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: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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@ -492,33 +492,31 @@ static int sys_tracepoint_refcount;
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void syscall_regfunc(void)
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void syscall_regfunc(void)
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{
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{
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unsigned long flags;
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struct task_struct *p, *t;
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struct task_struct *g, *t;
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if (!sys_tracepoint_refcount) {
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if (!sys_tracepoint_refcount) {
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read_lock_irqsave(&tasklist_lock, flags);
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read_lock(&tasklist_lock);
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do_each_thread(g, t) {
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for_each_process_thread(p, t) {
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/* Skip kernel threads. */
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/* Skip kernel threads. */
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if (t->mm)
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if (!(t->flags & PF_KTHREAD))
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set_tsk_thread_flag(t, TIF_SYSCALL_TRACEPOINT);
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set_tsk_thread_flag(t, TIF_SYSCALL_TRACEPOINT);
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} while_each_thread(g, t);
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}
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read_unlock_irqrestore(&tasklist_lock, flags);
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read_unlock(&tasklist_lock);
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}
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}
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sys_tracepoint_refcount++;
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sys_tracepoint_refcount++;
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}
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}
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void syscall_unregfunc(void)
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void syscall_unregfunc(void)
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{
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{
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unsigned long flags;
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struct task_struct *p, *t;
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struct task_struct *g, *t;
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sys_tracepoint_refcount--;
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sys_tracepoint_refcount--;
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if (!sys_tracepoint_refcount) {
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if (!sys_tracepoint_refcount) {
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read_lock_irqsave(&tasklist_lock, flags);
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read_lock(&tasklist_lock);
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do_each_thread(g, t) {
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for_each_process_thread(p, t) {
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clear_tsk_thread_flag(t, TIF_SYSCALL_TRACEPOINT);
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clear_tsk_thread_flag(t, TIF_SYSCALL_TRACEPOINT);
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} while_each_thread(g, t);
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}
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read_unlock_irqrestore(&tasklist_lock, flags);
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read_unlock(&tasklist_lock);
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}
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}
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}
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}
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#endif
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#endif
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