Events: protection from stale events in eventport and devpoll.

Stale write event may happen if read and write events was reported both,
and processing of the read event closed descriptor.

In practice this might result in "sendfilev() failed (134: ..." or
"writev() failed (134: ..." errors when switching to next upstream server.

See report here:
http://mailman.nginx.org/pipermail/nginx/2013-April/038421.html

diff --git a/src/event/modules/ngx_devpoll_module.c b/src/event/modules/ngx_devpoll_module.c
index d09b5bc07adc9773445e7d28d9685a46923fa43a..5f78cd7d32204c6e0b9d2d16deba2091742534ae 100644 (file)
--- a/src/event/modules/ngx_devpoll_module.c
+++ b/src/event/modules/ngx_devpoll_module.c
@@ -343,7 +343,7 @@ ngx_devpoll_process_events(ngx_cycle_t *cycle, ngx_msec_t timer,
     ngx_fd_t            fd;
     ngx_err_t           err;
     ngx_int_t           i;
-    ngx_uint_t          level;
+    ngx_uint_t          level, instance;
     ngx_event_t        *rev, *wev, **queue;
     ngx_connection_t   *c;
     struct pollfd       pfd;
@@ -510,7 +510,13 @@ ngx_devpoll_process_events(ngx_cycle_t *cycle, ngx_msec_t timer,
                 ngx_locked_post_event(rev, queue);
 
             } else {
+                instance = rev->instance;
+
                 rev->handler(rev);
+
+                if (c->fd == -1 || wev->instance != instance) {
+                    continue;
+                }
             }
         }
 

diff --git a/src/event/modules/ngx_eventport_module.c b/src/event/modules/ngx_eventport_module.c
index d6dcb0bedf4cbb8cb4ae87f52fd1af35b597f89c..5f9cf4e35fbabacfa020436b52d867b2544523f6 100644 (file)
--- a/src/event/modules/ngx_eventport_module.c
+++ b/src/event/modules/ngx_eventport_module.c
@@ -551,7 +551,7 @@ ngx_eventport_process_events(ngx_cycle_t *cycle, ngx_msec_t timer,
                 } else {
                     rev->handler(rev);
 
-                    if (ev->closed) {
+                    if (ev->closed || ev->instance != instance) {
                         continue;
                     }
                 }