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authorJens Axboe <axboe@kernel.dk>2020-07-04 08:55:50 -0600
committerJens Axboe <axboe@kernel.dk>2020-07-04 13:44:45 -0600
commitb7db41c9e03b5189bc94993bd50e4506ac9e34c1 (patch)
tree66de3253898e9fc1128e7c7e7ed326bfd378ff9b /fs
parentce593a6c480a22acba08795be313c0c6d49dd35d (diff)
downloadlinux-b7db41c9e03b5189bc94993bd50e4506ac9e34c1.tar.bz2
io_uring: fix regression with always ignoring signals in io_cqring_wait()
When switching to TWA_SIGNAL for task_work notifications, we also made any signal based condition in io_cqring_wait() return -ERESTARTSYS. This breaks applications that rely on using signals to abort someone waiting for events. Check if we have a signal pending because of queued task_work, and repeat the signal check once we've run the task_work. This provides a reliable way of telling the two apart. Additionally, only use TWA_SIGNAL if we are using an eventfd. If not, we don't have the dependency situation described in the original commit, and we can get by with just using TWA_RESUME like we previously did. Fixes: ce593a6c480a ("io_uring: use signal based task_work running") Cc: stable@vger.kernel.org # v5.7 Reported-by: Andres Freund <andres@anarazel.de> Tested-by: Andres Freund <andres@anarazel.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'fs')
-rw-r--r--fs/io_uring.c29
1 files changed, 22 insertions, 7 deletions
diff --git a/fs/io_uring.c b/fs/io_uring.c
index 700644a016a7..d37d7ea5ebe5 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -4072,14 +4072,22 @@ struct io_poll_table {
int error;
};
-static int io_req_task_work_add(struct io_kiocb *req, struct callback_head *cb,
- int notify)
+static int io_req_task_work_add(struct io_kiocb *req, struct callback_head *cb)
{
struct task_struct *tsk = req->task;
- int ret;
+ struct io_ring_ctx *ctx = req->ctx;
+ int ret, notify = TWA_RESUME;
- if (req->ctx->flags & IORING_SETUP_SQPOLL)
+ /*
+ * SQPOLL kernel thread doesn't need notification, just a wakeup.
+ * If we're not using an eventfd, then TWA_RESUME is always fine,
+ * as we won't have dependencies between request completions for
+ * other kernel wait conditions.
+ */
+ if (ctx->flags & IORING_SETUP_SQPOLL)
notify = 0;
+ else if (ctx->cq_ev_fd)
+ notify = TWA_SIGNAL;
ret = task_work_add(tsk, cb, notify);
if (!ret)
@@ -4110,7 +4118,7 @@ static int __io_async_wake(struct io_kiocb *req, struct io_poll_iocb *poll,
* of executing it. We can't safely execute it anyway, as we may not
* have the needed state needed for it anyway.
*/
- ret = io_req_task_work_add(req, &req->task_work, TWA_SIGNAL);
+ ret = io_req_task_work_add(req, &req->task_work);
if (unlikely(ret)) {
WRITE_ONCE(poll->canceled, true);
tsk = io_wq_get_task(req->ctx->io_wq);
@@ -6201,7 +6209,14 @@ static int io_cqring_wait(struct io_ring_ctx *ctx, int min_events,
if (current->task_works)
task_work_run();
if (signal_pending(current)) {
- ret = -ERESTARTSYS;
+ if (current->jobctl & JOBCTL_TASK_WORK) {
+ spin_lock_irq(&current->sighand->siglock);
+ current->jobctl &= ~JOBCTL_TASK_WORK;
+ recalc_sigpending();
+ spin_unlock_irq(&current->sighand->siglock);
+ continue;
+ }
+ ret = -EINTR;
break;
}
if (io_should_wake(&iowq, false))
@@ -6210,7 +6225,7 @@ static int io_cqring_wait(struct io_ring_ctx *ctx, int min_events,
} while (1);
finish_wait(&ctx->wait, &iowq.wq);
- restore_saved_sigmask_unless(ret == -ERESTARTSYS);
+ restore_saved_sigmask_unless(ret == -EINTR);
return READ_ONCE(rings->cq.head) == READ_ONCE(rings->cq.tail) ? ret : 0;
}