kernel.git/drivers/tty/pty.c, branch linux-5.13.y

tty: create internal tty.h file

2021-04-15T08:22:17Z

There are a number of functions and #defines in include/linux/tty.h that do not belong there as they are private to the tty core code. Create an initial drivers/tty/tty.h file and copy the odd "tty logging" macros into it to seed the file with some initial things that we know nothing outside of the tty core should be calling. Cc: Tetsuo Handa Cc: Jiri Slaby Link: https://lore.kernel.org/r/20210408125134.3016837-2-gregkh@linuxfoundation.org Signed-off-by: Greg Kroah-Hartman

tty: pty: Add a blank line after declarations

2021-04-02T14:12:35Z

Add a blank line after declarations, reported by checkpatch.pl. Signed-off-by: Xiaofei Tan Link: https://lore.kernel.org/r/1617351990-5189-1-git-send-email-tanxiaofei@huawei.com Signed-off-by: Greg Kroah-Hartman

Revert "drivers:tty:pty: Fix a race causing data loss on close"

2021-03-10T08:27:56Z

This reverts commit 33d4ae98859873ddd49e22e4ca724387548b3d89. Pierre-Louis writes: Our SOF/audio CI shows an across-the-board regression when we try v5.12-rc1, specifically on pause/resume tests with an interactive terminal running 'aplay -i' commands managed by expect to simulate the user pressing the space bar to pause/unpause. It turns out the processes are not longer killed and the audio devices remain busy (see publicly available test results listed below). git bisect points to commit 33d4ae9885987 ("drivers:tty:pty: Fix a race causing data loss on close"). Reverting the patch fixes the issue on all test devices. Further analysis with Corey Minyard points to a problem where a slave tty will not get a SIGHUP when the master is closed. So revert this for now: Reported-by: Pierre-Louis Bossart Link: https://lore.kernel.org/r/00154592-c5ee-aaba-956e-b265473b53bc@linux.intel.com Cc: Corey Minyard Cc: Jiri Slaby Cc: Mark Brown , Fixes: 33d4ae988598 ("drivers:tty:pty: Fix a race causing data loss on close") Signed-off-by: Greg Kroah-Hartman

drivers:tty:pty: Fix a race causing data loss on close

2021-01-07T15:30:55Z

Remove the tty_vhangup() from the pty code and just release the redirect. The tty_vhangup() results in data loss and data out of order issues. If you write to a pty master an immediately close the pty master, the receiver might get a chunk of data dropped, but then receive some later data. That's obviously something rather unexpected for a user. It certainly confused my test program. It turns out that tty_vhangup() on the slave pty gets called from pty_close(), and that causes the data on the slave side to be flushed, but due to races more data can be copied into the slave side's buffer after that. Consider the following sequence: thread1 thread2 thread3 ------- ------- ------- | |-write data into buffer, | | n_tty buffer is filled | | along with other buffers | |-pty_close(master) | |--tty_vhangup(slave) | |---tty_ldisc_hangup() | |----n_tty_flush_buffer() | |-----reset_buffer_flags() |-n_tty_read() | |--up_read(&tty->termios_rwsem); | |------down_read(&tty->termios_rwsem) | |------clear n_tty buffer contents | |------up_read(&tty->termios_rwsem) |--tty_buffer_flush_work() | |--schedules work calling | | flush_to_ldisc() | | |-flush_to_ldisc() | |--receive_buf() | |---tty_port_default_receive_buf() | |----tty_ldisc_receive_buf() | |-----n_tty_receive_buf2() | |------n_tty_receive_buf_common() | |-------down_read(&tty->termios_rwsem) | |-------__receive_buf() | | copies data into n_tty buffer | |-------up_read(&tty->termios_rwsem) |--down_read(&tty->termios_rwsem) |--copy buffer data to user >From this sequence, you can see that thread2 writes to the buffer then only clears the part of the buffer in n_tty. The n_tty receive buffer code then copies more data into the n_tty buffer. But part of the vhangup, releasing the redirect, is still required to avoid issues with consoles running on pty slaves. So do that. As far as I can tell, that is all that should be required. Signed-off-by: Corey Minyard Link: https://lore.kernel.org/r/20201124004902.1398477-3-minyard@acm.org Signed-off-by: Greg Kroah-Hartman

tty: pty, remove BUG_ON from pty_close

2021-01-07T15:17:31Z

tty->ops->close is always called with a valid tty, so the BUG_ON cannot trigger. Signed-off-by: Jiri Slaby Link: https://lore.kernel.org/r/20210105120239.28031-5-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman

tty: pty: Provide descriptions for the 'file' parameters

2020-11-06T09:54:04Z

Fixes the following W=1 kernel build warning(s): drivers/tty/pty.c:710: warning: Function parameter or member 'file' not described in 'ptm_unix98_lookup' drivers/tty/pty.c:726: warning: Function parameter or member 'file' not described in 'pts_unix98_lookup' Cc: Greg Kroah-Hartman Cc: Jiri Slaby Cc: "C. Scott Ananian" Signed-off-by: Lee Jones Link: https://lore.kernel.org/r/20201104193549.4026187-17-lee.jones@linaro.org Signed-off-by: Greg Kroah-Hartman

pty: do tty_flip_buffer_push without port->lock in pty_write

2020-09-04T16:10:30Z

b6da31b2c07c "tty: Fix data race in tty_insert_flip_string_fixed_flag" puts tty_flip_buffer_push under port->lock introducing the following possible circular locking dependency: [30129.876566] ====================================================== [30129.876566] WARNING: possible circular locking dependency detected [30129.876567] 5.9.0-rc2+ #3 Tainted: G S W [30129.876568] ------------------------------------------------------ [30129.876568] sysrq.sh/1222 is trying to acquire lock: [30129.876569] ffffffff92c39480 (console_owner){....}-{0:0}, at: console_unlock+0x3fe/0xa90 [30129.876572] but task is already holding lock: [30129.876572] ffff888107cb9018 (&pool->lock/1){-.-.}-{2:2}, at: show_workqueue_state.cold.55+0x15b/0x6ca [30129.876576] which lock already depends on the new lock. [30129.876577] the existing dependency chain (in reverse order) is: [30129.876578] -> #3 (&pool->lock/1){-.-.}-{2:2}: [30129.876581] _raw_spin_lock+0x30/0x70 [30129.876581] __queue_work+0x1a3/0x10f0 [30129.876582] queue_work_on+0x78/0x80 [30129.876582] pty_write+0x165/0x1e0 [30129.876583] n_tty_write+0x47f/0xf00 [30129.876583] tty_write+0x3d6/0x8d0 [30129.876584] vfs_write+0x1a8/0x650 [30129.876588] -> #2 (&port->lock#2){-.-.}-{2:2}: [30129.876590] _raw_spin_lock_irqsave+0x3b/0x80 [30129.876591] tty_port_tty_get+0x1d/0xb0 [30129.876592] tty_port_default_wakeup+0xb/0x30 [30129.876592] serial8250_tx_chars+0x3d6/0x970 [30129.876593] serial8250_handle_irq.part.12+0x216/0x380 [30129.876593] serial8250_default_handle_irq+0x82/0xe0 [30129.876594] serial8250_interrupt+0xdd/0x1b0 [30129.876595] __handle_irq_event_percpu+0xfc/0x850 [30129.876602] -> #1 (&port->lock){-.-.}-{2:2}: [30129.876605] _raw_spin_lock_irqsave+0x3b/0x80 [30129.876605] serial8250_console_write+0x12d/0x900 [30129.876606] console_unlock+0x679/0xa90 [30129.876606] register_console+0x371/0x6e0 [30129.876607] univ8250_console_init+0x24/0x27 [30129.876607] console_init+0x2f9/0x45e [30129.876609] -> #0 (console_owner){....}-{0:0}: [30129.876611] __lock_acquire+0x2f70/0x4e90 [30129.876612] lock_acquire+0x1ac/0xad0 [30129.876612] console_unlock+0x460/0xa90 [30129.876613] vprintk_emit+0x130/0x420 [30129.876613] printk+0x9f/0xc5 [30129.876614] show_pwq+0x154/0x618 [30129.876615] show_workqueue_state.cold.55+0x193/0x6ca [30129.876615] __handle_sysrq+0x244/0x460 [30129.876616] write_sysrq_trigger+0x48/0x4a [30129.876616] proc_reg_write+0x1a6/0x240 [30129.876617] vfs_write+0x1a8/0x650 [30129.876619] other info that might help us debug this: [30129.876620] Chain exists of: [30129.876621] console_owner --> &port->lock#2 --> &pool->lock/1 [30129.876625] Possible unsafe locking scenario: [30129.876626] CPU0 CPU1 [30129.876626] ---- ---- [30129.876627] lock(&pool->lock/1); [30129.876628] lock(&port->lock#2); [30129.876630] lock(&pool->lock/1); [30129.876631] lock(console_owner); [30129.876633] *** DEADLOCK *** [30129.876634] 5 locks held by sysrq.sh/1222: [30129.876634] #0: ffff8881d3ce0470 (sb_writers#3){.+.+}-{0:0}, at: vfs_write+0x359/0x650 [30129.876637] #1: ffffffff92c612c0 (rcu_read_lock){....}-{1:2}, at: __handle_sysrq+0x4d/0x460 [30129.876640] #2: ffffffff92c612c0 (rcu_read_lock){....}-{1:2}, at: show_workqueue_state+0x5/0xf0 [30129.876642] #3: ffff888107cb9018 (&pool->lock/1){-.-.}-{2:2}, at: show_workqueue_state.cold.55+0x15b/0x6ca [30129.876645] #4: ffffffff92c39980 (console_lock){+.+.}-{0:0}, at: vprintk_emit+0x123/0x420 [30129.876648] stack backtrace: [30129.876649] CPU: 3 PID: 1222 Comm: sysrq.sh Tainted: G S W 5.9.0-rc2+ #3 [30129.876649] Hardware name: Intel Corporation 2012 Client Platform/Emerald Lake 2, BIOS ACRVMBY1.86C.0078.P00.1201161002 01/16/2012 [30129.876650] Call Trace: [30129.876650] dump_stack+0x9d/0xe0 [30129.876651] check_noncircular+0x34f/0x410 [30129.876653] __lock_acquire+0x2f70/0x4e90 [30129.876656] lock_acquire+0x1ac/0xad0 [30129.876658] console_unlock+0x460/0xa90 [30129.876660] vprintk_emit+0x130/0x420 [30129.876660] printk+0x9f/0xc5 [30129.876661] show_pwq+0x154/0x618 [30129.876662] show_workqueue_state.cold.55+0x193/0x6ca [30129.876664] __handle_sysrq+0x244/0x460 [30129.876665] write_sysrq_trigger+0x48/0x4a [30129.876665] proc_reg_write+0x1a6/0x240 [30129.876666] vfs_write+0x1a8/0x650 It looks like the commit was aimed to protect tty_insert_flip_string and there is no need for tty_flip_buffer_push to be under this lock. Fixes: b6da31b2c07c ("tty: Fix data race in tty_insert_flip_string_fixed_flag") Signed-off-by: Artem Savkov Acked-by: Jiri Slaby Link: https://lore.kernel.org/r/20200902120045.3693075-1-asavkov@redhat.com Signed-off-by: Greg Kroah-Hartman

tty: fix kernel-doc

2020-08-18T11:51:18Z

With W=1, the kernel-doc checker complains quite a lot in the tty layer. Over the time, many documented parameters were renamed, removed or switched from tty to tty_port and similar. Some were mistyped in the doc too. So fix all these in the tty core. (But do not add the missing ones which the checker complains about too. Not now.) The rest in the tty layer will follow in the next patches. Signed-off-by: Jiri Slaby Link: https://lore.kernel.org/r/20200818085655.12071-4-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman

pty: fix compat ioctls

2018-10-13T04:50:51Z

pointer-taking ones need compat_ptr(); int-taking one doesn't. Signed-off-by: Al Viro

pty: fix O_CLOEXEC for TIOCGPTPEER

2018-07-21T07:08:47Z

It was being ignored because the flags were not passed to fd allocation. Fixes: 54ebbfb16034 ("tty: add TIOCGPTPEER ioctl") Signed-off-by: Matthijs van Duin Acked-by: Aleksa Sarai Cc: stable Signed-off-by: Greg Kroah-Hartman