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Fix bug in epoll_ctl() usage causing blocked connections (#41067)

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(cherry picked from commit 7bc21557f3)
(cherry picked from commit dd2b5cf45b)
This commit is contained in:
Mukund Sivaraman 2015-11-19 11:01:45 +05:30
parent 603bef1c44
commit 4452ce8b4f
2 changed files with 69 additions and 8 deletions
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7
CHANGES
View file

@ -1,3 +1,10 @@
4262. [bug] Fixed a bug in epoll socket code that caused
sockets to not be registered for ready
notification in some cases, causing named to not
read from or write to them, resulting in what
appear to the user as blocked connections.
[RT #41067]
4261. [maint] H.ROOT-SERVERS.NET is 198.97.190.53 and 2001:500:1::53.
[RT #40556]

70
lib/isc/unix/socket.c
View file

@ -394,6 +394,9 @@ struct isc__socketmgr {
/* Locked by fdlock. */
isc__socket_t **fds;
int *fdstate;
#if defined(USE_EPOLL)
uint32_t *epoll_events;
#endif
#ifdef USE_DEVPOLL
pollinfo_t *fdpollinfo;
#endif
@ -835,15 +838,27 @@ watch_fd(isc__socketmgr_t *manager, int fd, int msg) {
return (result);
#elif defined(USE_EPOLL)
struct epoll_event event;
uint32_t oldevents;
int ret;
int op;
oldevents = manager->epoll_events[fd];
if (msg == SELECT_POKE_READ)
event.events = EPOLLIN;
manager->epoll_events[fd] |= EPOLLIN;
else
event.events = EPOLLOUT;
manager->epoll_events[fd] |= EPOLLOUT;
event.events = manager->epoll_events[fd];
memset(&event.data, 0, sizeof(event.data));
event.data.fd = fd;
if (epoll_ctl(manager->epoll_fd, EPOLL_CTL_ADD, fd, &event) == -1 &&
errno != EEXIST) {
op = (oldevents == 0U) ? EPOLL_CTL_ADD : EPOLL_CTL_MOD;
ret = epoll_ctl(manager->epoll_fd, op, fd, &event);
if (ret == -1) {
if (errno == EEXIST)
UNEXPECTED_ERROR(__FILE__, __LINE__,
"epoll_ctl(ADD/MOD) returned "
"EEXIST for fd %d", fd);
result = isc__errno2result(errno);
}
@ -903,15 +918,21 @@ unwatch_fd(isc__socketmgr_t *manager, int fd, int msg) {
return (result);
#elif defined(USE_EPOLL)
struct epoll_event event;
int ret;
int op;
if (msg == SELECT_POKE_READ)
event.events = EPOLLIN;
manager->epoll_events[fd] &= ~(EPOLLIN);
else
event.events = EPOLLOUT;
manager->epoll_events[fd] &= ~(EPOLLOUT);
event.events = manager->epoll_events[fd];
memset(&event.data, 0, sizeof(event.data));
event.data.fd = fd;
if (epoll_ctl(manager->epoll_fd, EPOLL_CTL_DEL, fd, &event) == -1 &&
errno != ENOENT) {
op = (event.events == 0U) ? EPOLL_CTL_DEL : EPOLL_CTL_MOD;
ret = epoll_ctl(manager->epoll_fd, op, fd, &event);
if (ret == -1 && errno != ENOENT) {
char strbuf[ISC_STRERRORSIZE];
isc__strerror(errno, strbuf, sizeof(strbuf));
UNEXPECTED_ERROR(__FILE__, __LINE__,
@ -2640,6 +2661,9 @@ socket_create(isc_socketmgr_t *manager0, int pf, isc_sockettype_t type,
LOCK(&manager->fdlock[lockid]);
manager->fds[sock->fd] = sock;
manager->fdstate[sock->fd] = MANAGED;
#if defined(USE_EPOLL)
manager->epoll_events[sock->fd] = 0;
#endif
#ifdef USE_DEVPOLL
INSIST(sock->manager->fdpollinfo[sock->fd].want_read == 0 &&
sock->manager->fdpollinfo[sock->fd].want_write == 0);
@ -2717,6 +2741,9 @@ isc__socket_open(isc_socket_t *sock0) {
LOCK(&sock->manager->fdlock[lockid]);
sock->manager->fds[sock->fd] = sock;
sock->manager->fdstate[sock->fd] = MANAGED;
#if defined(USE_EPOLL)
sock->manager->epoll_events[sock->fd] = 0;
#endif
#ifdef USE_DEVPOLL
INSIST(sock->manager->fdpollinfo[sock->fd].want_read == 0 &&
sock->manager->fdpollinfo[sock->fd].want_write == 0);
@ -2778,6 +2805,9 @@ isc__socket_fdwatchcreate(isc_socketmgr_t *manager0, int fd, int flags,
LOCK(&manager->fdlock[lockid]);
manager->fds[sock->fd] = sock;
manager->fdstate[sock->fd] = MANAGED;
#if defined(USE_EPOLL)
manager->epoll_events[sock->fd] = 0;
#endif
UNLOCK(&manager->fdlock[lockid]);
LOCK(&manager->lock);
@ -3317,6 +3347,9 @@ internal_accept(isc_task_t *me, isc_event_t *ev) {
LOCK(&manager->fdlock[lockid]);
manager->fds[fd] = NEWCONNSOCK(dev);
manager->fdstate[fd] = MANAGED;
#if defined(USE_EPOLL)
manager->epoll_events[fd] = 0;
#endif
UNLOCK(&manager->fdlock[lockid]);
LOCK(&manager->lock);
@ -4267,6 +4300,15 @@ isc__socketmgr_create2(isc_mem_t *mctx, isc_socketmgr_t **managerp,
result = ISC_R_NOMEMORY;
goto free_manager;
}
#if defined(USE_EPOLL)
manager->epoll_events = isc_mem_get(mctx, (manager->maxsocks *
sizeof(uint32_t)));
if (manager->epoll_events == NULL) {
result = ISC_R_NOMEMORY;
goto free_manager;
}
memset(manager->epoll_events, 0, manager->maxsocks * sizeof(uint32_t));
#endif
manager->stats = NULL;
manager->common.methods = &socketmgrmethods;
@ -4336,7 +4378,9 @@ isc__socketmgr_create2(isc_mem_t *mctx, isc_socketmgr_t **managerp,
result = setup_watcher(mctx, manager);
if (result != ISC_R_SUCCESS)
goto cleanup;
memset(manager->fdstate, 0, manager->maxsocks * sizeof(int));
#ifdef USE_WATCHER_THREAD
/*
* Start up the select/poll thread.
@ -4385,6 +4429,12 @@ free_manager:
isc_mem_put(mctx, manager->fdlock,
FDLOCK_COUNT * sizeof(isc_mutex_t));
}
#if defined(USE_EPOLL)
if (manager->epoll_events != NULL) {
isc_mem_put(mctx, manager->epoll_events,
manager->maxsocks * sizeof(uint32_t));
}
#endif
if (manager->fdstate != NULL) {
isc_mem_put(mctx, manager->fdstate,
manager->maxsocks * sizeof(int));
@ -4500,6 +4550,10 @@ isc__socketmgr_destroy(isc_socketmgr_t **managerp) {
if (manager->fdstate[i] == CLOSE_PENDING) /* no need to lock */
(void)close(i);
#if defined(USE_EPOLL)
isc_mem_put(manager->mctx, manager->epoll_events,
manager->maxsocks * sizeof(uint32_t));
#endif
isc_mem_put(manager->mctx, manager->fds,
manager->maxsocks * sizeof(isc__socket_t *));
isc_mem_put(manager->mctx, manager->fdstate,