On 03/06/2018 10:18 PM, Martin Wilck wrote:
> It's wrong, and unnecessary, to call pthread_kill after
> pthread_cancel. I have observed cases where the io_err checker
> thread hung in libpthread after receiving the USR2 signal, in particular
> when multipathd is run under strace. (If multipathd is killed with
> SIGINT under strace, and the io_error thread is running, it happens
> almost every time). If this happens, the io_err thread
> tries to obtain a mutex in the urcu code (presumably rcu_unregister_thread())
> and the main thread hangs in pthread_join().
>
> With the change from this patch, the thread is shut down cleanly. I haven't
> observed the hang under strace with the patch.
>
> Signed-off-by: Martin Wilck <mwilck@xxxxxxxx>
> ---
> libmultipath/io_err_stat.c | 1 -
> 1 file changed, 1 deletion(-)
>
> diff --git a/libmultipath/io_err_stat.c b/libmultipath/io_err_stat.c
> index 00bac9e0e755..536ba87968fd 100644
> --- a/libmultipath/io_err_stat.c
> +++ b/libmultipath/io_err_stat.c
> @@ -749,7 +749,6 @@ destroy_ctx:
> void stop_io_err_stat_thread(void)
> {
> pthread_cancel(io_err_stat_thr);
> - pthread_kill(io_err_stat_thr, SIGUSR2);
> pthread_join(io_err_stat_thr, NULL);
> free_io_err_pathvec(paths);
> io_destroy(ioctx);
>
Good point.
Reviewed-by: Hannes Reinecke <hare@xxxxxxxx>
Cheers,
Hannes
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Dr. Hannes Reinecke Teamlead Storage & Networking
hare@xxxxxxx +49 911 74053 688
SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg
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HRB 21284 (AG Nürnberg)
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