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[Qemu-commits] [qemu/qemu] cf4fbc: block/nvme: fix infinite loop in nvme
From: |
Richard Henderson |
Subject: |
[Qemu-commits] [qemu/qemu] cf4fbc: block/nvme: fix infinite loop in nvme_free_req_que... |
Date: |
Tue, 14 Dec 2021 14:36:42 -0800 |
Branch: refs/heads/master
Home: https://github.com/qemu/qemu
Commit: cf4fbc3030c974fff726756a7ceef8386cdf500b
https://github.com/qemu/qemu/commit/cf4fbc3030c974fff726756a7ceef8386cdf500b
Author: Stefan Hajnoczi <stefanha@redhat.com>
Date: 2021-12-09 (Thu, 09 Dec 2021)
Changed paths:
M block/nvme.c
Log Message:
-----------
block/nvme: fix infinite loop in nvme_free_req_queue_cb()
When the request free list is exhausted the coroutine waits on
q->free_req_queue for the next free request. Whenever a request is
completed a BH is scheduled to invoke nvme_free_req_queue_cb() and wake
up waiting coroutines.
1. nvme_get_free_req() waits for a free request:
while (q->free_req_head == -1) {
...
trace_nvme_free_req_queue_wait(q->s, q->index);
qemu_co_queue_wait(&q->free_req_queue, &q->lock);
...
}
2. nvme_free_req_queue_cb() wakes up the coroutine:
while (qemu_co_enter_next(&q->free_req_queue, &q->lock)) {
^--- infinite loop when free_req_head == -1
}
nvme_free_req_queue_cb() and the coroutine form an infinite loop when
q->free_req_head == -1. Fix this by checking q->free_req_head in
nvme_free_req_queue_cb(). If the free request list is exhausted, don't
wake waiting coroutines. Eventually an in-flight request will complete
and the BH will be scheduled again, guaranteeing forward progress.
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-id: 20211208152246.244585-1-stefanha@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Commit: 76b56fdfc9fa43ec6e5986aee33f108c6c6a511e
https://github.com/qemu/qemu/commit/76b56fdfc9fa43ec6e5986aee33f108c6c6a511e
Author: Richard Henderson <richard.henderson@linaro.org>
Date: 2021-12-14 (Tue, 14 Dec 2021)
Changed paths:
M block/nvme.c
Log Message:
-----------
Merge tag 'block-pull-request' of https://gitlab.com/stefanha/qemu into
staging
Pull request
An infinite loop fix for the userspace NVMe driver.
# gpg: Signature made Thu 09 Dec 2021 07:21:08 AM PST
# gpg: using RSA key 8695A8BFD3F97CDAAC35775A9CA4ABB381AB73C8
# gpg: Good signature from "Stefan Hajnoczi <stefanha@redhat.com>" [full]
# gpg: aka "Stefan Hajnoczi <stefanha@gmail.com>" [full]
* tag 'block-pull-request' of https://gitlab.com/stefanha/qemu:
block/nvme: fix infinite loop in nvme_free_req_queue_cb()
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Compare: https://github.com/qemu/qemu/compare/af1719795c88...76b56fdfc9fa
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