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| author |   Jens Axboe <axboe@kernel.dk> | 2020-07-04 08:55:50 -0600 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2020-07-04 13:44:45 -0600 |
| commit | b7db41c9e03b5189bc94993bd50e4506ac9e34c1 (patch) | |
| tree | 66de3253898e9fc1128e7c7e7ed326bfd378ff9b | |
| parent | io_uring: use signal based task_work running (diff) | |
| download | linux-dev-b7db41c9e03b5189bc94993bd50e4506ac9e34c1.tar.xz linux-dev-b7db41c9e03b5189bc94993bd50e4506ac9e34c1.zip | |
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>
| -rw-r--r-- | fs/io_uring.c | 29 |
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(¤t->sighand->siglock); + current->jobctl &= ~JOBCTL_TASK_WORK; + recalc_sigpending(); + spin_unlock_irq(¤t->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; } |