[dm-devel] [PATCH v2 23/23] multipathd: fix signal blocking logic

[Hannes Reinecke]

On 03/06/2018 12:15 AM, Martin Wilck wrote:
> multipathd is supposed to block all signals in all threads, except
> the uxlsnr thread which handles termination and reconfiguration
> signals (SIGUSR1) in its ppoll() call, SIGUSR2 in the waiter thread
> and the marginal path checker thread, and occasional SIGALRM. The current
> logic does exactly the oppsite, it blocks termination signals in SIGPOLL and
> allows multipathd to be killed e.g. by SIGALRM.
> 
> Fix that by inverting the logic. The argument to pthread_sigmask and
> ppoll is the set of *blocked* signals, not vice versa.
> 
> The marginal paths code needs to unblock SIGUSR2 now explicity, as
> the dm-event waiter code already does. Doing this with pselect()
> avoids asynchronous cancellation.
> 
> Fixes: 810082e "libmultipath, multipathd: Rework SIGPIPE handling"
> Fixes: 534ec4c "multipathd: Ensure that SIGINT, SIGTERM, SIGHUP and SIGUSR1
> are delivered to the uxsock thread"
> 
> Signed-off-by: Martin Wilck <mwilck at suse.com>
> ---
>  libmultipath/io_err_stat.c | 17 ++++++++++++++++-
>  multipathd/main.c          |  7 +++++--
>  multipathd/uxlsnr.c        | 10 +++++-----
>  3 files changed, 26 insertions(+), 8 deletions(-)
> 
Sigh.
Will we ever get signal handling correct?

Reviewed-by: Hannes Reinecke <hare at suse.com>

Cheers,

Hannes
-- 
Dr. Hannes Reinecke		   Teamlead Storage & Networking
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