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path: root/drivers/tty/n_tty.c (follow)
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2013-05-20TTY: Fix tty miss restart after we turn off flow-controlWang YanQing1-0/+8
I meet emacs hang in start if I do the operation below: 1: echo 3 > /proc/sys/vm/drop_caches 2: emacs BigFile 3: Press CTRL-S follow 2 immediately Then emacs hang on, CTRL-Q can't resume, the terminal hang on, you can do nothing with this terminal except close it. The reason is before emacs takeover control the tty, we use CTRL-S to XOFF it. Then when emacs takeover the control, it may don't use the flow-control, so emacs hang. This patch fix it. This patch will fix a kind of strange tty relation hang problem, I believe I meet it with vim in ssh, and also see below bug report: http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=465823 Signed-off-by: Wang YanQing <udknight@gmail.com> Cc: stable <stable@vger.kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-03-18n_tty: Fully initialize ldisc before restarting buffer workPeter Hurley1-9/+8
Buffer work may already be pending when the n_tty ldisc is re-opened, eg., when setting the ldisc (via TIOCSETD ioctl) and when hanging up the tty. Since n_tty_set_room() may restart buffer work, first ensure the ldisc is completely initialized. Factor n_tty_set_room() out of reset_buffer_flags() (only 2 callers) and reorganize n_tty_open() to set termios last; buffer work will be restarted there if necessary, after the char_map is properly initialized. Fixes this WARNING: [ 549.561769] ------------[ cut here ]------------ [ 549.598755] WARNING: at drivers/tty/n_tty.c:160 n_tty_set_room+0xff/0x130() [ 549.604058] scheduling buffer work for halted ldisc [ 549.607741] Pid: 9417, comm: trinity-child28 Tainted: G D W 3.7.0-next-20121217-sasha-00023-g8689ef9 #219 [ 549.652580] Call Trace: [ 549.662754] [<ffffffff81c432cf>] ? n_tty_set_room+0xff/0x130 [ 549.665458] [<ffffffff8110cae7>] warn_slowpath_common+0x87/0xb0 [ 549.668257] [<ffffffff8110cb71>] warn_slowpath_fmt+0x41/0x50 [ 549.671007] [<ffffffff81c432cf>] n_tty_set_room+0xff/0x130 [ 549.673268] [<ffffffff81c44597>] reset_buffer_flags+0x137/0x150 [ 549.675607] [<ffffffff81c45b71>] n_tty_open+0x131/0x1c0 [ 549.677699] [<ffffffff81c47824>] tty_ldisc_open.isra.5+0x54/0x70 [ 549.680147] [<ffffffff81c482bf>] tty_ldisc_hangup+0x11f/0x1e0 [ 549.682409] [<ffffffff81c3fa17>] __tty_hangup+0x137/0x440 [ 549.684634] [<ffffffff81c3fd49>] tty_vhangup+0x9/0x10 [ 549.686443] [<ffffffff81c4a42c>] pty_close+0x14c/0x160 [ 549.688446] [<ffffffff81c41225>] tty_release+0xd5/0x490 [ 549.690460] [<ffffffff8127d8a2>] __fput+0x122/0x250 [ 549.692577] [<ffffffff8127d9d9>] ____fput+0x9/0x10 [ 549.694534] [<ffffffff811348c2>] task_work_run+0xb2/0xf0 [ 549.696349] [<ffffffff81113c6d>] do_exit+0x36d/0x580 [ 549.698286] [<ffffffff8107d964>] ? syscall_trace_enter+0x24/0x2e0 [ 549.702729] [<ffffffff81113f4a>] do_group_exit+0x8a/0xc0 [ 549.706775] [<ffffffff81113f92>] sys_exit_group+0x12/0x20 [ 549.711088] [<ffffffff83cfab18>] tracesys+0xe1/0xe6 [ 549.728001] ---[ end trace 73eb41728f11f87e ]--- Reported-by: Sasha Levin <levinsasha928@gmail.com> Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-03-18n_tty: Correct unthrottle-with-buffer-flush commentsPeter Hurley1-8/+5
The driver is no longer unthrottled on buffer reset, so remove comments that claim it is. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-03-18n_tty: Don't flush buffer when closing ldiscPeter Hurley1-1/+3
A buffer flush is both undesirable and unnecessary when the ldisc is closing. A buffer flush performs the following: 1. resets ldisc data fields to their initial state 2. resets tty->receive_room to indicate more data can be sent 3. schedules buffer work to receive more data 4. signals a buffer flush has happened to linked pty in packet mode Since the ldisc has been halted and the tty may soon be destructed, buffer work must not be scheduled as that work might access an invalid tty and ldisc state. Also, the ldisc read buffer is about to be freed, so that's pointless. Resetting the ldisc data fields is pointless as well since that structure is about to be freed. Resetting tty->receive_room is unnecessary, as it will be properly reset if a new ldisc is reopened. Besides, resetting the original receive_room value would be wrong since the read buffer will be gone. Since the packet mode flush is observable from userspace, this behavior has been preserved. The test jig originally authored by Ilya Zykov <ilya@ilyx.ru> and signed off by him is included below. The test jig prompts the following warnings which this patch fixes. [ 38.051111] ------------[ cut here ]------------ [ 38.052113] WARNING: at drivers/tty/n_tty.c:160 n_tty_set_room.part.6+0x8b/0xa0() [ 38.053916] Hardware name: Bochs [ 38.054819] Modules linked in: netconsole configfs bnep rfcomm bluetooth parport_pc ppdev snd_hda_intel snd_hda_codec snd_hwdep snd_pcm snd_seq_midi snd_rawmidi snd_seq_midi_event snd_seq psmouse snd_timer serio_raw mac_hid snd_seq_device snd microcode lp parport virtio_balloon soundcore i2c_piix4 snd_page_alloc floppy 8139too 8139cp [ 38.059704] Pid: 1564, comm: pty_kill Tainted: G W 3.7.0-next-20121130+ttydebug-xeon #20121130+ttydebug [ 38.061578] Call Trace: [ 38.062491] [<ffffffff81058b4f>] warn_slowpath_common+0x7f/0xc0 [ 38.063448] [<ffffffff81058baa>] warn_slowpath_null+0x1a/0x20 [ 38.064439] [<ffffffff8142dc2b>] n_tty_set_room.part.6+0x8b/0xa0 [ 38.065381] [<ffffffff8142dc82>] n_tty_set_room+0x42/0x80 [ 38.066323] [<ffffffff8142e6f2>] reset_buffer_flags+0x102/0x160 [ 38.077508] [<ffffffff8142e76d>] n_tty_flush_buffer+0x1d/0x90 [ 38.078782] [<ffffffff81046569>] ? default_spin_lock_flags+0x9/0x10 [ 38.079734] [<ffffffff8142e804>] n_tty_close+0x24/0x60 [ 38.080730] [<ffffffff81431b61>] tty_ldisc_close.isra.2+0x41/0x60 [ 38.081680] [<ffffffff81431bbb>] tty_ldisc_kill+0x3b/0x80 [ 38.082618] [<ffffffff81432a07>] tty_ldisc_release+0x77/0xe0 [ 38.083549] [<ffffffff8142b781>] tty_release+0x451/0x4d0 [ 38.084525] [<ffffffff811950be>] __fput+0xae/0x230 [ 38.085472] [<ffffffff8119524e>] ____fput+0xe/0x10 [ 38.086401] [<ffffffff8107aa88>] task_work_run+0xc8/0xf0 [ 38.087334] [<ffffffff8105ea56>] do_exit+0x196/0x4b0 [ 38.088304] [<ffffffff8106c77b>] ? __dequeue_signal+0x6b/0xb0 [ 38.089240] [<ffffffff8105ef34>] do_group_exit+0x44/0xa0 [ 38.090182] [<ffffffff8106f43d>] get_signal_to_deliver+0x20d/0x4e0 [ 38.091125] [<ffffffff81016979>] do_signal+0x29/0x130 [ 38.092096] [<ffffffff81431a9e>] ? tty_ldisc_deref+0xe/0x10 [ 38.093030] [<ffffffff8142a317>] ? tty_write+0xb7/0xf0 [ 38.093976] [<ffffffff81193f53>] ? vfs_write+0xb3/0x180 [ 38.094904] [<ffffffff81016b20>] do_notify_resume+0x80/0xc0 [ 38.095830] [<ffffffff81700492>] int_signal+0x12/0x17 [ 38.096788] ---[ end trace 5f6f7a9651cd999b ]--- [ 2730.570602] ------------[ cut here ]------------ [ 2730.572130] WARNING: at drivers/tty/n_tty.c:160 n_tty_set_room+0x107/0x140() [ 2730.574904] scheduling buffer work for halted ldisc [ 2730.578303] Pid: 9691, comm: trinity-child15 Tainted: G W 3.7.0-rc8-next-20121205-sasha-00023-g59f0d85 #207 [ 2730.588694] Call Trace: [ 2730.590486] [<ffffffff81c41d77>] ? n_tty_set_room+0x107/0x140 [ 2730.592559] [<ffffffff8110c827>] warn_slowpath_common+0x87/0xb0 [ 2730.595317] [<ffffffff8110c8b1>] warn_slowpath_fmt+0x41/0x50 [ 2730.599186] [<ffffffff81c41d77>] n_tty_set_room+0x107/0x140 [ 2730.603141] [<ffffffff81c42fe7>] reset_buffer_flags+0x137/0x150 [ 2730.607166] [<ffffffff81c43018>] n_tty_flush_buffer+0x18/0x90 [ 2730.610123] [<ffffffff81c430af>] n_tty_close+0x1f/0x60 [ 2730.612068] [<ffffffff81c461f2>] tty_ldisc_close.isra.4+0x52/0x60 [ 2730.614078] [<ffffffff81c462ab>] tty_ldisc_reinit+0x3b/0x70 [ 2730.615891] [<ffffffff81c46db2>] tty_ldisc_hangup+0x102/0x1e0 [ 2730.617780] [<ffffffff81c3e537>] __tty_hangup+0x137/0x440 [ 2730.619547] [<ffffffff81c3e869>] tty_vhangup+0x9/0x10 [ 2730.621266] [<ffffffff81c48f1c>] pty_close+0x14c/0x160 [ 2730.622952] [<ffffffff81c3fd45>] tty_release+0xd5/0x490 [ 2730.624674] [<ffffffff8127fbe2>] __fput+0x122/0x250 [ 2730.626195] [<ffffffff8127fd19>] ____fput+0x9/0x10 [ 2730.627758] [<ffffffff81134602>] task_work_run+0xb2/0xf0 [ 2730.629491] [<ffffffff811139ad>] do_exit+0x36d/0x580 [ 2730.631159] [<ffffffff81113c8a>] do_group_exit+0x8a/0xc0 [ 2730.632819] [<ffffffff81127351>] get_signal_to_deliver+0x501/0x5b0 [ 2730.634758] [<ffffffff8106de34>] do_signal+0x24/0x100 [ 2730.636412] [<ffffffff81204865>] ? user_exit+0xa5/0xd0 [ 2730.638078] [<ffffffff81183cd8>] ? trace_hardirqs_on_caller+0x118/0x140 [ 2730.640279] [<ffffffff81183d0d>] ? trace_hardirqs_on+0xd/0x10 [ 2730.642164] [<ffffffff8106df78>] do_notify_resume+0x48/0xa0 [ 2730.643966] [<ffffffff83cdff6a>] int_signal+0x12/0x17 [ 2730.645672] ---[ end trace a40d53149c07fce0 ]--- /* * pty_thrash.c * * Based on original test jig by Ilya Zykov <ilya@ilyx.ru> * * Signed-off-by: Peter Hurley <peter@hurleysoftware.com> * Signed-off-by: Ilya Zykov <ilya@ilyx.ru> */ static int fd; static void error_exit(char *f, ...) { va_list va; va_start(va, f); vprintf(f, va); printf(": %s\n", strerror(errno)); va_end(va); if (fd >= 0) close(fd); exit(EXIT_FAILURE); } int main(int argc, char *argv[]) { int parent; char pts_name[24]; int ptn, unlock; while (1) { fd = open("/dev/ptmx", O_RDWR); if (fd < 0) error_exit("opening pty master"); unlock = 0; if (ioctl(fd, TIOCSPTLCK, &unlock) < 0) error_exit("unlocking pty pair"); if (ioctl(fd, TIOCGPTN, &ptn) < 0) error_exit("getting pty #"); snprintf(pts_name, sizeof(pts_name), "/dev/pts/%d", ptn); child_id = fork(); if (child_id == -1) error_exit("forking child"); if (parent) { int err, id, status; char buf[128]; int n; n = read(fd, buf, sizeof(buf)); if (n < 0) error_exit("master reading"); printf("%.*s\n", n-1, buf); close(fd); err = kill(child_id, SIGKILL); if (err < 0) error_exit("killing child"); id = waitpid(child_id, &status, 0); if (id < 0 || id != child_id) error_exit("waiting for child"); } else { /* Child */ close(fd); printf("Test cycle on slave pty %s\n", pts_name); fd = open(pts_name, O_RDWR); if (fd < 0) error_exit("opening pty slave"); while (1) { char pattern[] = "test\n"; if (write(fd, pattern, strlen(pattern)) < 0) error_exit("slave writing"); } } } /* never gets here */ return 0; } Reported-by: Sasha Levin <levinsasha928@gmail.com> Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-03-18n_tty: Factor packet mode status change for reusePeter Hurley1-10/+14
Factor the packet mode status change from n_tty_flush_buffer for use by follow-on patch. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-03-18tty: Add diagnostic for halted line disciplinePeter Hurley1-0/+8
Flip buffer work must not be scheduled by the line discipline after the line discipline has been halted; issue warning. Note: drivers can still schedule flip buffer work. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-03-18n_tty: Lock access to tty->pgrp for POSIX job controlPeter Hurley1-16/+18
Concurrent access to tty->pgrp must be protected with tty->ctrl_lock. Also, as noted in the comments, reading current->signal->tty is safe because either, 1) current->signal->tty is assigned by current, or 2) current->signal->tty is set to NULL. NB: for reference, tty_check_change() implements a similar POSIX check for the ioctls corresponding to tcflush(), tcdrain(), tcsetattr(), tcsetpgrp(), tcflow() and tcsendbreak(). Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-03-18n_tty: Fix unsafe driver-side signalsPeter Hurley1-20/+14
An ldisc reference is insufficient guarantee the foreground process group is not in the process of being signalled from a hangup. 1) Reads of tty->pgrp must be locked with ctrl_lock 2) The group pid must be referenced for the duration of signalling. Because the driver-side is not process-context, a pid reference must be acquired. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-03-18n_tty: Fix stuck throttled driverPeter Hurley1-11/+17
As noted in the following comment: /* FIXME: there is a tiny race here if the receive room check runs before the other work executes and empties the buffer (upping the receiving room and unthrottling. We then throttle and get stuck. This has been observed and traced down by Vincent Pillet/ We need to address this when we sort out out the rx path locking */ Use new safe throttle/unthrottle functions to re-evaluate conditions if interrupted by the complement flow control function. Reported-by: Vincent Pillet <vincentx.pillet@intel.com> Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-03-18n_tty: Inline check_unthrottle() at lone call sitePeter Hurley1-16/+2
2-line function check_unthrottle() is now only called from n_tty_read(); merge into caller. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-02-13pps: Move timestamp read into PPS code properGeorge Spelvin1-1/+2
The PPS (Pulse-Per-Second) line discipline has developed a number of unhealthy attachments to core tty data and functions, ultimately leading to its breakage. The previous patches fixed the crashing. This one reduces coupling further by eliminating the timestamp parameter from the dcd_change ldisc method. This reduces header file linkage and makes the extension more generic, and the timestamp read is delayed only slightly, from just before the ldisc->ops->dcd_change method call to just after. Fix attendant build breakage in drivers/tty/n_tty.c drivers/tty/tty_buffer.c drivers/staging/speakup/selection.c drivers/staging/dgrp/dgrp_*.c Cc: William Hubbs <w.d.hubbs@gmail.com> Cc: Chris Brannon <chris@the-brannons.com> Cc: Kirk Reiser <kirk@braille.uwo.ca> Cc: Samuel Thibault <samuel.thibault@ens-lyon.org> Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: George Spelvin <linux@horizon.com> Acked-by: Rodolfo Giometti <giometti@enneenne.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-02-04tty: Use raw spin lock to protect the TTY read sectionIvo Sieben1-28/+28
The "normal" spin lock that guards the N_TTY line discipline read section is replaced by a raw spin lock. On a PREEMP_RT system this prevents unwanted scheduling overhead when data is read at the same time as data is being received: while RX IRQ threaded handling is busy a TTY read call is performed from a RT priority > threaded IRQ priority. The read call tries to take the read section spin lock (held by the threaded IRQ) which blocks and causes a context switch to/from the threaded IRQ handler until the spin lock is unlocked. Signed-off-by: Ivo Sieben <meltedpianoman@gmail.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-01-29Revert "n_tty: Unthrottle tty when flushing read buffer"Greg Kroah-Hartman1-2/+0
This reverts commit 58f82be334ede87aa6ff6fa1afdb05552be907be. This was fixed by a previous patch already. Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-01-25n_tty: Unthrottle tty when flushing read bufferKarthik Manamcheri1-0/+2
When the tty input buffer is full and thereby throttled, flushing/resetting the read buffer should unthrottle to allow more data to be received. Signed-off-by: Karthik Manamcheri <Karthik.Manamcheri@ni.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-10-25tty: add missing newlines to WARN_RATELIMITSasha Levin1-1/+1
WARN_RATELIMIT() expects the warning to end with a newline if one is needed. Not doing so results in odd looking warnings such as: [ 1339.454272] tty is NULLPid: 7147, comm: kworker/4:0 Tainted: G W 3.7.0-rc2-next-20121025-sasha-00001-g673f98e-dirty #75 Signed-off-by: Sasha Levin <sasha.levin@oracle.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-10-22TTY: move tty buffers to tty_portJiri Slaby1-2/+5
So this is it. The big step why we did all the work over the past kernel releases. Now everything is prepared, so nothing protects us from doing that big step. | | \ \ nnnn/^l | | | | \ / / | | | '-,.__ => \/ ,-` => | '-,.__ | O __.´´) ( .` | O __.´´) ~~~ ~~ `` ~~~ ~~ The buffers are now in the tty_port structure and we can start teaching the buffer helpers (insert char/string, flip etc.) to use tty_port instead of tty_struct all around. Signed-off-by: Jiri Slaby <jslaby@suse.cz> Acked-by: Alan Cox <alan@linux.intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-10-22TTY: n_tty, propagate n_tty_dataJiri Slaby1-93/+78
In some funtions we need only n_tty_data, so pass it down directly in case tty is not needed there. Signed-off-by: Jiri Slaby <jslaby@suse.cz> Acked-by: Alan Cox <alan@linux.intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-10-22TTY: move ldisc data from tty_struct: locksJiri Slaby1-51/+72
atomic_write_lock is not n_tty specific, so move it up in the tty_struct. And since these are the last ones to move, remove also the comment saying there are some ldisc' members. There are none now. Signed-off-by: Jiri Slaby <jslaby@suse.cz> Acked-by: Alan Cox <alan@linux.intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-10-22TTY: move ldisc data from tty_struct: read_* and echo_* and canon_* stuffJiri Slaby1-123/+137
All the ring-buffers... Signed-off-by: Jiri Slaby <jslaby@suse.cz> Acked-by: Alan Cox <alan@linux.intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-10-22TTY: move ldisc data from tty_struct: bitmapsJiri Slaby1-24/+28
Here we move bitmaps and use DECLARE_BITMAP to declare them in the new structure. And instead of memset, we use bitmap_zero as it is more appropriate. Signed-off-by: Jiri Slaby <jslaby@suse.cz> Acked-by: Alan Cox <alan@linux.intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-10-22TTY: move ldisc data from tty_struct: simple membersJiri Slaby1-67/+93
Here we start moving all the n_tty related bits from tty_struct to the newly defined n_tty_data struct in n_tty proper. In this patch primitive members and bits are moved. The rest will be done per-partes in the next patches. Signed-off-by: Jiri Slaby <jslaby@suse.cz> Acked-by: Alan Cox <alan@linux.intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-10-22TTY: n_tty, add ldisc data to n_ttyJiri Slaby1-1/+18
All n_tty related members from tty_struct will be moved here. Signed-off-by: Jiri Slaby <jslaby@suse.cz> Acked-by: Alan Cox <alan@linux.intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-10-22TTY: audit, stop accessing tty->icountJiri Slaby1-2/+3
This is a private member of n_tty. Stop accessing it. Instead, take is as an argument. This is needed to allow clean switch of the private members to a separate private structure of n_tty. Signed-off-by: Jiri Slaby <jslaby@suse.cz> Acked-by: Alan Cox <alan@linux.intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-10-22TTY: n_tty, remove bogus checksJiri Slaby1-12/+0
* BUG_ON(!tty) in n_tty_set_termios -- it cannot be called with tty == NULL. It is called from two call sites. First, from n_tty_open where we have a valid tty. Second, as ld->ops->set_termios from tty_set_termios. But there we have a valid tty too. * if (!tty) in n_tty_open -- why would the TTY layer call ldisc's open with an invalid TTY? No it indeed does not. All call sites have a tty and dereference that. * BUG_ON(!tty->read_buf) in n_tty_read -- this used to be a valid check. The ldisc handling was broken some time ago when I added the check to ensure everything is OK. It still can catch the case, but no later than we move the buffer to ldisc data. Then there will be no read_buf in tty_struct, i.e. nothing to check for. * if (!tty->read_buf) in n_tty_receive_buf -- this should never happen. All callers of ldisc->ops->receive_ops should hold a reference to an ldisc and close (which frees read_buf) cannot be called until the reference is dropped. * if (WARN_ON(!tty->read_buf)) in n_tty_read -- the same as in the previous case. Signed-off-by: Jiri Slaby <jslaby@suse.cz> Acked-by: Alan Cox <alan@linux.intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-10-22TTY: n_tty, simplify read_buf+echo_buf allocationJiri Slaby1-18/+13
ldisc->open and close are called only once and cannot cross. So the tests in open and close are superfluous. Remove them. (But leave sets to NULL to ensure there is not a bug somewhere.) And when the tests are gone, handle properly failures in open. We leaked read_buf if allocation of echo_buf failed before. Now this is not the case anymore. Signed-off-by: Jiri Slaby <jslaby@suse.cz> Acked-by: Alan Cox <alan@linux.intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-08-16Remove BUG_ON from n_tty_read()Stanislav Kozina1-1/+2
Change the BUG_ON to WARN_ON and return in case of tty->read_buf==NULL. We want to track a couple of long standing reports of this but at the same time we can avoid killing the box. Signed-off-by: Stanislav Kozina <skozina@redhat.com> Signed-off-by: Alan Cox <alan@linux.intel.com> Cc: Horses <stable@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-08-10n_tty: Don't lose characters when PARMRK is enabledJaeden Amero1-2/+10
When PARMRK is set and large transfers of characters that will get marked are being received, n_tty could drop data silently (i.e. without reporting any error to the client). This is because characters have the potential to take up to three bytes in the line discipline (when they get marked with parity or framing errors), but the amount of free space reported to tty_buffer flush_to_ldisc (via tty->receive_room) is based on the pre-marked data size. With this patch, the n_tty layer will no longer assume that each byte will only take up one byte in the line discipline. Instead, it will make an overly conservative estimate that each byte will take up three bytes in the line discipline when PARMRK is set. Signed-off-by: Jaeden Amero <jaeden.amero@ni.com> Acked-by: Alan Cox <alan@linux.intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-08-10tty: Fix possible race in n_tty_read()Stanislav Kozina1-1/+5
Fix possible panic caused by unlocked access to tty->read_cnt in while-loop condition in n_tty_read(). Signed-off-by: Stanislav Kozina <skozina@redhat.com> Signed-off-by: Alan Cox <alan@linux.intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-07-16tty: move the termios object into the ttyAlan Cox1-1/+1
This will let us sort out a whole pile of tty related races. The alternative would be to keep points and refcount the termios objects. However 1. They are tiny anyway 2. Many devices don't use the stored copies 3. We can remove a pty special case Signed-off-by: Alan Cox <alan@linux.intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-06-26tty: note race we need to fixAlan Cox1-0/+6
This was identified by Vincent Pillet with a high speed interface that uses low latency mode. In the low latency case we have a tiny race but it can be hit. Signed-off-by: Alan Cox <alan@linux.intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-04-29TTY: n_tty, do not dereference user bufferJiri Slaby1-4/+5
copy_from_read_buf currently copies data to a user buffer and then checks if the data is single EOF. But it checks it by accessing the user buffer. First, the buffer may be changed by other threads of the user program already. Second, it accesses the buffer without any checks. It might be write-only for example. Fix this by inspecting contents of the tty (kernel) buffer instead. Note that "n == 1" is necessary, but not sufficient. But we check later that there is nothing left by "!tty->read_cnt" condition. There is still an issue with the current code that EOF being wrapped to the start of the circular buffer will result in an inappropriate losing of the EOF character. But this is not intended to be fixed by this patch. Signed-off-by: Jiri Slaby <jslaby@suse.cz> Reported-by: Emil Goode <emilgoode@gmail.com> Cc: Howard Chu <hyc@symas.com> Cc: Alan Cox <alan@lxorguk.ukuu.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-03-28Remove all #inclusions of asm/system.hDavid Howells1-1/+0
Remove all #inclusions of asm/system.h preparatory to splitting and killing it. Performed with the following command: perl -p -i -e 's!^#\s*include\s*<asm/system[.]h>.*\n!!' `grep -Irl '^#\s*include\s*<asm/system[.]h>' *` Signed-off-by: David Howells <dhowells@redhat.com>
2011-12-09drivers/tty: Remove unneeded spacesThorsten Wißmann1-4/+4
coding style fixes in n_tty.c Signed-off-by: Maximilian Krüger <maxfragg@gmail.com> Signed-off-by: Thorsten Wißmann <re06huxa@cip.cs.fau.de> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2011-07-25Merge branch 'tty-next' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty-2.6Linus Torvalds1-1/+1
* 'tty-next' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty-2.6: (26 commits) amba pl011: workaround for uart registers lockup n_gsm: fix the wrong FCS handling pch_uart: add missing comment about OKI ML7223 pch_uart: Add MSI support tty: fix "IRQ45: nobody cared" PTI feature to allow user to name and mark masterchannel request. 0 for o PTI Makefile bug. tty: serial: samsung.c remove legacy PM code. SERIAL: SC26xx: Fix link error. serial: mrst_max3110: initialize waitqueue earlier mrst_max3110: Change max missing message priority. tty: s5pv210: Add delay loop on fifo reset function for UART tty/serial: Fix XSCALE serial ports, e.g. ce4100 serial: bfin_5xx: fix off-by-one with resource size drivers/tty: use printk_ratelimited() instead of printk_ratelimit() tty: n_gsm: Added refcount usage to gsm_mux and gsm_dlci structs tty: n_gsm: Add raw-ip support tty: n_gsm: expose gsmtty device nodes at ldisc open time pch_phub: Fix register miss-setting issue serial: 8250, increase PASS_LIMIT ...
2011-07-01tty: fix "IRQ45: nobody cared"Andrew McGregor1-1/+1
Unthrottling the TTY during close ends up enabling interrupts on a device not on the active list, which will never have the interrupts cleared. Doctor, it hurts when I do this. >>> On 6/2/2011 at 01:56 AM, in message <20110601145608.3e586e16@bob.linux.org.uk>, Alan Cox <alan@linux.intel.com> wrote: > On Wed, 01 Jun 2011 10:34:07 +1200 > "andrew mcgregor" <andrew.mcgregor@alliedtelesis.co.nz> wrote: > > The LKML message > > http://kerneltrap.org/mailarchive/linux-kernel/2010/2/25/4541847 from > > February doesn't seem to have been resolved since. We struck the > > issue, and the patch below (against 2.6.32) fixes it. Should I > > supply a patch against 3.0.0rc? > > I think that would be sensible. I don't actually see how you hit it as > the IRQ ought to be masked by then but it's certainly wrong for n_tty > to be calling into check_unthrottle at that point. > > So yes please send a patch with a suitable Signed-off-by: line to > linux-serial and cc GregKH <greg@kroah.com> as well. > > Alan Signed-off-by: Andrew McGregor <andrew.mcgregor@alliedtelesis.co.nz> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2011-06-07TTY: ntty, add one more sanity checkJiri Slaby1-0/+1
With the previous patch, we fixed another bug where read_buf was freed while we still was in n_tty_read. We currently check whether read_buf is NULL at the start of the function. Add one more check after we wake up from waiting for input. Signed-off-by: Jiri Slaby <jslaby@suse.cz> Cc: Alan Cox <alan@lxorguk.ukuu.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2011-06-04Revert "tty: make receive_buf() return the amout of bytes received"Linus Torvalds1-14/+47
This reverts commit b1c43f82c5aa265442f82dba31ce985ebb7aa71c. It was broken in so many ways, and results in random odd pty issues. It re-introduced the buggy schedule_work() in flush_to_ldisc() that can cause endless work-loops (see commit a5660b41af6a: "tty: fix endless work loop when the buffer fills up"). It also used an "unsigned int" return value fo the ->receive_buf() function, but then made multiple functions return a negative error code, and didn't actually check for the error in the caller. And it didn't actually work at all. BenH bisected down odd tty behavior to it: "It looks like the patch is causing some major malfunctions of the X server for me, possibly related to PTYs. For example, cat'ing a large file in a gnome terminal hangs the kernel for -minutes- in a loop of what looks like flush_to_ldisc/workqueue code, (some ftrace data in the quoted bits further down). ... Some more data: It -looks- like what happens is that the flush_to_ldisc work queue entry constantly re-queues itself (because the PTY is full ?) and the workqueue thread will basically loop forver calling it without ever scheduling, thus starving the consumer process that could have emptied the PTY." which is pretty much exactly the problem we fixed in a5660b41af6a. Milton Miller pointed out the 'unsigned int' issue. Reported-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Reported-by: Milton Miller <miltonm@bga.com> Cc: Stefan Bigler <stefan.bigler@keymile.com> Cc: Toby Gray <toby.gray@realvnc.com> Cc: Felipe Balbi <balbi@ti.com> Cc: Greg Kroah-Hartman <gregkh@suse.de> Cc: Alan Cox <alan@lxorguk.ukuu.org.uk> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-04-22tty: make receive_buf() return the amout of bytes receivedFelipe Balbi1-47/+14
it makes it simpler to keep track of the amount of bytes received and simplifies how flush_to_ldisc counts the remaining bytes. It also fixes a bug of lost bytes on n_tty when flushing too many bytes via the USB serial gadget driver. Tested-by: Stefan Bigler <stefan.bigler@keymile.com> Tested-by: Toby Gray <toby.gray@realvnc.com> Signed-off-by: Felipe Balbi <balbi@ti.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2011-04-04tty: fix endless work loop when the buffer fills upLinus Torvalds1-0/+6
Commit f23eb2b2b285 ('tty: stop using "delayed_work" in the tty layer') ended up causing hung machines on UP with no preemption, because the work routine to flip the buffer data to the ldisc would endlessly re-arm itself if the destination buffer had filled up. With the delayed work, that only caused a timer-driving polling of the tty state every timer tick, but without the delay we just ended up with basically a busy loop instead. Stop the insane polling, and instead make the code that opens up the receive room re-schedule the buffer flip work. That's what we should have been doing anyway. This same "poll for tty room" issue is almost certainly also the cause of excessive kworker activity when idle reported by Dave Jones, who also reported "flush_to_ldisc executing 2500 times a second" back in Nov 2010: http://lkml.org/lkml/2010/11/30/592 which is that silly flushing done every timer tick. Wasting both power and CPU for no good reason. Reported-and-tested-by: Alexander Beregalov <a.beregalov@gmail.com> Reported-and-tested-by: Sitsofe Wheeler <sitsofe@yahoo.com> Cc: Greg KH <gregkh@suse.de> Cc: Alan Cox <alan@lxorguk.ukuu.org.uk> Cc: Dave Jones <davej@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-11-05TTY: create drivers/tty and move the tty core files thereGreg Kroah-Hartman1-0/+2121
The tty code should be in its own subdirectory and not in the char driver with all of the cruft that is currently there. Based on work done by Arnd Bergmann <arnd@arndb.de> Acked-by: Arnd Bergmann <arnd@arndb.de> Cc: Jiri Slaby <jslaby@suse.cz> Cc: Alan Cox <alan@lxorguk.ukuu.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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