[dm-devel] [RFC PATCH 5/6] multipathd: add code to handle blocked signals

[Benjamin Marzinski]

On Fri, Jan 04, 2019 at 06:59:13PM +0100, Martin Wilck wrote:
> multipathd blocks all signals except in the uxlsnr thread.
> Add some code to handle signals even while they're blocked.
> 
> If a shutdown signal is received, deliver_pending_signals() returns
> TRUE. This is not the same as should_exit(), it's just a friendly
> warning to the caller that shutdown/thread cancellation is imminent.
> 
> Signed-off-by: Martin Wilck <mwilck at suse.com>
> ---
>  multipathd/main.c | 25 +++++++++++++++++++++++++
>  multipathd/main.h |  1 +
>  2 files changed, 26 insertions(+)
> 
> diff --git a/multipathd/main.c b/multipathd/main.c
> index 569a27ac..6276d34c 100644
> --- a/multipathd/main.c
> +++ b/multipathd/main.c
> @@ -2614,6 +2614,31 @@ signal_init(void)
>  	signal_set(SIGPIPE, sigend);
>  }
>  
> +bool deliver_pending_signals(void)
> +{
> +	sigset_t set;
> +	bool ret = exit_sig;
> +
> +	if (sigpending(&set) != 0)
> +		return false;

shouldn't this return ret instead of false?

-Ben

> +
> +	if (sigismember(&set, SIGTERM) ||
> +	    sigismember(&set, SIGPIPE) ||
> +	    sigismember(&set, SIGINT)) {
> +		sigend(SIGTERM);
> +		ret = true;
> +	}
> +	if (sigismember(&set, SIGHUP))
> +		sighup(SIGHUP);
> +	if (sigismember(&set, SIGUSR1))
> +		sigusr1(SIGUSR1);
> +	if (sigismember(&set, SIGUSR2))
> +		sigusr2(SIGUSR2);
> +
> +	handle_signals(false);
> +	return ret;
> +}
> +
>  static void
>  setscheduler (void)
>  {
> diff --git a/multipathd/main.h b/multipathd/main.h
> index 8fd426b0..2b77b44b 100644
> --- a/multipathd/main.h
> +++ b/multipathd/main.h
> @@ -39,6 +39,7 @@ void * mpath_pr_event_handler_fn (void * );
>  int update_map_pr(struct multipath *mpp);
>  void * mpath_pr_event_handler_fn (void * pathp );
>  void handle_signals(bool);
> +bool deliver_pending_signals(void);
>  int __setup_multipath (struct vectors * vecs, struct multipath * mpp,
>  		       int reset);
>  #define setup_multipath(vecs, mpp) __setup_multipath(vecs, mpp, 1)
> -- 
> 2.19.2