At Mon, 17 Feb 2014 17:12:18 +0900, Hitoshi Mitake wrote: > > Current main event loop (event_loop()) of tgtd has a possibility of > segmentation fault. The problem is caused by the below sequence: > > 1. Event A, B are ready so epoll_wait(2) returns. > 2. The handler of the event A is called. In the event handler, the > event B is deleted with tgt_event_del() > 3. event_loop() tries to call the handler of the event B. It causes > segfault because the event struct is already removed and freed. > > For avoid this problem, this patch adds a new global variable > event_need_refresh. If the value of this variable is 1, event_loop() > calls epoll_wait(2) again for refreshing ready fd list. This patch > also lets tgt_event_del() to turn on the flag in its tail. With this > modification, the above segfault is avoided. > > Signed-off-by: Hitoshi Mitake <mitake.hitoshi@xxxxxxxxxxxxx> > --- > usr/tgtd.c | 10 ++++++++++ > usr/tgtd.h | 2 ++ > 2 files changed, 12 insertions(+) I found a little problem in this patch. I'll send v2 soon. Thanks, Hitoshi > > diff --git a/usr/tgtd.c b/usr/tgtd.c > index 09c1442..c758458 100644 > --- a/usr/tgtd.c > +++ b/usr/tgtd.c > @@ -215,6 +215,8 @@ static struct event_data *tgt_event_lookup(int fd) > return NULL; > } > > +int event_need_refresh; > + > void tgt_event_del(int fd) > { > struct event_data *tev; > @@ -232,6 +234,8 @@ void tgt_event_del(int fd) > > list_del(&tev->e_list); > free(tev); > + > + event_need_refresh = 1; > } > > int tgt_event_modify(int fd, int events) > @@ -419,6 +423,7 @@ retry: > sched_remains = tgt_exec_scheduled(); > timeout = sched_remains ? 0 : -1; > > +refresh: > nevent = epoll_wait(ep_fd, events, ARRAY_SIZE(events), timeout); > if (nevent < 0) { > if (errno != EINTR) { > @@ -429,6 +434,11 @@ retry: > for (i = 0; i < nevent; i++) { > tev = (struct event_data *) events[i].data.ptr; > tev->handler(tev->fd, events[i].events, tev->data); > + > + if (event_need_refresh) { > + event_need_refresh = 0; > + goto refresh; > + } > } > } > > diff --git a/usr/tgtd.h b/usr/tgtd.h > index a708f13..91dd7b4 100644 > --- a/usr/tgtd.h > +++ b/usr/tgtd.h > @@ -406,4 +406,6 @@ struct service_action * > find_service_action(struct service_action *service_action, > uint32_t action); > > +extern int event_need_refresh; > + > #endif > -- > 1.7.10.4 > -- To unsubscribe from this list: send the line "unsubscribe stgt" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html