt storage adjacent to bitfields smaller than unsigned long on ia64, ppc64, hppa64 and sparc64, thus requiring more than unsigned int storage (which would otherwise be sufficient to workaround the Alpha non-atomic byte/short storage problem). Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: Serialize tty flow control changes with flow_lockPeter Hurley2014-09-231-1/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | Without serialization, the flow control state can become inverted wrt. the actual hardware state. For example, CPU 0 | CPU 1 stop_tty() | lock ctrl_lock | tty->stopped = 1 | unlock ctrl_lock | | start_tty() | lock ctrl_lock | tty->stopped = 0 | unlock ctrl_lock | driver->start() driver->stop() | In this case, the flow control state now indicates the tty has been started, but the actual hardware state has actually been stopped. Introduce tty->flow_lock spinlock to serialize tty flow control changes. Split out unlocked __start_tty()/__stop_tty() flavors for use by ioctl(TCXONC) in follow-on patch. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: Convert tty_struct bitfield to intsPeter Hurley2014-09-231-1/+4
| | | | | | | | | | | | | | | | | | | | The stopped, hw_stopped, flow_stopped and packet bits are smp-unsafe and interrupt-unsafe. For example, CPU 0 | CPU 1 | tty->flow_stopped = 1 | tty->hw_stopped = 0 One of these updates will be corrupted, as the bitwise operation on the bitfield is non-atomic. Ensure each flag has a separate memory location, so concurrent updates do not corrupt orthogonal states. Because DEC Alpha EV4 and EV5 cpus (from 1995) perform RMW on smaller-than-machine-word storage, "separate memory location" must be int instead of byte. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* drivers: tty: Merge alloc_tty_struct and initialize_tty_structRasmus Villemoes2014-07-111-3/+1
| | | | | | | | | The two functions alloc_tty_struct and initialize_tty_struct are always called together. Merge them into alloc_tty_struct, updating its prototype and the only two callers of these functions. Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* Revert "tty: Fix race condition between __tty_buffer_request_room and ↵Peter Hurley2014-05-031-1/+0
| | | | | | | | | | | | | | | | flush_to_ldisc" This reverts commit 6a20dbd6caa2358716136144bf524331d70b1e03. Although the commit correctly identifies an unsafe race condition between __tty_buffer_request_room() and flush_to_ldisc(), the commit fixes the race with an unnecessary spinlock in a lockless algorithm. The follow-on commit, "tty: Fix lockless tty buffer race" fixes the race locklessly. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: Fix race condition between __tty_buffer_request_room and flush_to_ldiscManfred Schlaegl2014-04-241-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The race was introduced while development of linux-3.11 by e8437d7ecbc50198705331449367d401ebb3181f and e9975fdec0138f1b2a85b9624e41660abd9865d4. Originally it was found and reproduced on linux-3.12.15 and linux-3.12.15-rt25, by sending 500 byte blocks with 115kbaud to the target uart in a loop with 100 milliseconds delay. In short: 1. The consumer flush_to_ldisc is on to remove the head tty_buffer. 2. The producer adds a number of bytes, so that a new tty_buffer must be allocated and added by __tty_buffer_request_room. 3. The consumer removes the head tty_buffer element, without handling newly committed data. Detailed example: * Initial buffer: * Head, Tail -> 0: used=250; commit=250; read=240; next=NULL * Consumer: ''flush_to_ldisc'' * consumed 10 Byte * buffer: * Head, Tail -> 0: used=250; commit=250; read=250; next=NULL {{{ count = head->commit - head->read; // count = 0 if (!count) { // enter // INTERRUPTED BY PRODUCER -> if (head->next == NULL) break; buf->head = head->next; tty_buffer_free(port, head); continue; } }}} * Producer: tty_insert_flip_... 10 bytes + tty_flip_buffer_push * buffer: * Head, Tail -> 0: used=250; commit=250; read=250; next=NULL * added 6 bytes: head-element filled to maximum. * buffer: * Head, Tail -> 0: used=256; commit=250; read=250; next=NULL * added 4 bytes: __tty_buffer_request_room is called * buffer: * Head -> 0: used=256; commit=256; read=250; next=1 * Tail -> 1: used=4; commit=0; read=250 next=NULL * push (tty_flip_buffer_push) * buffer: * Head -> 0: used=256; commit=256; read=250; next=1 * Tail -> 1: used=4; commit=4; read=250 next=NULL * Consumer {{{ count = head->commit - head->read; if (!count) { // INTERRUPTED BY PRODUCER <- if (head->next == NULL) // -> no break break; buf->head = head->next; tty_buffer_free(port, head); // ERROR: tty_buffer head freed -> 6 bytes lost continue; } }}} This patch reintroduces a spin_lock to protect this case. Perhaps later a lock-less solution could be found. Signed-off-by: Manfred Schlaegl <manfred.schlaegl@gmx.at> Cc: stable <stable@vger.kernel.org> # 3.11 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-nextLinus Torvalds2014-04-021-3/+3
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Pull networking updates from David Miller: "Here is my initial pull request for the networking subsystem during this merge window: 1) Support for ESN in AH (RFC 4302) from Fan Du. 2) Add full kernel doc for ethtool command structures, from Ben Hutchings. 3) Add BCM7xxx PHY driver, from Florian Fainelli. 4) Export computed TCP rate information in netlink socket dumps, from Eric Dumazet. 5) Allow IPSEC SA to be dumped partially using a filter, from Nicolas Dichtel. 6) Convert many drivers to pci_enable_msix_range(), from Alexander Gordeev. 7) Record SKB timestamps more efficiently, from Eric Dumazet. 8) Switch to microsecond resolution for TCP round trip times, also from Eric Dumazet. 9) Clean up and fix 6lowpan fragmentation handling by making use of the existing inet_frag api for it's implementation. 10) Add TX grant mapping to xen-netback driver, from Zoltan Kiss. 11) Auto size SKB lengths when composing netlink messages based upon past message sizes used, from Eric Dumazet. 12) qdisc dumps can take a long time, add a cond_resched(), From Eric Dumazet. 13) Sanitize netpoll core and drivers wrt. SKB handling semantics. Get rid of never-used-in-tree netpoll RX handling. From Eric W Biederman. 14) Support inter-address-family and namespace changing in VTI tunnel driver(s). From Steffen Klassert. 15) Add Altera TSE driver, from Vince Bridgers. 16) Optimizing csum_replace2() so that it doesn't adjust the checksum by checksumming the entire header, from Eric Dumazet. 17) Expand BPF internal implementation for faster interpreting, more direct translations into JIT'd code, and much cleaner uses of BPF filtering in non-socket ocntexts. From Daniel Borkmann and Alexei Starovoitov" * git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next: (1976 commits) netpoll: Use skb_irq_freeable to make zap_completion_queue safe. net: Add a test to see if a skb is freeable in irq context qlcnic: Fix build failure due to undefined reference to `vxlan_get_rx_port' net: ptp: move PTP classifier in its own file net: sxgbe: make "core_ops" static net: sxgbe: fix logical vs bitwise operation net: sxgbe: sxgbe_mdio_register() frees the bus Call efx_set_channels() before efx->type->dimension_resources() xen-netback: disable rogue vif in kthread context net/mlx4: Set proper build dependancy with vxlan be2net: fix build dependency on VxLAN mac802154: make csma/cca parameters per-wpan mac802154: allow only one WPAN to be up at any given time net: filter: minor: fix kdoc in __sk_run_filter netlink: don't compare the nul-termination in nla_strcmp can: c_can: Avoid led toggling for every packet. can: c_can: Simplify TX interrupt cleanup can: c_can: Store dlc private can: c_can: Reduce register access can: c_can: Make the code readable ...
| * tty: Fix ref counting for port krefsPeter Hurley2014-02-141-3/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The tty core supports two models for handling tty_port lifetimes; the tty_port can use the kref supplied by tty_port (which will automatically destruct the tty_port when the ref count drops to zero) or it can destruct the tty_port manually. For tty drivers that choose to use the port kref to manage the tty_port lifetime, it is not possible to safely acquire a port reference conditionally. If the last reference is released after evaluating the condition but before acquiring the reference, a bogus reference will be held while the tty_port destruction commences. Rather, only acquire a port reference if the ref count is non-zero and allow the caller to distinguish if a reference has successfully been acquired. Cc: Jiri Slaby <jslaby@suse.cz> Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Tested-By: Alexander Holler <holler@ahsoftware.de> Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
generated by cgit v1.2.3 (git 2.25.1) at 2024-11-18 01:10:17 +0000