korg/linux
0
0
Fork 0
mirror of https://mirrors.bfsu.edu.cn/git/linux.git synced 2025-01-19 04:14:49 +08:00
Code Issues Packages Projects Releases Wiki Activity

posix-cpu-timers: Assert task sighand is locked while starting cputime counter

Browse Source 
Starting the process wide cputime counter needs to be done in the same
sighand locking sequence than actually arming the related timer otherwise
this races against concurrent timers setting/expiring in the same
threadgroup.

Detecting that the cputime counter is started without holding the sighand
lock is a first step toward debugging such situations.

Suggested-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20210726125513.271824-2-frederic@kernel.org
This commit is contained in:
Frederic Weisbecker 2021-07-26 14:55:08 +02:00 committed by Thomas Gleixner
parent 1dae37c7e4
commit a5dec9f82a
3 changed files with 23 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
include/linux/sched/signal.h
View File

@ -714,6 +714,12 @@ static inline void unlock_task_sighand(struct task_struct *task,
spin_unlock_irqrestore(&task->sighand->siglock, *flags);
}
#ifdef CONFIG_LOCKDEP
extern void lockdep_assert_task_sighand_held(struct task_struct *task);
#else
static inline void lockdep_assert_task_sighand_held(struct task_struct *task) { }
#endif
static inline unsigned long task_rlimit(const struct task_struct *task,
unsigned int limit)
{

15
kernel/signal.c
View File

@ -1413,6 +1413,21 @@ struct sighand_struct *__lock_task_sighand(struct task_struct *tsk,
return sighand;
}
#ifdef CONFIG_LOCKDEP
void lockdep_assert_task_sighand_held(struct task_struct *task)
{
struct sighand_struct *sighand;
rcu_read_lock();
sighand = rcu_dereference(task->sighand);
if (sighand)
lockdep_assert_held(&sighand->siglock);
else
WARN_ON_ONCE(1);
rcu_read_unlock();
}
#endif
/*
* send signal info to all the members of a group
*/

2
kernel/time/posix-cpu-timers.c
View File

@ -291,6 +291,8 @@ static void thread_group_start_cputime(struct task_struct *tsk, u64 *samples)
struct thread_group_cputimer *cputimer = &tsk->signal->cputimer;
struct posix_cputimers *pct = &tsk->signal->posix_cputimers;
lockdep_assert_task_sighand_held(tsk);
/* Check if cputimer isn't running. This is accessed without locking. */
if (!READ_ONCE(pct->timers_active)) {
struct task_cputime sum;