Messages in this thread | | | Date | Wed, 26 Oct 2011 18:54:00 +0200 | From | Oleg Nesterov <> | Subject | Re: [PATCH] exec: log when wait_for_dump_helpers aborts due to a signal |
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On 10/25, Mandeep Singh Baines wrote: > > To allow coredump pipe readers to look at /proc/<pid> of the crashing > process, the kernel waits for the reader to exit. However, the wait > is silently aborted if the crashing process is signalled.
Well, yes... But note that this signal_pending() is only used because with TIF_SIGPENDING we have the problems anyway.
Oh. I promise myself I'll make do_coredump() killable and cleanup this all every time I look at this code...
> This patch, logs whenever wait_for_dump_helpers is aborted or in order > to assist in debugging cases where /proc/<pid> is gone.
I don't really understand why this is useful. The reader process can complain if it can't collect the data (say, /proc/pid goes away or EOF doesn't come).
As for the patch itself,
> - while ((pipe->readers > 1) && (!signal_pending(current))) { > + while (pipe->readers > 1) { > + if (signal_pending(current)) { > + pr_info("wait_for_dump_helpers[%d]: " > + "aborted due to signal\n", > + task_pid_nr(current)); > + break; > + } > + > wake_up_interruptible_sync(&pipe->wait);
This can't help in general. If signal_pending() == T, it is quite possible that pipe_write() already failed before.
Oleg.
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