linux-stable.git/drivers/tty/pty.c, branch v3.9.2 Linux kernel stable tree tty: fix up atime/mtime mess, take three 2013-05-08T03:33:07+00:00 Linus Torvalds torvalds@linux-foundation.org 2013-05-01T14:32:21+00:00 c00bbdc6a871388bebebc7ab9ec5202c38887361 commit b0b885657b6c8ef63a46bc9299b2a7715d19acde upstream. We first tried to avoid updating atime/mtime entirely (commit b0de59b5733d: "TTY: do not update atime/mtime on read/write"), and then limited it to only update it occasionally (commit 37b7f3c76595: "TTY: fix atime/mtime regression"), but it turns out that this was both insufficient and overkill. It was insufficient because we let people attach to the shared ptmx node to see activity without even reading atime/mtime, and it was overkill because the "only once a minute" means that you can't really tell an idle person from an active one with 'w'. So this tries to fix the problem properly. It marks the shared ptmx node as un-notifiable, and it lowers the "only once a minute" to a few seconds instead - still long enough that you can't time individual keystrokes, but short enough that you can tell whether somebody is active or not. Reported-by: Simon Kirby <sim@hostway.ca> Acked-by: Jiri Slaby <jslaby@suse.cz> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit b0b885657b6c8ef63a46bc9299b2a7715d19acde upstream.

We first tried to avoid updating atime/mtime entirely (commit
b0de59b5733d: "TTY: do not update atime/mtime on read/write"), and then
limited it to only update it occasionally (commit 37b7f3c76595: "TTY:
fix atime/mtime regression"), but it turns out that this was both
insufficient and overkill.

It was insufficient because we let people attach to the shared ptmx node
to see activity without even reading atime/mtime, and it was overkill
because the "only once a minute" means that you can't really tell an
idle person from an active one with 'w'.

So this tries to fix the problem properly.  It marks the shared ptmx
node as un-notifiable, and it lowers the "only once a minute" to a few
seconds instead - still long enough that you can't time individual
keystrokes, but short enough that you can tell whether somebody is
active or not.

Reported-by: Simon Kirby <sim@hostway.ca>
Acked-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
pty: Ignore slave open count for master pty open 2013-02-04T23:40:29+00:00 Peter Hurley peter@hurleysoftware.com 2013-01-30T17:43:52+00:00 80cace72566633bb99da1f022f71d3dac3498b02 Multiple slave pty opens may be performed in parallel with the master open. Of course, all the slave opens will fail because the master pty is still locked but during this time the slave pty count will be artificially greater than 1. This is should not cause the master pty open to fail. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
Multiple slave pty opens may be performed in parallel with the
master open. Of course, all the slave opens will fail because the
master pty is still locked but during this time the slave pty
count will be artificially greater than 1. This is should not
cause the master pty open to fail.

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
pty: Ignore slave pty close() if never successfully opened 2013-02-04T23:40:28+00:00 Peter Hurley peter@hurleysoftware.com 2013-01-30T17:43:50+00:00 699390354da6c258b65bf8fa79cfd5feaede50b6 If the master and slave ptys are opened in parallel, the slave open fails because the pty is still locked. This is as designed. However, pty_close() is still called for the slave pty which sets TTY_OTHER_CLOSED in the master pty. This can cause the master open to fail as well. Use a common pattern in other tty drivers by setting TTY_IO_ERROR until the open is successful and only closing the pty if not set. Note: the master pty always closes regardless of whether the open was successful, so that proper cleanup can occur. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
If the master and slave ptys are opened in parallel, the slave open
fails because the pty is still locked. This is as designed.
However, pty_close() is still called for the slave pty which sets
TTY_OTHER_CLOSED in the master pty. This can cause the master open
to fail as well.

Use a common pattern in other tty drivers by setting TTY_IO_ERROR
until the open is successful and only closing the pty if not set.

Note: the master pty always closes regardless of whether the open
was successful, so that proper cleanup can occur.

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
pty: Fix BUG()s when ptmx_open() errors out 2013-02-04T23:40:28+00:00 Peter Hurley peter@hurleysoftware.com 2013-01-30T17:43:49+00:00 7acf6cd80b201f77371a5374a786144153629be8 If pmtx_open() fails to get a slave inode or fails the pty_open(), the tty is released as part of the error cleanup. As evidenced by the first BUG stacktrace below, pty_close() assumes that the linked pty has a valid, initialized inode* stored in driver_data. Also, as evidenced by the second BUG stacktrace below, pty_unix98_shutdown() assumes that the master pty's driver_data has been initialized. 1) Fix the invalid assumption in pty_close(). 2) Initialize driver_data immediately so proper devpts fs cleanup occurs. Fixes this BUG: [ 815.868844] BUG: unable to handle kernel NULL pointer dereference at 0000000000000028 [ 815.869018] IP: [<ffffffff81207bcc>] devpts_pty_kill+0x1c/0xa0 [ 815.869190] PGD 7c775067 PUD 79deb067 PMD 0 [ 815.869315] Oops: 0000 [#1] PREEMPT SMP [ 815.869443] Modules linked in: kvm_intel kvm snd_hda_intel snd_hda_codec snd_hwdep snd_pcm snd_seq_midi microcode snd_rawmidi psmouse serio_raw snd_seq_midi_event snd_seq snd_timer$ [ 815.870025] CPU 0 [ 815.870143] Pid: 27819, comm: stress_test_tty Tainted: G W 3.8.0-next-20130125+ttypatch-2-xeon #2 Bochs Bochs [ 815.870386] RIP: 0010:[<ffffffff81207bcc>] [<ffffffff81207bcc>] devpts_pty_kill+0x1c/0xa0 [ 815.870540] RSP: 0018:ffff88007d3e1ac8 EFLAGS: 00010282 [ 815.870661] RAX: ffff880079c20800 RBX: 0000000000000000 RCX: 0000000000000000 [ 815.870804] RDX: ffff880079c209a8 RSI: 0000000000000286 RDI: 0000000000000000 [ 815.870933] RBP: ffff88007d3e1ae8 R08: 0000000000000000 R09: 0000000000000000 [ 815.871078] R10: 0000000000000000 R11: 0000000000000001 R12: ffff88007bfb7e00 [ 815.871209] R13: 0000000000000005 R14: ffff880079c20c00 R15: ffff880079c20c00 [ 815.871343] FS: 00007f2e86206700(0000) GS:ffff88007fc00000(0000) knlGS:0000000000000000 [ 815.871495] CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b [ 815.871617] CR2: 0000000000000028 CR3: 000000007ae56000 CR4: 00000000000006f0 [ 815.871752] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 815.871902] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 [ 815.872012] Process stress_test_tty (pid: 27819, threadinfo ffff88007d3e0000, task ffff88007c874530) [ 815.872012] Stack: [ 815.872012] ffff88007bfb7e00 ffff880079c20c00 ffff88007bfb7e00 0000000000000005 [ 815.872012] ffff88007d3e1b08 ffffffff81417be7 ffff88007caa9bd8 ffff880079c20800 [ 815.872012] ffff88007d3e1bc8 ffffffff8140e5f8 0000000000000000 0000000000000000 [ 815.872012] Call Trace: [ 815.872012] [<ffffffff81417be7>] pty_close+0x157/0x170 [ 815.872012] [<ffffffff8140e5f8>] tty_release+0x138/0x580 [ 815.872012] [<ffffffff816d29f3>] ? _raw_spin_lock+0x23/0x30 [ 815.872012] [<ffffffff816d267a>] ? _raw_spin_unlock+0x1a/0x40 [ 815.872012] [<ffffffff816d0178>] ? __mutex_unlock_slowpath+0x48/0x60 [ 815.872012] [<ffffffff81417dff>] ptmx_open+0x11f/0x180 [ 815.872012] [<ffffffff8119394b>] chrdev_open+0x9b/0x1c0 [ 815.872012] [<ffffffff8118d643>] do_dentry_open+0x203/0x290 [ 815.872012] [<ffffffff811938b0>] ? cdev_put+0x30/0x30 [ 815.872012] [<ffffffff8118d705>] finish_open+0x35/0x50 [ 815.872012] [<ffffffff8119dcce>] do_last+0x6fe/0xe90 [ 815.872012] [<ffffffff8119a7af>] ? link_path_walk+0x7f/0x880 [ 815.872012] [<ffffffff810909d5>] ? cpuacct_charge+0x75/0x80 [ 815.872012] [<ffffffff8119e51c>] path_openat+0xbc/0x4e0 [ 815.872012] [<ffffffff816d0fd0>] ? __schedule+0x400/0x7f0 [ 815.872012] [<ffffffff8140e956>] ? tty_release+0x496/0x580 [ 815.872012] [<ffffffff8119ec11>] do_filp_open+0x41/0xa0 [ 815.872012] [<ffffffff816d267a>] ? _raw_spin_unlock+0x1a/0x40 [ 815.872012] [<ffffffff811abe39>] ? __alloc_fd+0xe9/0x140 [ 815.872012] [<ffffffff8118ea44>] do_sys_open+0xf4/0x1e0 [ 815.872012] [<ffffffff8118eb51>] sys_open+0x21/0x30 [ 815.872012] [<ffffffff816da499>] system_call_fastpath+0x16/0x1b [ 815.872012] Code: 0f 1f 80 00 00 00 00 45 31 e4 eb d7 0f 0b 90 0f 1f 44 00 00 55 48 89 e5 48 83 ec 20 48 89 5d e8 48 89 fb 4c 89 65 f0 4c 89 6d f8 <48> 8b 47 28 48 81 78 58 d1 1c 0$ [ 815.872012] RIP [<ffffffff81207bcc>] devpts_pty_kill+0x1c/0xa0 [ 815.872012] RSP <ffff88007d3e1ac8> [ 815.872012] CR2: 0000000000000028 [ 815.897036] ---[ end trace eadf50b7f34e47d5 ]--- Fixes this BUG also: [ 608.366836] BUG: unable to handle kernel NULL pointer dereference at 0000000000000028 [ 608.366948] IP: [<ffffffff812078d8>] devpts_kill_index+0x18/0x70 [ 608.367050] PGD 7c75b067 PUD 7b919067 PMD 0 [ 608.367135] Oops: 0000 [#1] PREEMPT SMP [ 608.367201] Modules linked in: kvm_intel kvm snd_hda_intel snd_hda_codec snd_hwdep snd_pcm snd_seq_midi snd_rawmidi snd_seq_midi_event microcode snd_seq psmouse snd_timer snd_seq_device serio_raw snd mac_hid soundcore snd_page_alloc rfcomm virtio_balloon parport_pc bnep bluetooth ppdev i2c_piix4 lp parport floppy [ 608.367617] CPU 2 [ 608.367669] Pid: 1918, comm: stress_test_tty Tainted: G W 3.8.0-next-20130125+ttypatch-2-xeon #2 Bochs Bochs [ 608.367796] RIP: 0010:[<ffffffff812078d8>] [<ffffffff812078d8>] devpts_kill_index+0x18/0x70 [ 608.367885] RSP: 0018:ffff88007ae41a88 EFLAGS: 00010286 [ 608.367951] RAX: ffffffff81417e80 RBX: ffff880036472400 RCX: 0000000180400028 [ 608.368010] RDX: ffff880036470004 RSI: 0000000000000004 RDI: 0000000000000000 [ 608.368010] RBP: ffff88007ae41a98 R08: 0000000000000000 R09: 0000000000000001 [ 608.368010] R10: ffffea0001f22e40 R11: ffffffff814151d5 R12: 0000000000000004 [ 608.368010] R13: ffff880036470000 R14: 0000000000000004 R15: ffff880036472400 [ 608.368010] FS: 00007ff7a5268700(0000) GS:ffff88007fd00000(0000) knlGS:0000000000000000 [ 608.368010] CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b [ 608.368010] CR2: 0000000000000028 CR3: 000000007a0fd000 CR4: 00000000000006e0 [ 608.368010] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 608.368010] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 [ 608.368010] Process stress_test_tty (pid: 1918, threadinfo ffff88007ae40000, task ffff88003688dc40) [ 608.368010] Stack: [ 608.368010] ffff880036472400 0000000000000001 ffff88007ae41aa8 ffffffff81417e98 [ 608.368010] ffff88007ae41ac8 ffffffff8140c42b ffff88007ac73100 ffff88007ac73100 [ 608.368010] ffff88007ae41b98 ffffffff8140ead5 ffff88007ae41b38 ffff88007ca40e40 [ 608.368010] Call Trace: [ 608.368010] [<ffffffff81417e98>] pty_unix98_shutdown+0x18/0x20 [ 608.368010] [<ffffffff8140c42b>] release_tty+0x3b/0xe0 [ 608.368010] [<ffffffff8140ead5>] __tty_release+0x575/0x5d0 [ 608.368010] [<ffffffff816d2c63>] ? _raw_spin_lock+0x23/0x30 [ 608.368010] [<ffffffff816d28ea>] ? _raw_spin_unlock+0x1a/0x40 [ 608.368010] [<ffffffff816d03e8>] ? __mutex_unlock_slowpath+0x48/0x60 [ 608.368010] [<ffffffff8140ef79>] tty_open+0x449/0x5f0 [ 608.368010] [<ffffffff8119394b>] chrdev_open+0x9b/0x1c0 [ 608.368010] [<ffffffff8118d643>] do_dentry_open+0x203/0x290 [ 608.368010] [<ffffffff811938b0>] ? cdev_put+0x30/0x30 [ 608.368010] [<ffffffff8118d705>] finish_open+0x35/0x50 [ 608.368010] [<ffffffff8119dcce>] do_last+0x6fe/0xe90 [ 608.368010] [<ffffffff8119a7af>] ? link_path_walk+0x7f/0x880 [ 608.368010] [<ffffffff8119e51c>] path_openat+0xbc/0x4e0 [ 608.368010] [<ffffffff8119ec11>] do_filp_open+0x41/0xa0 [ 608.368010] [<ffffffff816d28ea>] ? _raw_spin_unlock+0x1a/0x40 [ 608.368010] [<ffffffff811abe39>] ? __alloc_fd+0xe9/0x140 [ 608.368010] [<ffffffff8118ea44>] do_sys_open+0xf4/0x1e0 [ 608.368010] [<ffffffff816d2c63>] ? _raw_spin_lock+0x23/0x30 [ 608.368010] [<ffffffff8118eb51>] sys_open+0x21/0x30 [ 608.368010] [<ffffffff816da719>] system_call_fastpath+0x16/0x1b [ 608.368010] Code: ec 48 83 c4 10 5b 41 5c 5d c3 66 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 55 48 89 e5 48 83 ec 10 4c 89 65 f8 41 89 f4 48 89 5d f0 <48> 8b 47 28 48 81 78 58 d1 1c 00 00 74 0b 48 8b 05 4b 66 cf 00 [ 608.368010] RIP [<ffffffff812078d8>] devpts_kill_index+0x18/0x70 [ 608.368010] RSP <ffff88007ae41a88> [ 608.368010] CR2: 0000000000000028 [ 608.394153] ---[ end trace afe83b0fb5fbda93 ]--- Reported-by: Ilya Zykov <ilya@ilyx.ru> Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
If pmtx_open() fails to get a slave inode or fails the pty_open(),
the tty is released as part of the error cleanup. As evidenced by the
first BUG stacktrace below, pty_close() assumes that the linked pty has
a valid, initialized inode* stored in driver_data.

Also, as evidenced by the second BUG stacktrace below, pty_unix98_shutdown()
assumes that the master pty's driver_data has been initialized.

1) Fix the invalid assumption in pty_close().
2) Initialize driver_data immediately so proper devpts fs cleanup occurs.

Fixes this BUG:

[  815.868844] BUG: unable to handle kernel NULL pointer dereference at 0000000000000028
[  815.869018] IP: [<ffffffff81207bcc>] devpts_pty_kill+0x1c/0xa0
[  815.869190] PGD 7c775067 PUD 79deb067 PMD 0
[  815.869315] Oops: 0000 [#1] PREEMPT SMP
[  815.869443] Modules linked in: kvm_intel kvm snd_hda_intel snd_hda_codec snd_hwdep snd_pcm snd_seq_midi microcode snd_rawmidi psmouse serio_raw snd_seq_midi_event snd_seq snd_timer$
[  815.870025] CPU 0
[  815.870143] Pid: 27819, comm: stress_test_tty Tainted: G        W    3.8.0-next-20130125+ttypatch-2-xeon #2 Bochs Bochs
[  815.870386] RIP: 0010:[<ffffffff81207bcc>]  [<ffffffff81207bcc>] devpts_pty_kill+0x1c/0xa0
[  815.870540] RSP: 0018:ffff88007d3e1ac8  EFLAGS: 00010282
[  815.870661] RAX: ffff880079c20800 RBX: 0000000000000000 RCX: 0000000000000000
[  815.870804] RDX: ffff880079c209a8 RSI: 0000000000000286 RDI: 0000000000000000
[  815.870933] RBP: ffff88007d3e1ae8 R08: 0000000000000000 R09: 0000000000000000
[  815.871078] R10: 0000000000000000 R11: 0000000000000001 R12: ffff88007bfb7e00
[  815.871209] R13: 0000000000000005 R14: ffff880079c20c00 R15: ffff880079c20c00
[  815.871343] FS:  00007f2e86206700(0000) GS:ffff88007fc00000(0000) knlGS:0000000000000000
[  815.871495] CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
[  815.871617] CR2: 0000000000000028 CR3: 000000007ae56000 CR4: 00000000000006f0
[  815.871752] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[  815.871902] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
[  815.872012] Process stress_test_tty (pid: 27819, threadinfo ffff88007d3e0000, task ffff88007c874530)
[  815.872012] Stack:
[  815.872012]  ffff88007bfb7e00 ffff880079c20c00 ffff88007bfb7e00 0000000000000005
[  815.872012]  ffff88007d3e1b08 ffffffff81417be7 ffff88007caa9bd8 ffff880079c20800
[  815.872012]  ffff88007d3e1bc8 ffffffff8140e5f8 0000000000000000 0000000000000000
[  815.872012] Call Trace:
[  815.872012]  [<ffffffff81417be7>] pty_close+0x157/0x170
[  815.872012]  [<ffffffff8140e5f8>] tty_release+0x138/0x580
[  815.872012]  [<ffffffff816d29f3>] ? _raw_spin_lock+0x23/0x30
[  815.872012]  [<ffffffff816d267a>] ? _raw_spin_unlock+0x1a/0x40
[  815.872012]  [<ffffffff816d0178>] ? __mutex_unlock_slowpath+0x48/0x60
[  815.872012]  [<ffffffff81417dff>] ptmx_open+0x11f/0x180
[  815.872012]  [<ffffffff8119394b>] chrdev_open+0x9b/0x1c0
[  815.872012]  [<ffffffff8118d643>] do_dentry_open+0x203/0x290
[  815.872012]  [<ffffffff811938b0>] ? cdev_put+0x30/0x30
[  815.872012]  [<ffffffff8118d705>] finish_open+0x35/0x50
[  815.872012]  [<ffffffff8119dcce>] do_last+0x6fe/0xe90
[  815.872012]  [<ffffffff8119a7af>] ? link_path_walk+0x7f/0x880
[  815.872012]  [<ffffffff810909d5>] ? cpuacct_charge+0x75/0x80
[  815.872012]  [<ffffffff8119e51c>] path_openat+0xbc/0x4e0
[  815.872012]  [<ffffffff816d0fd0>] ? __schedule+0x400/0x7f0
[  815.872012]  [<ffffffff8140e956>] ? tty_release+0x496/0x580
[  815.872012]  [<ffffffff8119ec11>] do_filp_open+0x41/0xa0
[  815.872012]  [<ffffffff816d267a>] ? _raw_spin_unlock+0x1a/0x40
[  815.872012]  [<ffffffff811abe39>] ? __alloc_fd+0xe9/0x140
[  815.872012]  [<ffffffff8118ea44>] do_sys_open+0xf4/0x1e0
[  815.872012]  [<ffffffff8118eb51>] sys_open+0x21/0x30
[  815.872012]  [<ffffffff816da499>] system_call_fastpath+0x16/0x1b
[  815.872012] Code: 0f 1f 80 00 00 00 00 45 31 e4 eb d7 0f 0b 90 0f 1f 44 00 00 55 48 89 e5 48 83 ec 20 48 89 5d e8 48 89 fb 4c 89 65 f0 4c 89 6d f8 <48> 8b 47 28 48 81 78 58 d1 1c 0$
[  815.872012] RIP  [<ffffffff81207bcc>] devpts_pty_kill+0x1c/0xa0
[  815.872012]  RSP <ffff88007d3e1ac8>
[  815.872012] CR2: 0000000000000028
[  815.897036] ---[ end trace eadf50b7f34e47d5 ]---

Fixes this BUG also:

[  608.366836] BUG: unable to handle kernel NULL pointer dereference at 0000000000000028
[  608.366948] IP: [<ffffffff812078d8>] devpts_kill_index+0x18/0x70
[  608.367050] PGD 7c75b067 PUD 7b919067 PMD 0
[  608.367135] Oops: 0000 [#1] PREEMPT SMP
[  608.367201] Modules linked in: kvm_intel kvm snd_hda_intel snd_hda_codec snd_hwdep snd_pcm snd_seq_midi snd_rawmidi snd_seq_midi_event microcode snd_seq psmouse snd_timer snd_seq_device serio_raw snd mac_hid soundcore snd_page_alloc rfcomm virtio_balloon parport_pc bnep bluetooth ppdev i2c_piix4 lp parport floppy
[  608.367617] CPU 2
[  608.367669] Pid: 1918, comm: stress_test_tty Tainted: G        W    3.8.0-next-20130125+ttypatch-2-xeon #2 Bochs Bochs
[  608.367796] RIP: 0010:[<ffffffff812078d8>]  [<ffffffff812078d8>] devpts_kill_index+0x18/0x70
[  608.367885] RSP: 0018:ffff88007ae41a88  EFLAGS: 00010286
[  608.367951] RAX: ffffffff81417e80 RBX: ffff880036472400 RCX: 0000000180400028
[  608.368010] RDX: ffff880036470004 RSI: 0000000000000004 RDI: 0000000000000000
[  608.368010] RBP: ffff88007ae41a98 R08: 0000000000000000 R09: 0000000000000001
[  608.368010] R10: ffffea0001f22e40 R11: ffffffff814151d5 R12: 0000000000000004
[  608.368010] R13: ffff880036470000 R14: 0000000000000004 R15: ffff880036472400
[  608.368010] FS:  00007ff7a5268700(0000) GS:ffff88007fd00000(0000) knlGS:0000000000000000
[  608.368010] CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
[  608.368010] CR2: 0000000000000028 CR3: 000000007a0fd000 CR4: 00000000000006e0
[  608.368010] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[  608.368010] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
[  608.368010] Process stress_test_tty (pid: 1918, threadinfo ffff88007ae40000, task ffff88003688dc40)
[  608.368010] Stack:
[  608.368010]  ffff880036472400 0000000000000001 ffff88007ae41aa8 ffffffff81417e98
[  608.368010]  ffff88007ae41ac8 ffffffff8140c42b ffff88007ac73100 ffff88007ac73100
[  608.368010]  ffff88007ae41b98 ffffffff8140ead5 ffff88007ae41b38 ffff88007ca40e40
[  608.368010] Call Trace:
[  608.368010]  [<ffffffff81417e98>] pty_unix98_shutdown+0x18/0x20
[  608.368010]  [<ffffffff8140c42b>] release_tty+0x3b/0xe0
[  608.368010]  [<ffffffff8140ead5>] __tty_release+0x575/0x5d0
[  608.368010]  [<ffffffff816d2c63>] ? _raw_spin_lock+0x23/0x30
[  608.368010]  [<ffffffff816d28ea>] ? _raw_spin_unlock+0x1a/0x40
[  608.368010]  [<ffffffff816d03e8>] ? __mutex_unlock_slowpath+0x48/0x60
[  608.368010]  [<ffffffff8140ef79>] tty_open+0x449/0x5f0
[  608.368010]  [<ffffffff8119394b>] chrdev_open+0x9b/0x1c0
[  608.368010]  [<ffffffff8118d643>] do_dentry_open+0x203/0x290
[  608.368010]  [<ffffffff811938b0>] ? cdev_put+0x30/0x30
[  608.368010]  [<ffffffff8118d705>] finish_open+0x35/0x50
[  608.368010]  [<ffffffff8119dcce>] do_last+0x6fe/0xe90
[  608.368010]  [<ffffffff8119a7af>] ? link_path_walk+0x7f/0x880
[  608.368010]  [<ffffffff8119e51c>] path_openat+0xbc/0x4e0
[  608.368010]  [<ffffffff8119ec11>] do_filp_open+0x41/0xa0
[  608.368010]  [<ffffffff816d28ea>] ? _raw_spin_unlock+0x1a/0x40
[  608.368010]  [<ffffffff811abe39>] ? __alloc_fd+0xe9/0x140
[  608.368010]  [<ffffffff8118ea44>] do_sys_open+0xf4/0x1e0
[  608.368010]  [<ffffffff816d2c63>] ? _raw_spin_lock+0x23/0x30
[  608.368010]  [<ffffffff8118eb51>] sys_open+0x21/0x30
[  608.368010]  [<ffffffff816da719>] system_call_fastpath+0x16/0x1b
[  608.368010] Code: ec 48 83 c4 10 5b 41 5c 5d c3 66 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 55 48 89 e5 48 83 ec 10 4c 89 65 f8 41 89 f4 48 89 5d f0 <48> 8b 47 28 48 81 78 58 d1 1c 00 00 74 0b 48 8b 05 4b 66 cf 00
[  608.368010] RIP  [<ffffffff812078d8>] devpts_kill_index+0x18/0x70
[  608.368010]  RSP <ffff88007ae41a88>
[  608.368010] CR2: 0000000000000028
[  608.394153] ---[ end trace afe83b0fb5fbda93 ]---

Reported-by: Ilya Zykov <ilya@ilyx.ru>
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Merge 3.8-rc5 into tty-next 2013-01-25T21:27:36+00:00 Greg Kroah-Hartman gregkh@linuxfoundation.org 2013-01-25T21:27:36+00:00 9f9cba810f36d16f4e64477e879a69f6c47b389d This resolves a number of tty driver merge issues found in linux-next Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
This resolves a number of tty driver merge issues found in linux-next

Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
pty: return EINVAL for TIOCGPTN for BSD ptys 2013-01-17T21:56:57+00:00 Jiri Slaby jslaby@suse.cz 2013-01-11T11:06:27+00:00 ded2f295a36d17838fe97e80d7b6ea83381474f8 Commit bbb63c514a3464342967237a51a21ea8f61ab951 (drivers:tty:fix up ENOIOCTLCMD error handling) changed the default return value from tty ioctl to be ENOTTY and not EINVAL. This is appropriate. But in case of TIOCGPTN for the old BSD ptys glibc started failing because it expects EINVAL to be returned. Only then it continues to obtain the pts name the other way around. So fix this case by explicit return of EINVAL in this case. Signed-off-by: Jiri Slaby <jslaby@suse.cz> Reported-by: Florian Westphal <fw@strlen.de> Cc: Alan Cox <alan@linux.intel.com> Cc: stable <stable@vger.kernel.org> # 3.7+ Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
Commit bbb63c514a3464342967237a51a21ea8f61ab951 (drivers:tty:fix up
ENOIOCTLCMD error handling) changed the default return value from tty
ioctl to be ENOTTY and not EINVAL. This is appropriate.

But in case of TIOCGPTN for the old BSD ptys glibc started failing
because it expects EINVAL to be returned. Only then it continues to
obtain the pts name the other way around.

So fix this case by explicit return of EINVAL in this case.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Reported-by: Florian Westphal <fw@strlen.de>
Cc: Alan Cox <alan@linux.intel.com>
Cc: stable <stable@vger.kernel.org> # 3.7+
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
TTY: do not reset master's packet mode 2013-01-16T06:49:36+00:00 Jiri Slaby jslaby@suse.cz 2013-01-15T22:26:22+00:00 b81273a132177edd806476b953f6afeb17b786d5 Now that login from util-linux is forced to drop all references to a TTY which it wants to hangup (to reach reference count 1) we are seeing issues with telnet. When login closes its last reference to the slave PTY, it also resets packet mode on the *master* side. And we have a race here. What telnet does is fork+exec of `login'. Then there are two scenarios: * `login' closes the slave TTY and resets thus master's packet mode, but even now telnet properly sets the mode, or * `telnetd' sets packet mode on the master, `login' closes the slave TTY and resets master's packet mode. The former case is OK. However the latter happens in much more cases, by the order of magnitude to be precise. So when one tries to login to such a messed telnet setup, they see the following: inux login: ogin incorrect Note the missing first letters -- telnet thinks it is still in the packet mode, so when it receives "linux login" from `login', it considers "l" as the type of the packet and strips it. SuS does not mention how the implementation should behave. Both BSDs I checked (Free and Net) do not reset the flag upon the last close. By this I am resurrecting an old bug, see References. We are hitting it regularly now, i.e. with updated util-linux, ergo login. Here, I am changing a behavior introduced back in 2.1 times. It would better have a long time testing before goes upstream. Signed-off-by: Jiri Slaby <jslaby@suse.cz> Cc: Mauro Carvalho Chehab <mchehab@redhat.com> Cc: Bryan Mason <bmason@redhat.com> References: https://lkml.org/lkml/2009/11/11/223 References: https://bugzilla.redhat.com/show_bug.cgi?id=504703 References: https://bugzilla.novell.com/show_bug.cgi?id=797042 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
Now that login from util-linux is forced to drop all references to a
TTY which it wants to hangup (to reach reference count 1) we are
seeing issues with telnet. When login closes its last reference to the
slave PTY, it also resets packet mode on the *master* side. And we
have a race here.

What telnet does is fork+exec of `login'. Then there are two
scenarios:
* `login' closes the slave TTY and resets thus master's packet mode,
  but even now telnet properly sets the mode, or
* `telnetd' sets packet mode on the master, `login' closes the slave
  TTY and resets master's packet mode.

The former case is OK. However the latter happens in much more cases,
by the order of magnitude to be precise. So when one tries to login to
such a messed telnet setup, they see the following:
inux login:
            ogin incorrect

Note the missing first letters -- telnet thinks it is still in the
packet mode, so when it receives "linux login" from `login', it
considers "l" as the type of the packet and strips it.

SuS does not mention how the implementation should behave. Both BSDs I
checked (Free and Net) do not reset the flag upon the last close.

By this I am resurrecting an old bug, see References. We are hitting
it regularly now, i.e. with updated util-linux, ergo login.

Here, I am changing a behavior introduced back in 2.1 times. It would
better have a long time testing before goes upstream.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Cc: Mauro Carvalho Chehab <mchehab@redhat.com>
Cc: Bryan Mason <bmason@redhat.com>
References: https://lkml.org/lkml/2009/11/11/223
References: https://bugzilla.redhat.com/show_bug.cgi?id=504703
References: https://bugzilla.novell.com/show_bug.cgi?id=797042
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
tty: cleanup checkpatch warning in pty.c 2013-01-16T06:49:36+00:00 Cong Ding dinggnu@gmail.com 2013-01-12T04:01:22+00:00 b9f8033f28448732612e64046b13087b08dd25f7 spaces are used for indent in 3 places of tty/pty.c, we change it to tab. Signed-off-by: Cong Ding <dinggnu@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
spaces are used for indent in 3 places of tty/pty.c, we change it to tab.

Signed-off-by: Cong Ding <dinggnu@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
tty: cleanup the panic message 2013-01-16T06:49:36+00:00 Cong Ding dinggnu@gmail.com 2013-01-12T04:01:21+00:00 82f8c35f86a878a504f92559d631ea03f0f62152 the "\n" in panic message is excess, so we remove it in tty/pty.c as what it is used in other places. Signed-off-by: Cong Ding <dinggnu@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
the "\n" in panic message is excess, so we remove it in tty/pty.c as what it
is used in other places.

Signed-off-by: Cong Ding <dinggnu@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
TTY: switch tty_flip_buffer_push 2013-01-16T06:30:15+00:00 Jiri Slaby jslaby@suse.cz 2013-01-03T14:53:06+00:00 2e124b4a390ca85325fae75764bef92f0547fa25 Now, we start converting tty buffer functions to actually use tty_port. This will allow us to get rid of the need of tty in many call sites. Only tty_port will needed and hence no more tty_port_tty_get in those paths. Now, the one where most of tty_port_tty_get gets removed: tty_flip_buffer_push. IOW we also closed all the races in drivers not using tty_port_tty_get at all yet. Also we move tty_flip_buffer_push declaration from include/linux/tty.h to include/linux/tty_flip.h to all others while we are changing it anyway. Signed-off-by: Jiri Slaby <jslaby@suse.cz> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
Now, we start converting tty buffer functions to actually use
tty_port. This will allow us to get rid of the need of tty in many
call sites. Only tty_port will needed and hence no more
tty_port_tty_get in those paths.

Now, the one where most of tty_port_tty_get gets removed:
tty_flip_buffer_push.

IOW we also closed all the races in drivers not using tty_port_tty_get
at all yet.

Also we move tty_flip_buffer_push declaration from include/linux/tty.h
to include/linux/tty_flip.h to all others while we are changing it
anyway.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>