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| author | Jens Axboe <axboe@kernel.dk> | 2021-08-19 09:41:42 -0600 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2021-08-23 13:10:43 -0600 |
| commit | 316319e82f7342ef327223a23199648bfabeadcd (patch) | |
| tree | 9815be0817acb9c61cef211be806f7ea4d611041 /fs/io_uring.c | |
| parent | 79dca1846fe979304ad0b998e56b20326e2e5a72 (diff) | |
| download | lwn-316319e82f7342ef327223a23199648bfabeadcd.tar.gz lwn-316319e82f7342ef327223a23199648bfabeadcd.zip | |
io_uring: add comments on why PF_EXITING checking is safe
We have two checks of task->flags & PF_EXITING left:
1) In io_req_task_submit(), which is called in task_work and hence always
in the context of the original task. That means that
req->task == current, and hence checking ->flags is totally fine.
2) In io_poll_rewait(), where we need to stop re-arming poll to prevent
it interfering with cancelation. This is only run from task_work as
well, and hence for this case too req->task == current.
Add a comment to both spots detailing that.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'fs/io_uring.c')
| -rw-r--r-- | fs/io_uring.c | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/fs/io_uring.c b/fs/io_uring.c index 08546332f1b9..78aa4daf7969 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -2112,6 +2112,7 @@ static void io_req_task_submit(struct io_kiocb *req) /* ctx stays valid until unlock, even if we drop all ours ctx->refs */ mutex_lock(&ctx->uring_lock); + /* req->task == current here, checking PF_EXITING is safe */ if (likely(!(req->task->flags & PF_EXITING))) __io_queue_sqe(req); else @@ -4893,6 +4894,7 @@ static bool io_poll_rewait(struct io_kiocb *req, struct io_poll_iocb *poll) { struct io_ring_ctx *ctx = req->ctx; + /* req->task == current here, checking PF_EXITING is safe */ if (unlikely(req->task->flags & PF_EXITING)) WRITE_ONCE(poll->canceled, true); |