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Diffstat (limited to 'io_uring/poll.c')
-rw-r--r--io_uring/poll.c14
1 files changed, 12 insertions, 2 deletions
diff --git a/io_uring/poll.c b/io_uring/poll.c
index 8339a92b4510..a82d6830bdfd 100644
--- a/io_uring/poll.c
+++ b/io_uring/poll.c
@@ -650,6 +650,14 @@ static void io_async_queue_proc(struct file *file, struct wait_queue_head *head,
__io_queue_proc(&apoll->poll, pt, head, &apoll->double_poll);
}
+/*
+ * We can't reliably detect loops in repeated poll triggers and issue
+ * subsequently failing. But rather than fail these immediately, allow a
+ * certain amount of retries before we give up. Given that this condition
+ * should _rarely_ trigger even once, we should be fine with a larger value.
+ */
+#define APOLL_MAX_RETRY 128
+
static struct async_poll *io_req_alloc_apoll(struct io_kiocb *req,
unsigned issue_flags)
{
@@ -665,14 +673,18 @@ static struct async_poll *io_req_alloc_apoll(struct io_kiocb *req,
if (entry == NULL)
goto alloc_apoll;
apoll = container_of(entry, struct async_poll, cache);
+ apoll->poll.retries = APOLL_MAX_RETRY;
} else {
alloc_apoll:
apoll = kmalloc(sizeof(*apoll), GFP_ATOMIC);
if (unlikely(!apoll))
return NULL;
+ apoll->poll.retries = APOLL_MAX_RETRY;
}
apoll->double_poll = NULL;
req->apoll = apoll;
+ if (unlikely(!--apoll->poll.retries))
+ return NULL;
return apoll;
}
@@ -694,8 +706,6 @@ int io_arm_poll_handler(struct io_kiocb *req, unsigned issue_flags)
return IO_APOLL_ABORTED;
if (!file_can_poll(req->file))
return IO_APOLL_ABORTED;
- if ((req->flags & (REQ_F_POLLED|REQ_F_PARTIAL_IO)) == REQ_F_POLLED)
- return IO_APOLL_ABORTED;
if (!(req->flags & REQ_F_APOLL_MULTISHOT))
mask |= EPOLLONESHOT;