From: Paolo Bonzini <pbonzini@redhat.com>
To: Emanuele Giuseppe Esposito <eesposit@redhat.com>, qemu-block@nongnu.org
Cc: Kevin Wolf <kwolf@redhat.com>,
qemu-devel@nongnu.org, Max Reitz <mreitz@redhat.com>
Subject: Re: [PATCH 4/5] blkdebug: do not suspend in the middle of QLIST_FOREACH_SAFE
Date: Tue, 13 Apr 2021 09:48:56 +0200 [thread overview]
Message-ID: <6545bc04-87d9-2ba7-9b57-8a4488493875@redhat.com> (raw)
In-Reply-To: <20210408155913.53235-5-eesposit@redhat.com>
On 08/04/21 17:59, Emanuele Giuseppe Esposito wrote:
Perhaps insert here:
That would be unsafe in case a rule other than the current one is
removed while the coroutine has yielded. Keep FOREACH_SAFE because
suspend_request deletes the current rule.
After this patch, *all* matching rules are deleted before suspending the
coroutine, rather than just one. This doesn't affect the existing
testcases.
> Use actions_count to see how many yeld to issue.
>
> Co-developed-by: Paolo Bonzini <pbonzini@redhat.com>
> Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
> ---
> block/blkdebug.c | 7 ++++++-
> 1 file changed, 6 insertions(+), 1 deletion(-)
>
> diff --git a/block/blkdebug.c b/block/blkdebug.c
> index 388b5ed615..dffd869b32 100644
> --- a/block/blkdebug.c
> +++ b/block/blkdebug.c
> @@ -789,7 +789,6 @@ static void suspend_request(BlockDriverState *bs, BlkdebugRule *rule)
> if (!qtest_enabled()) {
> printf("blkdebug: Suspended request '%s'\n", r->tag);
> }
> - qemu_coroutine_yield();
> }
>
> static void process_rule(BlockDriverState *bs, struct BlkdebugRule *rule,
> @@ -834,6 +833,12 @@ static void blkdebug_debug_event(BlockDriverState *bs, BlkdebugEvent event)
> QLIST_FOREACH_SAFE(rule, &s->rules[event], next, next) {
> process_rule(bs, rule, actions_count);
> }
> +
> + while (actions_count[ACTION_SUSPEND] > 0) {
> + qemu_coroutine_yield();
> + actions_count[ACTION_SUSPEND]--;
> + }
> +
> s->state = s->new_state;
> }
>
>
next prev parent reply other threads:[~2021-04-13 7:50 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-08 15:59 [PATCH 0/5] blkdebug: fix racing condition when iterating on Emanuele Giuseppe Esposito
2021-04-08 15:59 ` [PATCH 1/5] blkdebug: refactor removal of a suspended request Emanuele Giuseppe Esposito
2021-04-08 15:59 ` [PATCH 2/5] blkdebug: move post-resume handling to resume_req_by_tag Emanuele Giuseppe Esposito
2021-04-08 15:59 ` [PATCH 3/5] blkdebug: track all actions Emanuele Giuseppe Esposito
2021-04-08 15:59 ` [PATCH 4/5] blkdebug: do not suspend in the middle of QLIST_FOREACH_SAFE Emanuele Giuseppe Esposito
2021-04-13 7:48 ` Paolo Bonzini [this message]
2021-04-08 15:59 ` [PATCH 5/5] blkdebug: protect rules and suspended_reqs with a lock Emanuele Giuseppe Esposito
2021-04-13 7:50 ` [PATCH 0/5] blkdebug: fix racing condition when iterating on Paolo Bonzini
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