tracing: Change syscall_*regfunc() to check PF_KTHREAD and use for_each_process_thread() (8063e41d) · Commits · 戴 / test

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:

Oleg Nesterov <oleg@redhat.com> Signed-off-by:

Steven Rostedt <rostedt@goodmis.org>

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

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