From: Martin Karsten mkarsten@uwaterloo.ca

A struct eventpoll's busy_poll_usecs field can be modified via a user ioctl at any time. All reads of this field should be annotated with READ_ONCE.

Fixes: 85455c795c07 ("eventpoll: support busy poll per epoll instance") Cc: stable@vger.kernel.org Signed-off-by: Martin Karsten mkarsten@uwaterloo.ca Reviewed-by: Joe Damato jdamato@fastly.com --- fs/eventpoll.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/eventpoll.c b/fs/eventpoll.c index f53ca4f7fced..6d0e2f547ae7 100644 --- a/fs/eventpoll.c +++ b/fs/eventpoll.c @@ -420,7 +420,7 @@ static bool busy_loop_ep_timeout(unsigned long start_time,

static bool ep_busy_loop_on(struct eventpoll *ep) { - return !!ep->busy_poll_usecs || net_busy_loop_on(); + return !!READ_ONCE(ep->busy_poll_usecs) || net_busy_loop_on(); }

static bool ep_busy_loop_end(void *p, unsigned long start_time)