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authorLinus Torvalds <torvalds@linux-foundation.org>2020-07-02 14:56:22 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2020-07-02 14:56:22 -0700
commitc93493b7cd40c20708e3373a7cc8e8049460d7ce (patch)
tree72e472420baacf2168d484bbeaf521423115c049 /fs
parentcd77006e01b3198c75fb7819b3d0ff89709539bb (diff)
parentce593a6c480a22acba08795be313c0c6d49dd35d (diff)
downloadlinux-c93493b7cd40c20708e3373a7cc8e8049460d7ce.tar.bz2
Merge tag 'io_uring-5.8-2020-07-01' of git://git.kernel.dk/linux-block
Pull io_uring fixes from Jens Axboe: "One fix in here, for a regression in 5.7 where a task is waiting in the kernel for a condition, but that condition won't become true until task_work is run. And the task_work can't be run exactly because the task is waiting in the kernel, so we'll never make any progress. One example of that is registering an eventfd and queueing io_uring work, and then the task goes and waits in eventfd read with the expectation that it'll get woken (and read an event) when the io_uring request completes. The io_uring request is finished through task_work, which won't get run while the task is looping in eventfd read" * tag 'io_uring-5.8-2020-07-01' of git://git.kernel.dk/linux-block: io_uring: use signal based task_work running task_work: teach task_work_add() to do signal_wake_up()
Diffstat (limited to 'fs')
-rw-r--r--fs/io_uring.c32
1 files changed, 24 insertions, 8 deletions
diff --git a/fs/io_uring.c b/fs/io_uring.c
index e507737f044e..700644a016a7 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -4072,6 +4072,21 @@ struct io_poll_table {
int error;
};
+static int io_req_task_work_add(struct io_kiocb *req, struct callback_head *cb,
+ int notify)
+{
+ struct task_struct *tsk = req->task;
+ int ret;
+
+ if (req->ctx->flags & IORING_SETUP_SQPOLL)
+ notify = 0;
+
+ ret = task_work_add(tsk, cb, notify);
+ if (!ret)
+ wake_up_process(tsk);
+ return ret;
+}
+
static int __io_async_wake(struct io_kiocb *req, struct io_poll_iocb *poll,
__poll_t mask, task_work_func_t func)
{
@@ -4095,13 +4110,13 @@ 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 = task_work_add(tsk, &req->task_work, true);
+ ret = io_req_task_work_add(req, &req->task_work, TWA_SIGNAL);
if (unlikely(ret)) {
WRITE_ONCE(poll->canceled, true);
tsk = io_wq_get_task(req->ctx->io_wq);
- task_work_add(tsk, &req->task_work, true);
+ task_work_add(tsk, &req->task_work, 0);
+ wake_up_process(tsk);
}
- wake_up_process(tsk);
return 1;
}
@@ -6182,19 +6197,20 @@ static int io_cqring_wait(struct io_ring_ctx *ctx, int min_events,
do {
prepare_to_wait_exclusive(&ctx->wait, &iowq.wq,
TASK_INTERRUPTIBLE);
+ /* make sure we run task_work before checking for signals */
if (current->task_works)
task_work_run();
- if (io_should_wake(&iowq, false))
- break;
- schedule();
if (signal_pending(current)) {
- ret = -EINTR;
+ ret = -ERESTARTSYS;
break;
}
+ if (io_should_wake(&iowq, false))
+ break;
+ schedule();
} while (1);
finish_wait(&ctx->wait, &iowq.wq);
- restore_saved_sigmask_unless(ret == -EINTR);
+ restore_saved_sigmask_unless(ret == -ERESTARTSYS);
return READ_ONCE(rings->cq.head) == READ_ONCE(rings->cq.tail) ? ret : 0;
}