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* tty: make n_tty_read() always abort if hangup is in progressTejun Heo2018-02-281-0/+6
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | A tty is hung up by __tty_hangup() setting file->f_op to hung_up_tty_fops, which is skipped on ttys whose write operation isn't tty_write(). This means that, for example, /dev/console whose write op is redirected_tty_write() is never actually marked hung up. Because n_tty_read() uses the hung up status to decide whether to abort the waiting readers, the lack of hung-up marking can lead to the following scenario. 1. A session contains two processes. The leader and its child. The child ignores SIGHUP. 2. The leader exits and starts disassociating from the controlling terminal (/dev/console). 3. __tty_hangup() skips setting f_op to hung_up_tty_fops. 4. SIGHUP is delivered and ignored. 5. tty_ldisc_hangup() is invoked. It wakes up the waits which should clear the read lockers of tty->ldisc_sem. 6. The reader wakes up but because tty_hung_up_p() is false, it doesn't abort and goes back to sleep while read-holding tty->ldisc_sem. 7. The leader progresses to tty_ldisc_lock() in tty_ldisc_hangup() and is now stuck in D sleep indefinitely waiting for tty->ldisc_sem. The following is Alan's explanation on why some ttys aren't hung up. http://lkml.kernel.org/r/20171101170908.6ad08580@alans-desktop 1. It broke the serial consoles because they would hang up and close down the hardware. With tty_port that *should* be fixable properly for any cases remaining. 2. The console layer was (and still is) completely broken and doens't refcount properly. So if you turn on console hangups it breaks (as indeed does freeing consoles and half a dozen other things). As neither can be fixed quickly, this patch works around the problem by introducing a new flag, TTY_HUPPING, which is used solely to tell n_tty_read() that hang-up is in progress for the console and the readers should be aborted regardless of the hung-up status of the device. The following is a sample hung task warning caused by this issue. INFO: task agetty:2662 blocked for more than 120 seconds. Not tainted 4.11.3-dbg-tty-lockup-02478-gfd6c7ee-dirty #28 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. 0 2662 1 0x00000086 Call Trace: __schedule+0x267/0x890 schedule+0x36/0x80 schedule_timeout+0x23c/0x2e0 ldsem_down_write+0xce/0x1f6 tty_ldisc_lock+0x16/0x30 tty_ldisc_hangup+0xb3/0x1b0 __tty_hangup+0x300/0x410 disassociate_ctty+0x6c/0x290 do_exit+0x7ef/0xb00 do_group_exit+0x3f/0xa0 get_signal+0x1b3/0x5d0 do_signal+0x28/0x660 exit_to_usermode_loop+0x46/0x86 do_syscall_64+0x9c/0xb0 entry_SYSCALL64_slow_path+0x25/0x25 The following is the repro. Run "$PROG /dev/console". The parent process hangs in D state. #include <sys/types.h> #include <sys/stat.h> #include <sys/wait.h> #include <sys/ioctl.h> #include <fcntl.h> #include <unistd.h> #include <stdio.h> #include <stdlib.h> #include <errno.h> #include <signal.h> #include <time.h> #include <termios.h> int main(int argc, char **argv) { struct sigaction sact = { .sa_handler = SIG_IGN }; struct timespec ts1s = { .tv_sec = 1 }; pid_t pid; int fd; if (argc < 2) { fprintf(stderr, "test-hung-tty /dev/$TTY\n"); return 1; } /* fork a child to ensure that it isn't already the session leader */ pid = fork(); if (pid < 0) { perror("fork"); return 1; } if (pid > 0) { /* top parent, wait for everyone */ while (waitpid(-1, NULL, 0) >= 0) ; if (errno != ECHILD) perror("waitpid"); return 0; } /* new session, start a new session and set the controlling tty */ if (setsid() < 0) { perror("setsid"); return 1; } fd = open(argv[1], O_RDWR); if (fd < 0) { perror("open"); return 1; } if (ioctl(fd, TIOCSCTTY, 1) < 0) { perror("ioctl"); return 1; } /* fork a child, sleep a bit and exit */ pid = fork(); if (pid < 0) { perror("fork"); return 1; } if (pid > 0) { nanosleep(&ts1s, NULL); printf("Session leader exiting\n"); exit(0); } /* * The child ignores SIGHUP and keeps reading from the controlling * tty. Because SIGHUP is ignored, the child doesn't get killed on * parent exit and the bug in n_tty makes the read(2) block the * parent's control terminal hangup attempt. The parent ends up in * D sleep until the child is explicitly killed. */ sigaction(SIGHUP, &sact, NULL); printf("Child reading tty\n"); while (1) { char buf[1024]; if (read(fd, buf, sizeof(buf)) < 0) { perror("read"); return 1; } } return 0; } Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Alan Cox <alan@llwyncelyn.cymru> Cc: stable@vger.kernel.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* vfs: do bulk POLL* -> EPOLL* replacementLinus Torvalds2018-02-111-8/+8
| | | | | | | | | | | | | | | | | | | | | | | This is the mindless scripted replacement of kernel use of POLL* variables as described by Al, done by this script: for V in IN OUT PRI ERR RDNORM RDBAND WRNORM WRBAND HUP RDHUP NVAL MSG; do L=`git grep -l -w POLL$V | grep -v '^t' | grep -v /um/ | grep -v '^sa' | grep -v '/poll.h$'|grep -v '^D'` for f in $L; do sed -i "-es/^\([^\"]*\)\(\<POLL$V\>\)/\\1E\\2/" $f; done done with de-mangling cleanups yet to come. NOTE! On almost all architectures, the EPOLL* constants have the same values as the POLL* constants do. But they keyword here is "almost". For various bad reasons they aren't the same, and epoll() doesn't actually work quite correctly in some cases due to this on Sparc et al. The next patch from Al will sort out the final differences, and we should be all done. Scripted-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Merge branch 'misc.poll' of ↵Linus Torvalds2018-01-301-2/+2
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs Pull poll annotations from Al Viro: "This introduces a __bitwise type for POLL### bitmap, and propagates the annotations through the tree. Most of that stuff is as simple as 'make ->poll() instances return __poll_t and do the same to local variables used to hold the future return value'. Some of the obvious brainos found in process are fixed (e.g. POLLIN misspelled as POLL_IN). At that point the amount of sparse warnings is low and most of them are for genuine bugs - e.g. ->poll() instance deciding to return -EINVAL instead of a bitmap. I hadn't touched those in this series - it's large enough as it is. Another problem it has caught was eventpoll() ABI mess; select.c and eventpoll.c assumed that corresponding POLL### and EPOLL### were equal. That's true for some, but not all of them - EPOLL### are arch-independent, but POLL### are not. The last commit in this series separates userland POLL### values from the (now arch-independent) kernel-side ones, converting between them in the few places where they are copied to/from userland. AFAICS, this is the least disruptive fix preserving poll(2) ABI and making epoll() work on all architectures. As it is, it's simply broken on sparc - try to give it EPOLLWRNORM and it will trigger only on what would've triggered EPOLLWRBAND on other architectures. EPOLLWRBAND and EPOLLRDHUP, OTOH, are never triggered at all on sparc. With this patch they should work consistently on all architectures" * 'misc.poll' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (37 commits) make kernel-side POLL... arch-independent eventpoll: no need to mask the result of epi_item_poll() again eventpoll: constify struct epoll_event pointers debugging printk in sg_poll() uses %x to print POLL... bitmap annotate poll(2) guts 9p: untangle ->poll() mess ->si_band gets POLL... bitmap stored into a user-visible long field ring_buffer_poll_wait() return value used as return value of ->poll() the rest of drivers/*: annotate ->poll() instances media: annotate ->poll() instances fs: annotate ->poll() instances ipc, kernel, mm: annotate ->poll() instances net: annotate ->poll() instances apparmor: annotate ->poll() instances tomoyo: annotate ->poll() instances sound: annotate ->poll() instances acpi: annotate ->poll() instances crypto: annotate ->poll() instances block: annotate ->poll() instances x86: annotate ->poll() instances ...
| * the rest of drivers/*: annotate ->poll() instancesAl Viro2017-11-281-2/+2
| | | | | | | | Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* | n_tty: fix EXTPROC vs ICANON interaction with TIOCINQ (aka FIONREAD)Linus Torvalds2017-12-211-2/+2
|/ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | We added support for EXTPROC back in 2010 in commit 26df6d13406d ("tty: Add EXTPROC support for LINEMODE") and the intent was to allow it to override some (all?) ICANON behavior. Quoting from that original commit message: There is a new bit in the termios local flag word, EXTPROC. When this bit is set, several aspects of the terminal driver are disabled. Input line editing, character echo, and mapping of signals are all disabled. This allows the telnetd to turn off these functions when in linemode, but still keep track of what state the user wants the terminal to be in. but the problem turns out that "several aspects of the terminal driver are disabled" is a bit ambiguous, and you can really confuse the n_tty layer by setting EXTPROC and then causing some of the ICANON invariants to no longer be maintained. This fixes at least one such case (TIOCINQ) becoming unhappy because of the confusion over whether ICANON really means ICANON when EXTPROC is set. This basically makes TIOCINQ match the case of read: if EXTPROC is set, we ignore ICANON. Also, make sure to reset the ICANON state ie EXTPROC changes, not just if ICANON changes. Fixes: 26df6d13406d ("tty: Add EXTPROC support for LINEMODE") Reported-by: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp> Reported-by: syzkaller <syzkaller@googlegroups.com> Cc: Jiri Slaby <jslaby@suse.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: Remove redundant license textGreg Kroah-Hartman2017-11-081-3/+0
| | | | | | | | | | | | | | | | | Now that the SPDX tag is in all tty files, that identifies the license in a specific and legally-defined manner. So the extra GPL text wording can be removed as it is no longer needed at all. This is done on a quest to remove the 700+ different ways that files in the kernel describe the GPL license text. And there's unneeded stuff like the address (sometimes incorrect) for the FSF which is never needed. No copyright headers or other non-license-description text was removed. Cc: Jiri Slaby <jslaby@suse.com> Cc: James Hogan <jhogan@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: add SPDX identifiers to all remaining files in drivers/tty/Greg Kroah-Hartman2017-11-081-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | It's good to have SPDX identifiers in all files to make it easier to audit the kernel tree for correct licenses. Update the drivers/tty files files with the correct SPDX license identifier based on the license text in the file itself. The SPDX identifier is a legally binding shorthand, which can be used instead of the full boiler plate text. This work is based on a script and data from Thomas Gleixner, Philippe Ombredanne, and Kate Stewart. Cc: Jiri Slaby <jslaby@suse.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Chris Metcalf <cmetcalf@mellanox.com> Cc: Jiri Kosina <jikos@kernel.org> Cc: David Sterba <dsterba@suse.com> Cc: James Hogan <jhogan@kernel.org> Cc: Rob Herring <robh@kernel.org> Cc: Eric Anholt <eric@anholt.net> Cc: Stefan Wahren <stefan.wahren@i2se.com> Cc: Florian Fainelli <f.fainelli@gmail.com> Cc: Ray Jui <rjui@broadcom.com> Cc: Scott Branden <sbranden@broadcom.com> Cc: bcm-kernel-feedback-list@broadcom.com Cc: "James E.J. Bottomley" <jejb@parisc-linux.org> Cc: Helge Deller <deller@gmx.de> Cc: Joachim Eastwood <manabian@gmail.com> Cc: Matthias Brugger <matthias.bgg@gmail.com> Cc: Masahiro Yamada <yamada.masahiro@socionext.com> Cc: Tobias Klauser <tklauser@distanz.ch> Cc: Russell King <linux@armlinux.org.uk> Cc: Vineet Gupta <vgupta@synopsys.com> Cc: Richard Genoud <richard.genoud@gmail.com> Cc: Alexander Shiyan <shc_work@mail.ru> Cc: Baruch Siach <baruch@tkos.co.il> Cc: "Maciej W. Rozycki" <macro@linux-mips.org> Cc: "Uwe Kleine-König" <kernel@pengutronix.de> Cc: Pat Gefre <pfg@sgi.com> Cc: "Guilherme G. Piccoli" <gpiccoli@linux.vnet.ibm.com> Cc: Jason Wessel <jason.wessel@windriver.com> Cc: Vladimir Zapolskiy <vz@mleia.com> Cc: Sylvain Lemieux <slemieux.tyco@gmail.com> Cc: Carlo Caione <carlo@caione.org> Cc: Kevin Hilman <khilman@baylibre.com> Cc: Liviu Dudau <liviu.dudau@arm.com> Cc: Sudeep Holla <sudeep.holla@arm.com> Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> Cc: Andy Gross <andy.gross@linaro.org> Cc: David Brown <david.brown@linaro.org> Cc: "Andreas Färber" <afaerber@suse.de> Cc: Kevin Cernekee <cernekee@gmail.com> Cc: Laxman Dewangan <ldewangan@nvidia.com> Cc: Thierry Reding <thierry.reding@gmail.com> Cc: Jonathan Hunter <jonathanh@nvidia.com> Cc: Barry Song <baohua@kernel.org> Cc: Patrice Chotard <patrice.chotard@st.com> Cc: Maxime Coquelin <mcoquelin.stm32@gmail.com> Cc: Alexandre Torgue <alexandre.torgue@st.com> Cc: "David S. Miller" <davem@davemloft.net> Cc: Peter Korsgaard <jacmet@sunsite.dk> Cc: Timur Tabi <timur@tabi.org> Cc: Tony Prisk <linux@prisktech.co.nz> Cc: Michal Simek <michal.simek@xilinx.com> Cc: "Sören Brinkmann" <soren.brinkmann@xilinx.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Kate Stewart <kstewart@linuxfoundation.org> Cc: Philippe Ombredanne <pombredanne@nexb.com> Cc: Jiri Slaby <jslaby@suse.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* Fix OpenSSH pty regression on closeBrian Bloniarz2016-05-011-37/+33
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | OpenSSH expects the (non-blocking) read() of pty master to return EAGAIN only if it has received all of the slave-side output after it has received SIGCHLD. This used to work on pre-3.12 kernels. This fix effectively forces non-blocking read() and poll() to block for parallel i/o to complete for all ttys. It also unwinds these changes: 1) f8747d4a466ab2cafe56112c51b3379f9fdb7a12 tty: Fix pty master read() after slave closes 2) 52bce7f8d4fc633c9a9d0646eef58ba6ae9a3b73 pty, n_tty: Simplify input processing on final close 3) 1a48632ffed61352a7810ce089dc5a8bcd505a60 pty: Fix input race when closing Inspired by analysis and patch from Marc Aurele La France <tsi@tuyoix.net> Reported-by: Volth <openssh@volth.com> Reported-by: Marc Aurele La France <tsi@tuyoix.net> BugLink: https://bugzilla.mindrot.org/show_bug.cgi?id=52 BugLink: https://bugzilla.mindrot.org/show_bug.cgi?id=2492 Signed-off-by: Brian Bloniarz <brian.bloniarz@gmail.com> Reviewed-by: Peter Hurley <peter@hurleysoftware.com> Cc: stable <stable@vger.kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* n_tty: Ignore all read data when closingPeter Hurley2016-01-281-2/+0
| | | | | | | | | On final port close (and thus final tty close), only output flow control requests in the input data should be processed. Ignore all other input data, including parity errors, overruns and breaks. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: n_tty: fix SIGIO for outputPeter Hurley2016-01-281-1/+1
| | | | | | | | | | | | | | | | | | | According to fcntl(2), "a SIGIO signal is sent whenever input or output becomes possible on that file descriptor", i.e. after the output buffer was full and now has space for new data. But in fact SIGIO is sent after every write. n_tty_write() should set TTY_DO_WRITE_WAKEUP only when not all data could be written to the buffer. [pjh: Also fixes missed SIGIO if amt written just happens to be [ amount still to write Signed-off-by: Johannes Stezenbach <js@sig21.net> [pjh: minor patch edits and re-submit] Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* n_tty: Remove tty count checks from unthrottlePeter Hurley2016-01-281-4/+0
| | | | | | | | | | Since n_tty_check_unthrottle() is only called from n_tty_read() which only originates from a userspace read(), the tty count cannot be 0; the read() guarantees the file descriptor has not yet been released. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* n_tty: Fix stuck write wakeupPeter Hurley2016-01-281-2/+2
| | | | | | | | | | | | | | If signal-driven i/o is disabled while write wakeup is pending (ie., n_tty_write() has set TTY_DO_WRITE_WAKEUP but then signal-driven i/o is disabled), the TTY_DO_WRITE_WAKEUP bit will never be cleared and will cause tty_wakeup() to always call n_tty_write_wakeup. Unconditionally clear the write wakeup, and since kill_fasync() already checks if the fasync ptr is null, call kill_fasync() unconditionally as well. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty, n_tty: Remove fasync() ldisc notificationPeter Hurley2016-01-281-5/+0
| | | | | | | | | | | | | | | | | | | | | | | Only the N_TTY line discipline implements the signal-driven i/o notification enabled/disabled by fcntl(F_SETFL, O_ASYNC). The ldisc fasync() notification is sent to the ldisc when the enable state has changed (the tty core is notified via the fasync() VFS file operation). The N_TTY line discipline used the enable state to change the wakeup condition (minimum_to_wake = 1) for notifying the signal handler i/o is available. However, just the presence of data is sufficient and necessary to signal i/o is available, so changing minimum_to_wake is unnecessary (and creates a race condition with read() and poll() which may be concurrently updating minimum_to_wake). Furthermore, since the kill_fasync() VFS helper performs no action if the fasync list is empty, calling unconditionally is preferred; if signal driven i/o just has been disabled, no signal will be sent by kill_fasync() anyway so notification of the change via the ldisc fasync() method is superfluous. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* n_tty: Always wake up read()/poll() if new inputPeter Hurley2016-01-281-32/+2
| | | | | | | | | | | | | | | | | | | | A read() in non-canonical mode when VMIN > 0 and VTIME == 0 does not complete until at least VMIN chars have been read (or the user buffer is full). In this infrequent read mode, n_tty_read() attempts to reduce wakeups by computing the amount of data still necessary to complete the read (minimum_to_wake) and only waking the read()/poll() when that much unread data has been processed. This is the only read mode for which new data does not necessarily generate a wakeup. However, this optimization is broken and commonly leads to hung reads even though the necessary amount of data has been received. Since the optimization is of marginal value anyway, just remove the whole thing. This also remedies a race between a concurrent poll() and read() in this mode, where the poll() can reset the minimum_to_wake of the read() (and vice versa). Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: audit: Ignore current association for audit pushPeter Hurley2016-01-271-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | In canonical read mode, each line read and logged is pushed separately with tty_audit_push(). For all single-threaded processes and multi-threaded processes reading from only one tty, this patch has no effect; the last line read will still be the entry pushed to the audit log because the tty association cannot have changed between tty_audit_add_data() and tty_audit_push(). For multi-threaded processes reading from different ttys concurrently, the audit log will have mixed log entries anyway. Consider two ttys audited concurrently: CPU0 CPU1 ---------- ------------ tty_audit_add_data(ttyA) tty_audit_add_data(ttyB) tty_audit_push() tty_audit_add_data(ttyB) tty_audit_push() This patch will now cause the ttyB output to be split into separate audit log entries. However, this possibility is equally likely without this patch: CPU0 CPU1 ---------- ------------ tty_audit_add_data(ttyB) tty_audit_add_data(ttyA) tty_audit_push() tty_audit_add_data(ttyB) tty_audit_push() Mixed canonical and non-canonical reads have similar races. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: audit: Remove icanon mode from call chainPeter Hurley2016-01-271-3/+3
| | | | | | | | | | | | | | The tty termios bits cannot change while n_tty_read() is in the i/o loop; the termios_rwsem ensures mutual exclusion with termios changes in n_tty_set_termios(). Check L_ICANON() directly and eliminate icanon parameter. NB: tty_audit_add_data() => tty_audit_buf_get() => tty_audit_buf_alloc() is a single path; ie., tty_audit_buf_get() and tty_audit_buf_alloc() have no other callers. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: audit: Never audit packet modePeter Hurley2016-01-271-13/+4
| | | | | | | | | | | | tty audit never logs pty master reads, but packet mode only works for pty masters, so tty_audit_add_data() was never logging packet mode anyway. Don't audit packet mode data. As those are the lone call sites, remove tty_put_user(). Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: Move tty_check_change() helperPeter Hurley2016-01-271-6/+0
| | | | | | | | Move is_ignored() to drivers/tty/tty_io.c and re-declare in file scope. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: Eliminate global symbol tty_ldisc_N_TTYPeter Hurley2016-01-271-4/+8
| | | | | | | | Reduce global tty symbols; move and rename tty_ldisc_begin() as n_tty_init() and redefine the N_TTY ldisc ops as file scope. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: Remove chars_in_buffer() line discipline methodPeter Hurley2016-01-271-23/+0
| | | | | | | | | | | | The chars_in_buffer() line discipline method serves no functional purpose, other than as a (dubious) debugging aid for mostly bit-rotting drivers. Despite being documented as an optional method, every caller is unconditionally executed (although conditionally compiled). Furthermore, direct tty->ldisc access without an ldisc ref is unsafe. Lastly, N_TTY's chars_in_buffer() has warned of removal since 3.12. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* n_tty: Fix unsafe reference to "other" ldiscPeter Hurley2016-01-261-5/+2
| | | | | | | | | | | | | Although n_tty_check_unthrottle() has a valid ldisc reference (since the tty core gets the ldisc ref in tty_read() before calling the line discipline read() method), it does not have a valid ldisc reference to the "other" pty of a pty pair. Since getting an ldisc reference for tty->link essentially open-codes tty_wakeup(), just replace with the equivalent tty_wakeup(). Cc: <stable@vger.kernel.org> Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* Merge 4.4-rc6 into tty-nextGreg Kroah-Hartman2015-12-211-13/+9
|\ | | | | | | | | | | We want the serial/tty fixes in here as well. Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| * n_tty: Fix poll() after buffer-limited eof push readPeter Hurley2015-12-121-13/+9
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | commit 40d5e0905a03 ("n_tty: Fix EOF push handling") fixed EOF push for reads. However, that approach still allows a condition mismatch between poll() and read(), where poll() returns POLLIN but read() blocks. This state can happen when a previous read() returned because the user buffer was full and the next character was an EOF not at the beginning of the line. While the next read() will properly identify the condition and advance the read buffer tail without improperly indicating an EOF file condition (ie., read() will not mistakenly return 0), poll() will mistakenly indicate POLLIN. Although a possible solution would be to peek at the input buffer in n_tty_poll(), the better solution in this patch is to eat the EOF during the previous read() (ie., fix the problem by eliminating the condition). The current canon line buffer copy limits the scan for next end-of-line to the smaller of either, a. the remaining user buffer size b. completed lines in the input buffer When the remaining user buffer size is exactly one less than the end-of-line marked by EOF push, the EOF is not scanned nor skipped but left for subsequent reads. In the example below, the scan index 'eol' has stopped at the EOF because it is past the scan limit of 5 (not because it has found the next set bit in read_flags) user buffer [*nr = 5] _ _ _ _ _ read_flags 0 0 0 0 0 1 input buffer h e l l o [EOF] ^ ^ / / tail eol result: found = 0, tail += 5, *nr += 5 Instead, allow the scan to peek ahead 1 byte (while still limiting the scan to completed lines in the input buffer). For the example above, result: found = 1, tail += 6, *nr += 5 Because the scan limit is now bumped +1 byte, when the scan is completed, the tail advance and the user buffer copy limit is re-clamped to *nr when EOF is _not_ found. Fixes: 40d5e0905a03 ("n_tty: Fix EOF push handling") Cc: <stable@vger.kernel.org> # 3.12+ Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* | n_tty: Reduce branching in canon_copy_from_read_buf()Peter Hurley2015-12-131-4/+3
| | | | | | | | | | | | | | Instead of compare-and-set, just compute 'found'. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* | n_tty: Clarify copy_from_read_buf()Peter Hurley2015-12-131-4/+4
| | | | | | | | | | | | | | | | Add a temporary for the computed source address and substitute where appropriate. No functional change. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* | n_tty: Uninline tty_copy_to_user()Peter Hurley2015-12-131-15/+18
| | | | | | | | | | | | | | | | Merge the multiple tty_copy_to_user() calls into a single copy sequence within tty_copy_to_user(). Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* | tty: Define tty_*() printk macrosPeter Hurley2015-12-131-5/+2
|/ | | | | | | | | | | | | 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: audit: Fix audit sourcePeter Hurley2015-11-201-1/+1
| | | | | | | | | | | | 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 Hurley2015-10-171-1/+1
| | | | | | | | 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 Hurley2015-10-171-24/+2
| | | | | | | | | | | | | | 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>
* n_tty: Remove reader wakeups for TTY_BREAK/TTY_PARITY charsPeter Hurley2015-10-171-4/+0
| | | | | | | | | | | | | | | | | | | | | Waking the reader immediately upon receipt of TTY_BREAK or TTY_PARITY chars has no effect on the outcome of read(): 1. Only non-canonical/EXTPROC mode applies since canonical mode will not return data until a line termination is received anyway 2. EXTPROC mode - the reader will always be woken by the input worker 3. Non-canonical modes a. MIN == 0, TIME == 0 b. MIN == 0, TIME > 0 c. MIN > 0, TIME > 0 minimum_to_wake is always 1 in these modes so the reader will always be woken by the input worker d. MIN > 0, TIME == 0 although the reader will not be woken by the input worker unless the minimum data is received, the reader would not otherwise have returned the received data Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: fix stall caused by missing memory barrier in drivers/tty/n_tty.cKosuke Tatsukawa2015-10-041-10/+5
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | My colleague ran into a program stall on a x86_64 server, where n_tty_read() was waiting for data even if there was data in the buffer in the pty. kernel stack for the stuck process looks like below. #0 [ffff88303d107b58] __schedule at ffffffff815c4b20 #1 [ffff88303d107bd0] schedule at ffffffff815c513e #2 [ffff88303d107bf0] schedule_timeout at ffffffff815c7818 #3 [ffff88303d107ca0] wait_woken at ffffffff81096bd2 #4 [ffff88303d107ce0] n_tty_read at ffffffff8136fa23 #5 [ffff88303d107dd0] tty_read at ffffffff81368013 #6 [ffff88303d107e20] __vfs_read at ffffffff811a3704 #7 [ffff88303d107ec0] vfs_read at ffffffff811a3a57 #8 [ffff88303d107f00] sys_read at ffffffff811a4306 #9 [ffff88303d107f50] entry_SYSCALL_64_fastpath at ffffffff815c86d7 There seems to be two problems causing this issue. First, in drivers/tty/n_tty.c, __receive_buf() stores the data and updates ldata->commit_head using smp_store_release() and then checks the wait queue using waitqueue_active(). However, since there is no memory barrier, __receive_buf() could return without calling wake_up_interactive_poll(), and at the same time, n_tty_read() could start to wait in wait_woken() as in the following chart. __receive_buf() n_tty_read() ------------------------------------------------------------------------ if (waitqueue_active(&tty->read_wait)) /* Memory operations issued after the RELEASE may be completed before the RELEASE operation has completed */ add_wait_queue(&tty->read_wait, &wait); ... if (!input_available_p(tty, 0)) { smp_store_release(&ldata->commit_head, ldata->read_head); ... timeout = wait_woken(&wait, TASK_INTERRUPTIBLE, timeout); ------------------------------------------------------------------------ The second problem is that n_tty_read() also lacks a memory barrier call and could also cause __receive_buf() to return without calling wake_up_interactive_poll(), and n_tty_read() to wait in wait_woken() as in the chart below. __receive_buf() n_tty_read() ------------------------------------------------------------------------ spin_lock_irqsave(&q->lock, flags); /* from add_wait_queue() */ ... if (!input_available_p(tty, 0)) { /* Memory operations issued after the RELEASE may be completed before the RELEASE operation has completed */ smp_store_release(&ldata->commit_head, ldata->read_head); if (waitqueue_active(&tty->read_wait)) __add_wait_queue(q, wait); spin_unlock_irqrestore(&q->lock,flags); /* from add_wait_queue() */ ... timeout = wait_woken(&wait, TASK_INTERRUPTIBLE, timeout); ------------------------------------------------------------------------ There are also other places in drivers/tty/n_tty.c which have similar calls to waitqueue_active(), so instead of adding many memory barrier calls, this patch simply removes the call to waitqueue_active(), leaving just wake_up*() behind. This fixes both problems because, even though the memory access before or after the spinlocks in both wake_up*() and add_wait_queue() can sneak into the critical section, it cannot go past it and the critical section assures that they will be serialized (please see "INTER-CPU ACQUIRING BARRIER EFFECTS" in Documentation/memory-barriers.txt for a better explanation). Moreover, the resulting code is much simpler. Latency measurement using a ping-pong test over a pty doesn't show any visible performance drop. Signed-off-by: Kosuke Tatsukawa <tatsu@ab.jp.nec.com> Cc: stable@vger.kernel.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* Merge 4.2-rc4 into tty-nextGreg Kroah-Hartman2015-07-271-3/+13
|\ | | | | | | | | | | | | Other serial driver work wants to build on patches now in 4.2-rc4 so merge the branch so this can properly happen. Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| * n_tty: signal and flush atomicallyPeter Hurley2015-07-231-3/+13
| | | | | | | | | | | | | | | | | | | | | | | | | | | | When handling signalling char, claim the termios write lock before signalling waiting readers and writers to prevent further i/o before flushing the echo and output buffers. This prevents a userspace signal handler which may output from racing the terminal flush. Reference: Bugzilla #99351 ("Output truncated in ssh session after...") Fixes: commit d2b6f44779d3 ("n_tty: Fix signal handling flushes") Reported-by: Filipe Brandenburger <filbranden@google.com> Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* | tty: add missing rcu_read_lock for task_pgrpPatrick Donnelly2015-07-231-3/+12
|/ | | | | | | | | | task_pgrp requires an rcu or tasklist lock to be obtained if the returned pid is to be dereferenced, which kill_pgrp does. Obtain an RCU lock for the duration of use. Signed-off-by: Patrick Donnelly <batrick@batbytes.com> Reviewed-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* Merge 4.1-rc7 into tty-nextGreg Kroah-Hartman2015-06-081-5/+16
|\ | | | | | | | | | | | | This fixes up a merge issue with the amba-pl011.c driver, and we want the fixes in this branch as well. Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| * n_tty: Fix auditing support for cannonical modeLaura Abbott2015-06-011-3/+14
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Commit 32f13521ca68bc624ff6effc77f308a52b038bf0 ("n_tty: Line copy to user buffer in canonical mode") changed cannonical mode copying to use copy_to_user but missed adding the call to the audit framework. Add in the appropriate functions to get audit support. Fixes: 32f13521ca68 ("n_tty: Line copy to user buffer in canonical mode") Reported-by: Miloslav Trmač <mitr@redhat.com> Signed-off-by: Laura Abbott <labbott@fedoraproject.org> Reviewed-by: Peter Hurley <peter@hurleysoftware.com> Cc: stable <stable@vger.kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| * n_tty: Fix calculation of size in canon_copy_from_read_bufMark Tomlinson2015-05-241-2/+2
| | | | | | | | | | | | | | | | | | | | There was a hardcoded value of 4096 which should have been N_TTY_BUF_SIZE. This caused reads from tty to fail with EFAULT when they shouldn't have done if N_TTY_BUF_SIZE was declared to be something other than 4096. Signed-off-by: Mark Tomlinson <mark.tomlinson@alliedtelesis.co.nz> Reviewed-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* | Merge 4.1-rc4 into tty-nextGreg Kroah-Hartman2015-05-181-4/+18
|\| | | | | | | | | | | This resolves some tty driver merge issues. Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| * pty: Fix input race when closingPeter Hurley2015-05-101-4/+18
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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 Villemoes2015-05-061-5/+2
|/ | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
* n_tty: Fix signal handling flushesPeter Hurley2015-02-021-15/+30
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
* n_tty: Fix read buffer overwrite when no newlinePeter Hurley2015-02-021-30/+62
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | In canon mode, the read buffer head will advance over the buffer tail if the input > 4095 bytes without receiving a line termination char. Discard additional input until a line termination is received. Before evaluating for overflow, the 'room' value is normalized for I_PARMRK and 1 byte is reserved for line termination (even in !icanon mode, in case the mode is switched). The following table shows the transform: actual buffer | 'room' value before overflow calc space avail | !I_PARMRK | I_PARMRK -------------------------------------------------- 0 | -1 | -1 1 | 0 | 0 2 | 1 | 0 3 | 2 | 0 4+ | 3 | 1 When !icanon or when icanon and the read buffer contains newlines, normalized 'room' values of -1 and 0 are clamped to 0, and 'overflow' is 0, so read_head is not adjusted and the input i/o loop exits (setting no_room if called from flush_to_ldisc()). No input is discarded since the reader does have input available to read which ensures forward progress. When icanon and the read buffer does not contain newlines and the normalized 'room' value is 0, then overflow and room are reset to 1, so that the i/o loop will process the next input char normally (except for parity errors which are ignored). Thus, erasures, signalling chars, 7-bit mode, etc. will continue to be handled properly. If the input char processed was not a line termination char, then the canon_head index will not have advanced, so the normalized 'room' value will now be -1 and 'overflow' will be set, which indicates the read_head can safely be reset, effectively erasing the last char processed. If the input char processed was a line termination, then the canon_head index will have advanced, so 'overflow' is cleared to 0, the read_head is not reset, and 'room' is cleared to 0, which exits the i/o loop (because the reader now have input available to read which ensures forward progress). Note that it is possible for a line termination to be received, and for the reader to copy the line to the user buffer before the input i/o loop is ready to process the next input char. This is why the i/o loop recomputes the room/overflow state with every input char while handling overflow. Finally, if the input data was processed without receiving a line termination (so that overflow is still set), the pty driver must receive a write wakeup. A pty writer may be waiting to write more data in n_tty_write() but without unthrottling here that wakeup will not arrive, and forward progress will halt. (Normally, the pty writer is woken when the reader reads data out of the buffer and more space become available). Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* n_tty: Fix PARMRK over-throttlingPeter Hurley2015-02-021-8/+4
| | | | | | | | | | | | | | | | | | | If PARMRK is enabled, the available read buffer space computation is overly-pessimistic, which results in severely throttled i/o, even in the absence of parity errors. For example, if the 4k read buffer contains 1k processed data, the input worker will compute available space of 333 bytes, despite 3k being available. At 1365 chars of processed data, 0 space available is computed. *Divide remaining space* by 3, truncating down (if left == 2, left = 0). Reported-by: Christian Riesch <christian.riesch@omicron.at> Conflicts: drivers/tty/n_tty.c Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* n_tty: Fix unordered accesses to lockless read bufferPeter Hurley2015-02-021-53/+48
| | | | | | | | | | | | | | | | | | | | | Add commit_head buffer index, which the producer-side publishes after input processing in non-canon mode. This ensures the consumer-side observes correctly-ordered writes in non-canonical mode (ie., the buffer data is written before the buffer index is advanced). Fix consumer-side uses of read_cnt() to use commit_head instead. Add required memory barriers to the tail index to guarantee the consumer-side has completed the loads before the producer-side begins writing new data. Open-code the producer-side receive_room() into the i/o loop. Remove no-longer-referenced receive_room(). Based on work by Christian Riesch <christian.riesch@omicron.at> Cc: Christian Riesch <christian.riesch@omicron.at> Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* n_tty: Simplify throttle threshold calculationPeter Hurley2015-02-021-1/+1
| | | | | | | | | | The adjustments performed by receive_room() are to ensure a line termination can always be written to the read buffer. However, these adjustments are irrelevant to the throttle threshold (because the threshold < buffer limit). Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* n_tty: Fix throttle for canon lines > 3967 charsPeter Hurley2015-02-021-0/+5
| | | | | | | | | | | | | The tty driver will be mistakenly throttled if a line termination has not been received, and the line exceeds 3967 chars. Thus, it is possible for the driver to stop sending when it has not yet sent the newline. This does not apply to the pty driver. Don't throttle until at least one line termination has been received. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* n_tty: Eliminate receive_room() from consumer/exclusive pathsPeter Hurley2015-02-021-11/+12
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | The input worker never reschedules itself; it only processes input until either there is no more input or the read buffer is full. So the reader is responsible for restarting the input worker only if the read buffer was previously full (no_room == 1) _and_ space is now available to process more input because the reader has consumed data from the read buffer. However, computing the actual space available is not required to determine if the reader has consumed data from the read buffer. This condition is evaluated in 5 situations, each of which the space avail is already known: 1. n_tty_flush_buffer() - the read buffer is empty; kick the worker 2. n_tty_set_termios() - no data has been consumed; do not kick the worker (although it may have kicked the reader so data _will be_ consumed) 3. n_tty_check_unthrottle - avail space > 3968; kick the worker 4. n_tty_read, before leaving - only kick the worker if the reader has moved the tail. This prevents unnecessarily kicking the worker when timeout-style reading is used. 5. n_tty_read, before sleeping - although it is possible for the read buffer to be full and input_available_p() to be false, this can only happen when the input worker is racing the reader, in which case the reader will have been woken and won't sleep. Rename n_tty_set_room() to n_tty_kick_worker() to reflect what the function actually does. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* Revert "tty: Fix pty master poll() after slave closes v2"Peter Hurley2015-01-091-7/+2
| | | | | | | | | | | | | | This reverts commit c4dc304677e8d566572c4738d95c48be150c6606. This fix is superseded by commit 52bce7f8d4fc633c9a9d0646eef58ba6ae9a3b73, 'pty, n_tty: Simplify input processing on final close'. The final close now waits for input processing to complete before destroying the pty, so poll() does not need to special case this condition. Cc: Francesco Ruggeri <fruggeri@arista.com> Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* Merge tag 'tty-3.19-rc1' of ↵Linus Torvalds2014-12-141-44/+37
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty Pull tty/serial driver updates from Greg KH: "Here's the big tty/serial driver update for 3.19-rc1. There are a number of TTY core changes/fixes in here from Peter Hurley that have all been teted in linux-next for a long time now. There are also the normal serial driver updates as well, full details in the changelog below" * tag 'tty-3.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty: (219 commits) serial: pxa: hold port.lock when reporting modem line changes tty-hvsi_lib: Deletion of an unnecessary check before the function call "tty_kref_put" tty: Deletion of unnecessary checks before two function calls n_tty: Fix read_buf race condition, increment read_head after pushing data serial: of-serial: add PM suspend/resume support Revert "serial: of-serial: add PM suspend/resume support" Revert "serial: of-serial: fix up PM ops on no_console_suspend and port type" serial: 8250: don't attempt a trylock if in sysrq serial: core: Add big-endian iotype serial: samsung: use port->fifosize instead of hardcoded values serial: samsung: prefer to use fifosize from driver data serial: samsung: fix style problems serial: samsung: wait for transfer completion before clock disable serial: icom: fix error return code serial: tegra: clean up tty-flag assignments serial: Fix io address assign flow with Fintek PCI-to-UART Product serial: mxs-auart: fix tx_empty against shift register serial: mxs-auart: fix gpio change detection on interrupt serial: mxs-auart: Fix mxs_auart_set_ldisc() serial: 8250_dw: Use 64-bit access for OCTEON. ...