diff options
author | Peter Zijlstra <peterz@infradead.org> | 2014-09-24 10:18:51 +0200 |
---|---|---|
committer | Ingo Molnar <mingo@kernel.org> | 2014-10-28 10:56:10 +0100 |
commit | 97d9e28d1a27b84a6a0b155f2390289afa279341 (patch) | |
tree | 795f01ef74c97cb2397f0abddb17234c0b264b75 /drivers | |
parent | e23738a7300a7591a57a22f47b813fd1b53ec404 (diff) |
sched, tty: Deal with nested sleeps
n_tty_{read,write} are wait loops with sleeps in. Wait loops rely on
task_struct::state and sleeps do too, since that's the only means of
actually sleeping. Therefore the nested sleeps destroy the wait loop
state.
Fix this by using the new woken_wake_function and wait_woken() stuff,
which registers wakeups in wait and thereby allows shrinking the
task_state::state changes to the actual sleep part.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: tglx@linutronix.de
Cc: ilya.dryomov@inktank.com
Cc: umgwanakikbuti@gmail.com
Cc: oleg@redhat.com
Link: http://lkml.kernel.org/r/20140924082242.323011233@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'drivers')
-rw-r--r-- | drivers/tty/n_tty.c | 17 |
1 files changed, 5 insertions, 12 deletions
diff --git a/drivers/tty/n_tty.c b/drivers/tty/n_tty.c index 89c4cee253e3..fb3f519b803f 100644 --- a/drivers/tty/n_tty.c +++ b/drivers/tty/n_tty.c @@ -2123,7 +2123,7 @@ static ssize_t n_tty_read(struct tty_struct *tty, struct file *file, { struct n_tty_data *ldata = tty->disc_data; unsigned char __user *b = buf; - DECLARE_WAITQUEUE(wait, current); + DEFINE_WAIT_FUNC(wait, woken_wake_function); int c; int minimum, time; ssize_t retval = 0; @@ -2186,10 +2186,6 @@ static ssize_t n_tty_read(struct tty_struct *tty, struct file *file, nr--; break; } - /* This statement must be first before checking for input - so that any interrupt will set the state back to - TASK_RUNNING. */ - set_current_state(TASK_INTERRUPTIBLE); if (((minimum - (b - buf)) < ldata->minimum_to_wake) && ((minimum - (b - buf)) >= 1)) @@ -2220,13 +2216,13 @@ static ssize_t n_tty_read(struct tty_struct *tty, struct file *file, n_tty_set_room(tty); up_read(&tty->termios_rwsem); - timeout = schedule_timeout(timeout); + timeout = wait_woken(&wait, TASK_INTERRUPTIBLE, + timeout); down_read(&tty->termios_rwsem); continue; } } - __set_current_state(TASK_RUNNING); /* Deal with packet mode. */ if (packet && b == buf) { @@ -2273,7 +2269,6 @@ static ssize_t n_tty_read(struct tty_struct *tty, struct file *file, mutex_unlock(&ldata->atomic_read_lock); - __set_current_state(TASK_RUNNING); if (b - buf) retval = b - buf; @@ -2306,7 +2301,7 @@ static ssize_t n_tty_write(struct tty_struct *tty, struct file *file, const unsigned char *buf, size_t nr) { const unsigned char *b = buf; - DECLARE_WAITQUEUE(wait, current); + DEFINE_WAIT_FUNC(wait, woken_wake_function); int c; ssize_t retval = 0; @@ -2324,7 +2319,6 @@ static ssize_t n_tty_write(struct tty_struct *tty, struct file *file, add_wait_queue(&tty->write_wait, &wait); while (1) { - set_current_state(TASK_INTERRUPTIBLE); if (signal_pending(current)) { retval = -ERESTARTSYS; break; @@ -2378,12 +2372,11 @@ static ssize_t n_tty_write(struct tty_struct *tty, struct file *file, } up_read(&tty->termios_rwsem); - schedule(); + wait_woken(&wait, TASK_INTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT); down_read(&tty->termios_rwsem); } break_out: - __set_current_state(TASK_RUNNING); remove_wait_queue(&tty->write_wait, &wait); if (b - buf != nr && tty->fasync) set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags); |