Commit 622c72b6 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge tag 'timers-urgent-2021-11-14' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 

Pull timer fix from Thomas Gleixner:
 "A single fix for POSIX CPU timers to address a problem where POSIX CPU
  timer delivery stops working for a new child task because
  copy_process() copies state information which is only valid for the
  parent task"

* tag 'timers-urgent-2021-11-14' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  posix-cpu-timers: Clear task::posix_cputimers_work in copy_process()
parents c36e33e2 ca7752ca

include/linux/posix-timers.h

+2 −0
Original line number Diff line number Diff line
@@ -184,8 +184,10 @@ static inline void posix_cputimers_group_init(struct posix_cputimers *pct, 
#endif



#ifdef CONFIG_POSIX_CPU_TIMERS_TASK_WORK

void clear_posix_cputimers_work(struct task_struct *p);

void posix_cputimers_init_work(void);

#else

static inline void clear_posix_cputimers_work(struct task_struct *p) { }

static inline void posix_cputimers_init_work(void) { }

#endif

kernel/fork.c

+1 −0
Original line number Diff line number Diff line
@@ -2277,6 +2277,7 @@ static __latent_entropy struct task_struct *copy_process( 
	p->pdeath_signal = 0;

	INIT_LIST_HEAD(&p->thread_group);

	p->task_works = NULL;

	clear_posix_cputimers_work(p);



#ifdef CONFIG_KRETPROBES

	p->kretprobe_instances.first = NULL;

kernel/time/posix-cpu-timers.c

+17 −2
Original line number Diff line number Diff line
@@ -1158,14 +1158,29 @@ static void posix_cpu_timers_work(struct callback_head *work) 
	handle_posix_cpu_timers(current);

}



/*

 * Clear existing posix CPU timers task work.

 */

void clear_posix_cputimers_work(struct task_struct *p)

{

	/*

	 * A copied work entry from the old task is not meaningful, clear it.

	 * N.B. init_task_work will not do this.

	 */

	memset(&p->posix_cputimers_work.work, 0,

	       sizeof(p->posix_cputimers_work.work));

	init_task_work(&p->posix_cputimers_work.work,

		       posix_cpu_timers_work);

	p->posix_cputimers_work.scheduled = false;

}



/*

 * Initialize posix CPU timers task work in init task. Out of line to

 * keep the callback static and to avoid header recursion hell.

 */

void __init posix_cputimers_init_work(void)

{

	init_task_work(&current->posix_cputimers_work.work,

		       posix_cpu_timers_work);

	clear_posix_cputimers_work(current);

}



/*