Re: [PATCH] gssd: unblock DNOTIFY_SIGNAL in case it was blocked.

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Hi Neil,
I inherited the signal stuff, so my understanding probably isn't any
better than yours.  I won't be able to look closer at this until
Wednesday.  Meanwhile, maybe someone else has a better understanding.

K.C.

On Mon, Nov 10, 2008 at 5:29 PM, Neil Brown <neilb@xxxxxxx> wrote:
>
> I have a situation where rpc.gssd appears to not be working.
> Mount attempts which need to communicate with it block.
>
> I've narrowed down the problem to that fact that all realtime signals
> have been blocked.  This means that DNOTIFY_SIGNAL (which is a
> realtime signal) is never delivered, so gssd never rescans the
> rpc_pipe/nfs directory.
>
> I haven't figured out why the signals are blocked yet, but having
> rpc.gssd fail mysteriously in that situation isn't pleasant.
>
> So I wonder what people think of the following patch.  It simply
> unblocks the signal.  Alternately we can check if it is blocked and
> warn - I'm not really sure of the significance of blocking all these
> signals.  Maybe it's wrong to just unblock them.
>
>
> As an aside, maybe we could change gssd_run to use "ppoll" rather than
> "poll".  Then it would not have to wake up every 500msec to see if it
> missed a signal. We would probably have to check kernel version was at
> least 2.6.16....
>
> NeilBrown
>
>
>
> diff --git a/utils/gssd/gssd_main_loop.c b/utils/gssd/gssd_main_loop.c
> index 84f04e9..b9f3a06 100644
> --- a/utils/gssd/gssd_main_loop.c
> +++ b/utils/gssd/gssd_main_loop.c
> @@ -99,6 +99,7 @@ gssd_run()
>        int                     ret;
>        struct sigaction        dn_act;
>        int                     fd;
> +       sigset_t                set;
>
>        /* Taken from linux/Documentation/dnotify.txt: */
>        dn_act.sa_sigaction = dir_notify_handler;
> @@ -106,6 +107,11 @@ gssd_run()
>        dn_act.sa_flags = SA_SIGINFO;
>        sigaction(DNOTIFY_SIGNAL, &dn_act, NULL);
>
> +       /* just in case the signal is blocked... */
> +       sigemptyset(&set);
> +       sigaddset(&set, DNOTIFY_SIGNAL);
> +       sigprocmask(SIG_UNBLOCK, &set, NULL);
> +
>        if ((fd = open(pipefs_nfsdir, O_RDONLY)) == -1) {
>                printerr(0, "ERROR: failed to open %s: %s\n",
>                         pipefs_nfsdir, strerror(errno));
>
>
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