1. 18 Mar, 2013 40 commits
    • Peter Hurley's avatar
      tty: Separate release semantics of ldisc reference · ebc9baed
      Peter Hurley authored
      tty_ldisc_ref()/tty_ldisc_unref() have usage semantics
      equivalent to down_read_trylock()/up_read(). Only
      callers of tty_ldisc_put() are performing the additional
      operations necessary for proper ldisc teardown, and then only
      after ensuring no outstanding 'read lock' remains.
      
      Thus, tty_ldisc_unref() should never be the last reference;
      WARN if it is. Conversely, tty_ldisc_put() should never be
      destructing if the use count != 1.
      Signed-off-by: default avatarPeter Hurley <peter@hurleysoftware.com>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      ebc9baed
    • Peter Hurley's avatar
      tty: Don't protect atomic operation with mutex · 8842dda2
      Peter Hurley authored
      test_bit() is already atomic; drop mutex lock/unlock.
      Signed-off-by: default avatarPeter Hurley <peter@hurleysoftware.com>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      8842dda2
    • Peter Hurley's avatar
      tty: Add ldisc hangup debug messages · fc575ee6
      Peter Hurley authored
      Expected typical debug log:
      [  582.721965] tty_open: opening pts3...
      [  582.721970] tty_open: opening pts3...
      [  582.721977] tty_release: pts3 (tty count=3)...
      [  582.721980] tty_release: ptm3 (tty count=1)...
      [  582.722015] pts3 vhangup...
      [  582.722020] tty_ldisc_hangup: pts3: closing ldisc: ffff88007a920540
      [  582.724128] tty_release: pts3 (tty count=2)...
      [  582.724217] tty_ldisc_hangup: pts3: re-opened ldisc: ffff88007a920580
      [  582.724221] tty_release: ptm3: final close
      [  582.724234] tty_ldisc_release: ptm3: closing ldisc: ffff88007a920a80
      [  582.724238] tty_ldisc_release: ptm3: ldisc closed
      [  582.724241] tty_release: ptm3: freeing structure...
      [  582.724741] tty_open: opening pts3...
      Signed-off-by: default avatarPeter Hurley <peter@hurleysoftware.com>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      fc575ee6
    • Peter Hurley's avatar
      tty: Bracket ldisc release with TTY_DEBUG_HANGUP messages · 96433d10
      Peter Hurley authored
      Expected typical log output:
      [    2.437211] tty_open: opening pts1...
      [    2.443376] tty_open: opening pts5...
      [    2.447830] tty_release: ptm0 (tty count=1)...
      [    2.447849] pts0 vhangup...
      [    2.447865] tty_release: ptm0: final close
      [    2.447876] tty_release: ptm0: freeing structure...
      [    2.451634] tty_release: tty1 (tty count=1)...
      [    2.451638] tty_release: tty1: final close
      [    2.451654] tty_release: tty1: freeing structure...
      [    2.452505] tty_release: pts5 (tty count=2)...
      [    2.453029] tty_open: opening pts0...
      Signed-off-by: default avatarPeter Hurley <peter@hurleysoftware.com>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      96433d10
    • Peter Hurley's avatar
      tty: Fix 'deferred reopen' ldisc comment · c8785241
      Peter Hurley authored
      This comment is a victim of code migration from
      "tty: Fix the ldisc hangup race"; re-parent it.
      Signed-off-by: default avatarPeter Hurley <peter@hurleysoftware.com>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      c8785241
    • Peter Hurley's avatar
      tty: Make core responsible for synchronizing its work · a2965b7b
      Peter Hurley authored
      The tty core relies on the ldisc layer for synchronizing destruction
      of the tty. Instead, the final tty release must wait for any pending tty
      work to complete prior to tty destruction.
      Signed-off-by: default avatarPeter Hurley <peter@hurleysoftware.com>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      a2965b7b
    • Peter Hurley's avatar
      tty: Complete ownership transfer of flip buffers · 4f98d467
      Peter Hurley authored
      Waiting for buffer work to complete is not required for safely
      performing changes to the line discipline, once the line discipline
      is halted. The buffer work routine, flush_to_ldisc(), will be
      unable to acquire an ldisc ref and all existing references were
      waited until released (so it can't already have one).
      
      Ensure running buffer work which may reference the soon-to-be-gone
      tty completes and any buffer work running after this point retrieves
      a NULL tty.
      
      Also, ensure all buffer work is cancelled on port destruction.
      Signed-off-by: default avatarPeter Hurley <peter@hurleysoftware.com>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      4f98d467
    • Peter Hurley's avatar
      tty: Don't reenable already enabled ldisc · d9121566
      Peter Hurley authored
      tty_ldisc_hangup() guarantees the ldisc is enabled (or that there
      is no ldisc). Since __tty_hangup() was the only user, re-define
      tty_ldisc_enable() in file-scope.
      Signed-off-by: default avatarPeter Hurley <peter@hurleysoftware.com>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      d9121566
    • Peter Hurley's avatar
      n_tty: Fully initialize ldisc before restarting buffer work · b66f4fa5
      Peter Hurley authored
      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: default avatarSasha Levin <levinsasha928@gmail.com>
      Signed-off-by: default avatarPeter Hurley <peter@hurleysoftware.com>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      b66f4fa5
    • Peter Hurley's avatar
      n_tty: Correct unthrottle-with-buffer-flush comments · 25518c68
      Peter Hurley authored
      The driver is no longer unthrottled on buffer reset, so remove
      comments that claim it is.
      Signed-off-by: default avatarPeter Hurley <peter@hurleysoftware.com>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      25518c68
    • Peter Hurley's avatar
      tty: Wait for SAK work before waiting for hangup work · 977066e7
      Peter Hurley authored
      SAK work may schedule hangup work (if TTY_SOFT_SAK is defined), thus
      SAK work must be flushed before hangup work.
      Signed-off-by: default avatarPeter Hurley <peter@hurleysoftware.com>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      977066e7
    • Peter Hurley's avatar
      tty: Halt both ldiscs concurrently · f4cf7a38
      Peter Hurley authored
      The pty driver does not obtain an ldisc reference to the linked
      tty when writing. When the ldiscs are sequentially halted, it
      is possible for one ldisc to be halted, and before the second
      ldisc can be halted, a concurrent write schedules buffer work on
      the first ldisc. This can lead to an access-after-free error when
      the scheduled buffer work starts on the closed ldisc.
      
      Prevent subsequent use after halt by performing each stage
      of the halt on both ttys.
      Signed-off-by: default avatarPeter Hurley <peter@hurleysoftware.com>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      f4cf7a38
    • Peter Hurley's avatar
      tty: Strengthen no-subsequent-use guarantee of tty_ldisc_halt() · cf528476
      Peter Hurley authored
      In preparation for destructing and freeing the tty, the line discipline
      must first be brought to an inactive state before it can be destructed.
      This line discipline shutdown must:
       - disallow new users of the ldisc
       - wait for existing ldisc users to finish
       - only then, cancel/flush their pending/running work
      
      Factor tty_ldisc_wait_idle() from tty_set_ldisc() and tty_ldisc_kill()
      to ensure this shutdown order.
      
      Failure to provide this guarantee can result in scheduled work
      running after the tty has already been freed, as indicated in the
      following log message:
      
      [   88.331234] WARNING: at drivers/tty/tty_buffer.c:435 flush_to_ldisc+0x194/0x1d0()
      [   88.334505] Hardware name: Bochs
      [   88.335618] tty is bad=-1
      [   88.335703] Modules linked in: netconsole configfs bnep rfcomm bluetooth ......
      [   88.345272] Pid: 39, comm: kworker/1:1 Tainted: G        W    3.7.0-next-20121129+ttydebug-xeon #20121129+ttydebug
      [   88.347736] Call Trace:
      [   88.349024]  [<ffffffff81058aff>] warn_slowpath_common+0x7f/0xc0
      [   88.350383]  [<ffffffff81058bf6>] warn_slowpath_fmt+0x46/0x50
      [   88.351745]  [<ffffffff81432bd4>] flush_to_ldisc+0x194/0x1d0
      [   88.353047]  [<ffffffff816f7fe1>] ? _raw_spin_unlock_irq+0x21/0x50
      [   88.354190]  [<ffffffff8108a809>] ? finish_task_switch+0x49/0xe0
      [   88.355436]  [<ffffffff81077ad1>] process_one_work+0x121/0x490
      [   88.357674]  [<ffffffff81432a40>] ? __tty_buffer_flush+0x90/0x90
      [   88.358954]  [<ffffffff81078c84>] worker_thread+0x164/0x3e0
      [   88.360247]  [<ffffffff81078b20>] ? manage_workers+0x120/0x120
      [   88.361282]  [<ffffffff8107e230>] kthread+0xc0/0xd0
      [   88.362284]  [<ffffffff816f0000>] ? cmos_do_probe+0x2eb/0x3bf
      [   88.363391]  [<ffffffff8107e170>] ? flush_kthread_worker+0xb0/0xb0
      [   88.364797]  [<ffffffff816fff6c>] ret_from_fork+0x7c/0xb0
      [   88.366087]  [<ffffffff8107e170>] ? flush_kthread_worker+0xb0/0xb0
      [   88.367266] ---[ end trace 453a7c9f38fbfec0 ]---
      Signed-off-by: default avatarPeter Hurley <peter@hurleysoftware.com>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      cf528476
    • Peter Hurley's avatar
      tty: Relocate tty_ldisc_halt() to avoid forward declaration · 11cf48ea
      Peter Hurley authored
      tty_ldisc_halt() will use the file-scoped function, tty_ldisc_wait_idle(),
      in the following patch.
      Signed-off-by: default avatarPeter Hurley <peter@hurleysoftware.com>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      11cf48ea
    • Peter Hurley's avatar
      tty: Fix ldisc halt sequence on hangup · 76bc35e7
      Peter Hurley authored
      Flip buffer work cannot be cancelled until all outstanding ldisc
      references have been released. Convert the ldisc ref wait into
      a full ldisc halt with buffer work cancellation.
      
      Note that the legacy mutex is not held while cancelling.
      Signed-off-by: default avatarPeter Hurley <peter@hurleysoftware.com>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      76bc35e7
    • Peter Hurley's avatar
      tty: Remove unnecessary re-test of ldisc ref count · 2276ad97
      Peter Hurley authored
      Since the tty->ldisc is prevented from being changed by tty_set_ldisc()
      when a tty is being hung up, re-testing the ldisc user count is
      unnecessary -- ie, it cannot be a different ldisc and the user count
      cannot have increased (assuming the caller meets the precondition that
      TTY_LDISC flag is cleared)
      
      Removal of the 'early-out' locking optimization is necessary for
      the subsequent patch 'tty: Fix ldisc halt sequence on hangup'.
      Signed-off-by: default avatarPeter Hurley <peter@hurleysoftware.com>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      2276ad97
    • Peter Hurley's avatar
      tty: Refactor wait for ldisc refs out of tty_ldisc_hangup() · 168942c9
      Peter Hurley authored
      Refactor tty_ldisc_hangup() to extract standalone function,
      tty_ldisc_hangup_wait_idle(), to wait for ldisc references
      to be released.
      Signed-off-by: default avatarPeter Hurley <peter@hurleysoftware.com>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      168942c9
    • Peter Hurley's avatar
      n_tty: Don't flush buffer when closing ldisc · 79901317
      Peter Hurley authored
      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: default avatarSasha Levin <levinsasha928@gmail.com>
      Signed-off-by: default avatarPeter Hurley <peter@hurleysoftware.com>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      79901317
    • Peter Hurley's avatar
      n_tty: Factor packet mode status change for reuse · a30737ab
      Peter Hurley authored
      Factor the packet mode status change from n_tty_flush_buffer
      for use by follow-on patch.
      Signed-off-by: default avatarPeter Hurley <peter@hurleysoftware.com>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      a30737ab
    • Peter Hurley's avatar
      tty: Add diagnostic for halted line discipline · 21622939
      Peter Hurley authored
      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: default avatarPeter Hurley <peter@hurleysoftware.com>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      21622939
    • Lars-Peter Clausen's avatar
      tty: ifx6x60: Remove unused suspend/resume callbacks · 91debb03
      Lars-Peter Clausen authored
      The ifx6x60 driver implements both legacy suspend/resume callbacks and
      dev_pm_ops. The SPI core is going to ignore legacy suspend/resume
      callbacks if a driver implements dev_pm_ops. Since the legacy suspend/resume
      callbacks are empty in this case it is safe to just remove them.
      
      Cc: Bi Chao <chao.bi@intel.com>
      Cc: Chen Jun <jun.d.chen@intel.com>
      Signed-off-by: default avatarLars-Peter Clausen <lars@metafoo.de>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      91debb03
    • Lars-Peter Clausen's avatar
      tty: mrst_max3110: Use dev_pm_ops · c2ee91bd
      Lars-Peter Clausen authored
      Use dev_pm_ops instead of the deprecated legacy suspend/resume for the
      mrst_max3110 driver.
      
      Cc: Alan Cox <alan@linux.intel.com>
      Signed-off-by: default avatarLars-Peter Clausen <lars@metafoo.de>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      c2ee91bd
    • Lars-Peter Clausen's avatar
      tty: max310x: Use dev_pm_ops · b7df719d
      Lars-Peter Clausen authored
      Use dev_pm_ops instead of the deprecated legacy suspend/resume for the
      max310x driver.
      
      Cc: Alexander Shiyan <shc_work@mail.ru>
      Signed-off-by: default avatarLars-Peter Clausen <lars@metafoo.de>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      b7df719d
    • Lars-Peter Clausen's avatar
      tty: max3100: Use dev_pm_ops · c47ddc26
      Lars-Peter Clausen authored
      Use dev_pm_ops instead of the deprecated legacy suspend/resume for the
      max3100 driver.
      Signed-off-by: default avatarLars-Peter Clausen <lars@metafoo.de>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      c47ddc26
    • Johan Hovold's avatar
      TTY: fix close of uninitialised ports · 0b2588ca
      Johan Hovold authored
      Make sure we do not make tty-driver callbacks or wait for port to drain
      on uninitialised ports (e.g. when open failed) in
      tty_port_close_start().
      
      No callback, such as flush_buffer or wait_until_sent, needs to be made
      on a port that has never been opened. Neither does it make much sense to
      add drain delay for an uninitialised port.
      
      Currently a drain delay of up to two seconds could be added when a tty
      fails to open.
      Signed-off-by: default avatarJohan Hovold <jhovold@gmail.com>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      0b2588ca
    • Johan Hovold's avatar
      TTY: clean up port drain-delay handling · b74414f5
      Johan Hovold authored
      Move port drain-delay handling to a separate function.
      Signed-off-by: default avatarJohan Hovold <jhovold@gmail.com>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      b74414f5
    • Johan Hovold's avatar
      TTY: fix DTR not being dropped on hang up · 957dacae
      Johan Hovold authored
      Move HUPCL handling to port shutdown so that DTR is dropped also on hang
      up (tty_port_close is a noop for hung-up ports).
      
      Also do not try to drop DTR for uninitialised ports where it has never
      been raised (e.g. after a failed open).
      
      Note that this is also the current behaviour of serial-core.
      
      Nine drivers currently call tty_port_close_start directly (rather than
      through tty_port_close) and seven of them lower DTR as part of their
      close (if the port has been initialised). Fixup the remaining two
      drivers so that it continues to be lowered also on normal (non-HUP)
      close. [ Note that most of those other seven drivers did not expect DTR
      to have been dropped by tty_port_close_start in the first place. ]
      Signed-off-by: default avatarJohan Hovold <jhovold@gmail.com>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      957dacae
    • Johan Hovold's avatar
      TTY: fix DTR being raised on hang up · e584a02c
      Johan Hovold authored
      Make sure to check ASYNC_INITIALISED before raising DTR when waking up
      from blocked open in tty_port_block_til_ready.
      
      Currently DTR could get raised at hang up as a blocked process would
      raise DTR unconditionally before checking for hang up and returning.
      Signed-off-by: default avatarJohan Hovold <jhovold@gmail.com>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      e584a02c
    • Johan Hovold's avatar
      TTY: wake up processes last at hangup · 31ca020b
      Johan Hovold authored
      Move wake up of processes on blocked-open and modem-status wait queues
      to after port shutdown at hangup.
      
      This way the woken up processes can use the ASYNC_INITIALIZED flag to
      detect port shutdown.
      
      Note that this is the order currently used by serial-core.
      Signed-off-by: default avatarJohan Hovold <jhovold@gmail.com>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      31ca020b
    • Johan Hovold's avatar
      TTY: clean up port shutdown · 8bde9658
      Johan Hovold authored
      Untangle port-shutdown logic and make sure the initialised flag is
      always cleared for non-console ports.
      Signed-off-by: default avatarJohan Hovold <jhovold@gmail.com>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      8bde9658
    • Jiri Slaby's avatar
      crisv10: use counts from tty_port · b12d8dc2
      Jiri Slaby authored
      The same as flags, convert to using open/close counts from tty_port.
      Signed-off-by: default avatarJiri Slaby <jslaby@suse.cz>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      b12d8dc2
    • Jiri Slaby's avatar
      crisv10: use *_wait from tty_port · 4aeaeb0c
      Jiri Slaby authored
      The same as flags, convert to using *_wait queues from tty_port.
      Signed-off-by: default avatarJiri Slaby <jslaby@suse.cz>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      4aeaeb0c
    • Jiri Slaby's avatar
      crisv10: use close delays from tty_port · 892c7cfc
      Jiri Slaby authored
      The same as flags, convert to using close delays from tty_port.
      Signed-off-by: default avatarJiri Slaby <jslaby@suse.cz>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      892c7cfc
    • Jiri Slaby's avatar
      crisv10: remove unused members · 82c3b87b
      Jiri Slaby authored
      Well, all those are unused. They were perhaps copied from generic
      serial structure ages ago. Remove them for good.
      Signed-off-by: default avatarJiri Slaby <jslaby@suse.cz>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      82c3b87b
    • Jiri Slaby's avatar
      crisv10: stop returning info from handle_ser_rx_interrupt · 12aad550
      Jiri Slaby authored
      The return value is not used anywhere, so no need to return anything.
      Signed-off-by: default avatarJiri Slaby <jslaby@suse.cz>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      12aad550
    • Jiri Slaby's avatar
      crisv10: use flags from tty_port · b1d984cf
      Jiri Slaby authored
      First, remove STD_FLAGS as the value, or its subvalues
      (ASYNC_BOOT_AUTOCONF | ASYNC_SKIP_TEST) is not tested anywhere --
      there is no point to initialize flags to that. Second, use flags
      member from tty_port when we have it now. So that we do not waste
      space.
      Signed-off-by: default avatarJiri Slaby <jslaby@suse.cz>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      b1d984cf
    • Jiri Slaby's avatar
      TTY: cleanup tty->hw_stopped uses · ee797069
      Jiri Slaby authored
      tty->hw_stopped is set only by drivers to remember HW state. If it is
      never set to 1 in a particular driver, there is no need to check it in
      the driver at all. Remove such checks.
      Signed-off-by: default avatarJiri Slaby <jslaby@suse.cz>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      ee797069
    • Jiri Slaby's avatar
      4d29994d
    • Jiri Slaby's avatar
      TTY: serial/bfin_uart, unbreak build with KGDB enabled · e99c33b9
      Jiri Slaby authored
      There are no (and never were any) kgdb fields in uart_ops. Setting
      them produces a build error:
      drivers/tty/serial/bfin_uart.c:1054:2: error: unknown field 'kgdboc_port_startup' specified in initializer
      drivers/tty/serial/bfin_uart.c:1054:2: warning: initialization from incompatible pointer type [enabled by default]
      drivers/tty/serial/bfin_uart.c:1054:2: warning: (near initialization for 'bfin_serial_pops.ioctl') [enabled by default]
      drivers/tty/serial/bfin_uart.c:1055:2: error: unknown field 'kgdboc_port_shutdown' specified in initializer
      drivers/tty/serial/bfin_uart.c:1055:2: warning: initialization from incompatible pointer type [enabled by default]
      drivers/tty/serial/bfin_uart.c:1055:2: warning: (near initialization for 'bfin_serial_pops.poll_init') [enabled by default]
      
      Remove them.
      Signed-off-by: default avatarJiri Slaby <jslaby@suse.cz>
      Acked-by: default avatarSonic Zhang <sonic.zhang@analog.com>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      e99c33b9
    • Jiri Slaby's avatar
      TTY: add tty_port_tty_hangup helper · aa27a094
      Jiri Slaby authored
      It allows for cleaning up on a considerable amount of places. They did
      port_get, hangup, kref_put. Now the only thing needed is to call
      tty_port_tty_hangup which does exactly that. And they can also decide
      whether to consider CLOCAL or completely ignore that.
      Signed-off-by: default avatarJiri Slaby <jslaby@suse.cz>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      aa27a094