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Commit 8063e41d authored by Oleg Nesterov's avatar Oleg Nesterov Committed by Steven Rostedt
Browse files

tracing: Change syscall_*regfunc() to check PF_KTHREAD and use for_each_process_thread() 

1. Remove _irqsafe from syscall_regfunc/syscall_unregfunc,
   read_lock(tasklist) doesn't need to disable irqs.

2. Change this code to avoid the deprecated do_each_thread()
   and use for_each_process_thread() (stolen from the patch
   from Frederic).

3. Change syscall_regfunc() to check PF_KTHREAD to skip
   the kernel threads, ->mm != NULL is the common mistake.

   Note: probably this check should be simply removed, needs
   another patch.

[fweisbec@gmail.com: s/do_each_thread/for_each_process_thread/]
Link: http://lkml.kernel.org/p/20140413185918.GC20668@redhat.com



Signed-off-by: default avatarOleg Nesterov <oleg@redhat.com>
Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
parent 4af4206b

kernel/tracepoint.c

+11 −13
Original line number Diff line number Diff line
@@ -492,33 +492,31 @@ static int sys_tracepoint_refcount; 


void syscall_regfunc(void)

{

	unsigned long flags;

	struct task_struct *g, *t;

	struct task_struct *p, *t;



	if (!sys_tracepoint_refcount) {

		read_lock_irqsave(&tasklist_lock, flags);

		do_each_thread(g, t) {

		read_lock(&tasklist_lock);

		for_each_process_thread(p, t) {

			/* Skip kernel threads. */

			if (t->mm)

			if (!(t->flags & PF_KTHREAD))

				set_tsk_thread_flag(t, TIF_SYSCALL_TRACEPOINT);

		} while_each_thread(g, t);

		read_unlock_irqrestore(&tasklist_lock, flags);

		}

		read_unlock(&tasklist_lock);

	}

	sys_tracepoint_refcount++;

}



void syscall_unregfunc(void)

{

	unsigned long flags;

	struct task_struct *g, *t;

	struct task_struct *p, *t;



	sys_tracepoint_refcount--;

	if (!sys_tracepoint_refcount) {

		read_lock_irqsave(&tasklist_lock, flags);

		do_each_thread(g, t) {

		read_lock(&tasklist_lock);

		for_each_process_thread(p, t) {

			clear_tsk_thread_flag(t, TIF_SYSCALL_TRACEPOINT);

		} while_each_thread(g, t);

		read_unlock_irqrestore(&tasklist_lock, flags);

		}

		read_unlock(&tasklist_lock);

	}

}

#endif