The patch titled
Subject: epoll: loosen irq safety in ep_poll_callback()
has been added to the -mm tree. Its filename is
epoll-loosen-irq-safety-in-ep_poll_callback.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/epoll-loosen-irq-safety-in-ep_poll_callback.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/epoll-loosen-irq-safety-in-ep_poll_callback.patch
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------------------------------------------------------
From: Roman Penyaev <rpenyaev@xxxxxxx>
Subject: epoll: loosen irq safety in ep_poll_callback()
Callers of the ep_poll_callback() (all set of wake_up_*poll()) disable
interrupts, so no need to save/restore irq flags.
Link: http://lkml.kernel.org/r/20190103150104.17128-3-rpenyaev@xxxxxxx
Signed-off-by: Roman Penyaev <rpenyaev@xxxxxxx>
Reviewed-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Davidlohr Bueso <dbueso@xxxxxxx>
Cc: Jason Baron <jbaron@xxxxxxxxxx>
Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: "Paul E. McKenney" <paulmck@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/eventpoll.c | 11 ++++++++---
1 file changed, 8 insertions(+), 3 deletions(-)
--- a/fs/eventpoll.c~epoll-loosen-irq-safety-in-ep_poll_callback
+++ a/fs/eventpoll.c
@@ -1124,13 +1124,18 @@ struct file *get_epoll_tfile_raw_ptr(str
static int ep_poll_callback(wait_queue_entry_t *wait, unsigned mode, int sync, void *key)
{
int pwake = 0;
- unsigned long flags;
struct epitem *epi = ep_item_from_wait(wait);
struct eventpoll *ep = epi->ep;
__poll_t pollflags = key_to_poll(key);
int ewake = 0;
- spin_lock_irqsave(&ep->wq.lock, flags);
+ /*
+ * Called by irq context or interrupts are disabled by the wake_up_*poll
+ * callers.
+ */
+ lockdep_assert_irqs_disabled();
+
+ spin_lock(&ep->wq.lock);
ep_set_busy_poll_napi_id(epi);
@@ -1207,7 +1212,7 @@ static int ep_poll_callback(wait_queue_e
pwake++;
out_unlock:
- spin_unlock_irqrestore(&ep->wq.lock, flags);
+ spin_unlock(&ep->wq.lock);
/* We have to call this outside the lock */
if (pwake)
_
Patches currently in -mm which might be from rpenyaev@xxxxxxx are
epoll-make-sure-all-elements-in-ready-list-are-in-fifo-order.patch
epoll-loosen-irq-safety-in-ep_poll_callback.patch
epoll-unify-awaking-of-wakeup-source-on-ep_poll_callback-path.patch
epoll-use-rwlock-in-order-to-reduce-ep_poll_callback-contention.patch
