From: Peter Zijlstra <peterz@infradead.org>
To: mingo@kernel.org, oleg@redhat.com, torvalds@linux-foundation.org
Cc: tglx@linutronix.de, ilya.dryomov@inktank.com,
umgwanakikbuti@gmail.com, linux-kernel@vger.kernel.org,
Peter Zijlstra <peterz@infradead.org>,
Jiri Slaby <jslaby@suse.cz>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Subject: [PATCH 06/11] tty: Deal with nested sleeps
Date: Wed, 24 Sep 2014 10:18:51 +0200 [thread overview]
Message-ID: <20140924082242.323011233@infradead.org> (raw)
In-Reply-To: 20140924081845.572814794@infradead.org
[-- Attachment #1: peterz-might_sleep-tty.patch --]
[-- Type: text/plain, Size: 2848 bytes --]
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.
Cc: Jiri Slaby <jslaby@suse.cz>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
drivers/tty/n_tty.c | 17 +++++------------
1 file changed, 5 insertions(+), 12 deletions(-)
--- a/drivers/tty/n_tty.c
+++ b/drivers/tty/n_tty.c
@@ -2123,7 +2123,7 @@ static ssize_t n_tty_read(struct tty_str
{
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_str
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_str
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_str
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_st
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_st
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_st
}
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);
next prev parent reply other threads:[~2014-09-24 8:39 UTC|newest]
Thread overview: 59+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-09-24 8:18 [PATCH 00/11] nested sleeps, fixes and debug infrastructure Peter Zijlstra
2014-09-24 8:18 ` [PATCH 01/11] locking/mutex: Dont assume TASK_RUNNING Peter Zijlstra
2014-10-28 11:09 ` [tip:sched/core] locking/mutex: Don't " tip-bot for Peter Zijlstra
2014-09-24 8:18 ` [PATCH 02/11] wait: Provide infrastructure to deal with nested blocking Peter Zijlstra
2014-09-29 21:02 ` Oleg Nesterov
2014-10-02 7:37 ` Peter Zijlstra
2014-10-02 21:21 ` Oleg Nesterov
2014-10-28 11:09 ` [tip:sched/core] sched/wait: " tip-bot for Peter Zijlstra
2014-09-24 8:18 ` [PATCH 03/11] wait: Add might_sleep() Peter Zijlstra
2014-10-28 11:09 ` [tip:sched/core] sched/wait: Add might_sleep() checks tip-bot for Peter Zijlstra
2014-09-24 8:18 ` [PATCH 04/11] exit: Deal with nested sleeps Peter Zijlstra
2014-10-28 11:10 ` [tip:sched/core] sched, " tip-bot for Peter Zijlstra
2014-09-24 8:18 ` [PATCH 05/11] inotify: " Peter Zijlstra
2014-10-28 11:10 ` [tip:sched/core] sched, " tip-bot for Peter Zijlstra
2014-09-24 8:18 ` Peter Zijlstra [this message]
2014-10-28 11:10 ` [tip:sched/core] sched, tty: " tip-bot for Peter Zijlstra
2014-09-24 8:18 ` [PATCH 07/11] smp: Correctly deal " Peter Zijlstra
2014-10-28 11:11 ` [tip:sched/core] sched, " tip-bot for Peter Zijlstra
2014-09-24 8:18 ` [PATCH 08/11] module: Fix nested sleep Peter Zijlstra
2014-09-29 22:18 ` Oleg Nesterov
2014-09-30 13:43 ` Peter Zijlstra
2014-10-28 11:11 ` [tip:sched/core] sched, modules: Fix nested sleep in add_unformed_module() tip-bot for Peter Zijlstra
2014-09-24 8:18 ` [PATCH 09/11] net: Clean up sk_wait_event() vs might_sleep() Peter Zijlstra
2014-09-24 8:36 ` Peter Zijlstra
2014-10-28 11:11 ` [tip:sched/core] sched, net: Clean up sk_wait_event() vs. might_sleep() tip-bot for Peter Zijlstra
2014-09-24 8:18 ` [PATCH 10/11] sched: Debug nested sleeps Peter Zijlstra
2014-09-29 22:13 ` Oleg Nesterov
2014-09-30 13:49 ` Peter Zijlstra
2014-09-30 21:47 ` Oleg Nesterov
2014-10-01 16:10 ` Peter Zijlstra
2014-10-01 18:35 ` Oleg Nesterov
2014-10-02 9:07 ` Peter Zijlstra
2014-10-02 21:34 ` Oleg Nesterov
2014-10-28 11:11 ` [tip:sched/core] " tip-bot for Peter Zijlstra
2014-09-24 8:18 ` [PATCH 11/11] sched: Exclude cond_resched() from nested sleep test Peter Zijlstra
2014-10-28 11:12 ` [tip:sched/core] " tip-bot for Peter Zijlstra
2014-09-25 8:30 ` [PATCH 00/11] nested sleeps, fixes and debug infrastructure Mike Galbraith
2014-09-25 9:06 ` Peter Zijlstra
2014-09-25 9:10 ` Mike Galbraith
2014-09-25 9:15 ` Peter Zijlstra
2014-09-25 9:56 ` Mike Galbraith
2014-09-25 13:59 ` BUG: sleeping function called from invalid context at drivers/cpufreq/cpufreq.c:370 Mike Galbraith
2014-09-26 6:24 ` Mike Galbraith
2014-09-26 7:54 ` Mike Galbraith
2014-09-26 14:10 ` Rafael J. Wysocki
2014-09-26 22:44 ` Rafael J. Wysocki
2014-09-27 6:14 ` Mike Galbraith
2014-09-27 19:57 ` Rafael J. Wysocki
2014-10-02 10:22 ` [PATCH 00/11] nested sleeps, fixes and debug infrastructure Peter Zijlstra
2014-10-02 12:15 ` Peter Zijlstra
2014-10-27 13:41 ` Peter Zijlstra
2014-10-28 0:07 ` Oleg Nesterov
2014-10-28 8:23 ` Peter Zijlstra
2014-10-29 0:00 ` Oleg Nesterov
2014-10-29 9:35 ` Peter Zijlstra
2014-10-29 11:31 ` Peter Zijlstra
2014-10-29 11:36 ` Peter Zijlstra
2014-10-29 14:26 ` Peter Zijlstra
2014-11-04 16:08 ` [tip:sched/core] audit, sched/wait: Fixup kauditd_thread() wait loop tip-bot for Peter Zijlstra
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