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io-wq: improve manager/worker handling over exec

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exec will cancel any threads, including the ones that io-wq is using. This
isn't a problem, in fact we'd prefer it to be that way since it means we
know that any async work cancels naturally without having to handle it
proactively.

But it does mean that we need to setup a new manager, as the manager and
workers are gone. Handle this at queue time, and cancel work if we fail.
Since the manager can go away without us noticing, ensure that the manager
itself holds a reference to the 'wq' as well. Rename io_wq_destroy() to
io_wq_put() to reflect that.

In the future we can now simplify exec cancelation handling, for now just
leave it the same.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Jens Axboe
2021-02-25 10:17:09 -07:00
parent eb85890b29
commit 4fb6ac3262
3 changed files with 45 additions and 23 deletions
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4
fs/io_uring.c
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@@ -2024,7 +2024,7 @@ 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);
if (!ctx->sqo_dead && !(current->flags & PF_EXITING))
if (!ctx->sqo_dead && !(current->flags & PF_EXITING) && !current->in_execve)
__io_queue_sqe(req);
else
__io_req_task_cancel(req, -EFAULT);
@@ -8821,7 +8821,7 @@ void __io_uring_files_cancel(struct files_struct *files)
if (files) {
io_uring_remove_task_files(tctx);
if (tctx->io_wq) {
io_wq_destroy(tctx->io_wq);
io_wq_put(tctx->io_wq);
tctx->io_wq = NULL;
}
}