Messages in this thread Patch in this message |  | | Date | Thu, 23 Oct 2014 21:53:37 +0200 | From | Oleg Nesterov <> | Subject | Re: rcu_preempt detected stalls. |
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On 10/23, Paul E. McKenney wrote: > > OK, so making each pass through the loop a separate RCU read-side critical > section might be considered to be suppressing notification of an error > condition?
I agree, this change probably makes sense anyway. Personally I'd prefer the version below (somehow I hate multiple unlock's), but I won't insist.
Oleg.
--- x/kernel/signal.c +++ x/kernel/signal.c @@ -1331,21 +1331,19 @@ int kill_pid_info(int sig, struct siginf int error = -ESRCH; struct task_struct *p; - rcu_read_lock(); retry: + rcu_read_lock(); p = pid_task(pid, PIDTYPE_PID); - if (p) { + if (p) error = group_send_sig_info(sig, info, p); - if (unlikely(error == -ESRCH)) - /* - * The task was unhashed in between, try again. - * If it is dead, pid_task() will return NULL, - * if we race with de_thread() it will find the - * new leader. - */ - goto retry; - } rcu_read_unlock(); + /* + * The task was unhashed in between, try again. If it is dead, + * pid_task() will return NULL, if we race with de_thread() it + * will find the new leader. + */ + if (p && error == -ESRCH)) + goto retry; return error; }
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