@@ -61,7 +61,7 @@ struct userfaultfd_ctx {
/* waitqueue head for events */
wait_queue_head_t event_wqh;
/* a refile sequence protected by fault_pending_wqh lock */
- struct seqcount refile_seq;
+ seqcount_spinlock_t refile_seq;
/* pseudo fd refcounting */
refcount_t refcount;
/* userfaultfd syscall flags */
@@ -1998,7 +1998,7 @@ static void init_once_userfaultfd_ctx(void *mem)
init_waitqueue_head(&ctx->fault_wqh);
init_waitqueue_head(&ctx->event_wqh);
init_waitqueue_head(&ctx->fd_wqh);
- seqcount_init(&ctx->refile_seq);
+ seqcount_spinlock_init(&ctx->refile_seq, &ctx->fault_pending_wqh.lock);
}
SYSCALL_DEFINE1(userfaultfd, int, flags)
A sequence counter write side critical section must be protected by some form of locking to serialize writers. A plain seqcount_t does not contain the information of which lock must be held when entering a write side critical section. Use the new seqcount_spinlock_t data type, which allows to associate a spinlock with the sequence counter. This enables lockdep to verify that the spinlock used for writer serialization is held when the write side critical section is entered. If lockdep is disabled this lock association is compiled out and has neither storage size nor runtime overhead. Signed-off-by: Ahmed S. Darwish <a.darwish@linutronix.de> --- fs/userfaultfd.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)