[PATCH] Fix ETIME handling for Solaris event ports

[Jeremy Allison]

On Wed, Feb 03, 2016 at 03:24:48PM -0700, Nathan Huff wrote:
> Turns out EINTR is even more messed up than ETIME.  It is possible to not
> get an event and not have nget updated either so you have to actually check
> the event structure you get back.  I have attached an updated patch to deal
> with that situation as well.

Reviewed-by: Jeremy Allison <jra at samba.org>

Nice work Nathan, good catch.

Can I get a second Team reviewer ?

> From c7790ac220217e4d6c03750e11eb2c03ace4df83 Mon Sep 17 00:00:00 2001
> From: Nathan Huff <nhuff at acm.org>
> Date: Wed, 3 Feb 2016 13:06:52 -0700
> Subject: [PATCH] Handle ETIME and EINTR handling for solaris event ports.
> 
> It is quite possible to get a return of -1 and a errno of ETIME from
> port_getn and also get an event returned. The attached patch checks for
> the number of events returned and if it isn't 0 it falls through to the
> event handling code.
> 
> If you get EINTR back it might be possible that you got an event, but it
> also is possible that you didn't get an event and nget isn't updated so
> you need to check whether the event list was actually filled in. The
> patch sets a port source value that isn't valid in the first event so
> that we can check if the event structure was actually initialized.
> 
> If you don't do this Samba loses file descriptor associations since the
> kernel has dissociated the fd from the event port and Samba doesn't process
> the event and reassociate it.
> 
> Signed-off-by: Nathan Huff <nhuff at acm.org>
> ---
>  lib/tevent/tevent_port.c | 54 ++++++++++++++++++++++++++++--------------------
>  1 file changed, 32 insertions(+), 22 deletions(-)
> 
> diff --git a/lib/tevent/tevent_port.c b/lib/tevent/tevent_port.c
> index 5b487d7..8f7bb8b 100644
> --- a/lib/tevent/tevent_port.c
> +++ b/lib/tevent/tevent_port.c
> @@ -458,6 +458,14 @@ static int port_event_loop(struct port_event_context *port_ev, struct timeval *t
>  	struct timespec ts;
>  	struct tevent_context *ev = port_ev->ev;
>  
> +	/*
> +	 * Set to a known non valid value becuase if port_getn returns
> +	 * EINTR and nget > 0 it may have returned an event or it may
> +	 * have just not updated nget. We need to check if the events
> +	 * list was actually filled in
> +	 */
> +	events[0].portev_source = 0;
> +
>  	if (tvalp) {
>  		ts.tv_sec = tvalp->tv_sec;
>  		ts.tv_nsec = tvalp->tv_usec * 1000;
> @@ -484,29 +492,31 @@ static int port_event_loop(struct port_event_context *port_ev, struct timeval *t
>  	port_errno = errno;
>  	tevent_trace_point_callback(ev, TEVENT_TRACE_AFTER_WAIT);
>  
> -	if (ret == -1 && port_errno == EINTR) {
> -		if (ev->signal_events) {
> -			tevent_common_check_signal(ev);
> -		}
> -		/*
> -		 * If no signal handlers we got an unsolicited
> -		 * signal wakeup. This can happen with epoll
> -		 * too. Just return and ignore.
> -		 */
> -		return 0;
> -	}
> -
> -	if (ret == -1 && port_errno == ETIME && tvalp) {
> -		/* we don't care about a possible delay here */
> -		tevent_common_loop_timer_delay(ev);
> -		return 0;
> -	}
> -
>  	if (ret == -1) {
> -		tevent_debug(ev, TEVENT_DEBUG_ERROR,
> -				"port_get failed (%s)\n",
> -				strerror(errno));
> -		return -1;
> +		if (port_errno == EINTR) {
> +			if (events[0].portev_source == 0) {
> +				if (ev->signal_events) {
> +					tevent_common_check_signal(ev);
> +				}
> +				/*
> +				 * If no signal handlers we got an unsolicited
> +				 * signal wakeup. This can happen with epoll
> +				 * too. Just return and ignore.
> +				 */
> +				return 0;
> +			}
> +		} else if (port_errno == ETIME) {
> +			if (nget == 0 && tvalp) {
> +				/* we don't care about a possible delay here */
> +				tevent_common_loop_timer_delay(ev);
> +				return 0;
> +			}
> +		} else {
> +			tevent_debug(ev, TEVENT_DEBUG_ERROR,
> +					"port_get failed (%s)\n",
> +					strerror(errno));
> +			return -1;
> +		}
>  	}
>  
>  	for (i = 0; i < nget; i++) {
> -- 
> 2.5.0
>