diff options
| -rw-r--r-- | fs/eventpoll.c | 20 |
1 files changed, 19 insertions, 1 deletions
diff --git a/fs/eventpoll.c b/fs/eventpoll.c index baa97d0edade..df364a8783b5 100644 --- a/fs/eventpoll.c +++ b/fs/eventpoll.c @@ -38,6 +38,7 @@ #include <linux/compat.h> #include <linux/rculist.h> #include <linux/capability.h> +#include <linux/seqlock.h> #include <net/busy_poll.h> /* @@ -312,6 +313,9 @@ struct eventpoll { /* Lock which protects rdllist and ovflist */ spinlock_t lock; + /* Protect switching between rdllist and ovflist */ + seqcount_spinlock_t seq; + /* RB tree root used to store monitored fd structs */ struct rb_root_cached rbr; @@ -590,7 +594,10 @@ static inline void epi_clear_ovflist(struct epitem *epi) /* True iff @ep has ready events that epoll_wait() might harvest. */ static inline bool ep_events_available(struct eventpoll *ep) { - return !list_empty_careful(&ep->rdllist) || ep_is_scanning(ep); + unsigned int seq = read_seqcount_begin(&ep->seq); + + return !list_empty_careful(&ep->rdllist) || ep_is_scanning(ep) || + read_seqcount_retry(&ep->seq, seq); } #ifdef CONFIG_NET_RX_BUSY_POLL @@ -947,8 +954,12 @@ static void ep_start_scan(struct eventpoll *ep, struct list_head *scan_batch) */ lockdep_assert_irqs_enabled(); spin_lock_irq(&ep->lock); + write_seqcount_begin(&ep->seq); + list_splice_init(&ep->rdllist, scan_batch); ep_enter_scan(ep); + + write_seqcount_end(&ep->seq); spin_unlock_irq(&ep->lock); } @@ -979,6 +990,9 @@ static void ep_done_scan(struct eventpoll *ep, ep_pm_stay_awake(epi); } } + + write_seqcount_begin(&ep->seq); + /* Back out of scan mode; callbacks target ep->rdllist again. */ ep_exit_scan(ep); @@ -986,6 +1000,9 @@ static void ep_done_scan(struct eventpoll *ep, * Quickly re-inject items left on "scan_batch". */ list_splice(scan_batch, &ep->rdllist); + + write_seqcount_end(&ep->seq); + __pm_relax(ep->ws); if (!list_empty(&ep->rdllist)) { @@ -1405,6 +1422,7 @@ static int ep_alloc(struct eventpoll **pep) mutex_init(&ep->mtx); spin_lock_init(&ep->lock); + seqcount_spinlock_init(&ep->seq, &ep->lock); init_waitqueue_head(&ep->wq); init_waitqueue_head(&ep->poll_wait); INIT_LIST_HEAD(&ep->rdllist); |