From: Paolo Bonzini <pbonzini@redhat.com>
To: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>,
Emanuele Giuseppe Esposito <eesposit@redhat.com>,
qemu-block@nongnu.org
Cc: Kevin Wolf <kwolf@redhat.com>, John Snow <jsnow@redhat.com>,
qemu-devel@nongnu.org, Stefan Hajnoczi <stefanha@redhat.com>,
Max Reitz <mreitz@redhat.com>
Subject: Re: [PATCH v4 6/6] block-copy: atomic .cancelled and .finished fields in BlockCopyCallState
Date: Tue, 22 Jun 2021 10:15:42 +0200 [thread overview]
Message-ID: <c06306f6-e154-ec58-44cc-33d48d8ccdff@redhat.com> (raw)
In-Reply-To: <fcb8849c-bedf-aacc-3831-0239d89af2d6@virtuozzo.com>
On 19/06/21 22:06, Vladimir Sementsov-Ogievskiy wrote:
>>
>> - assert(call_state->finished);
>> + assert(qatomic_load_acquire(&call_state->finished));
>
> Hmm. Here qatomic_load_acquire protects nothing (assertion will crash if
> not yet finished anyway). So, caller is double sure that block-copy is
> finished.
It does. If it returns true, you still want the load of finished to
happen before the reads that follow.
Otherwise I agree with your remarks.
Paolo
> Also it's misleading: if we think that it do some protection, we are
> doing wrong thing: assertions may be simply compiled out, we can't rely
> on statements inside assert() to be executed.
>
> So, let's use simple qatomic_read here too.
>
>> if (error_is_read) {
>> *error_is_read = call_state->error_is_read;
>> }
next prev parent reply other threads:[~2021-06-22 8:16 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-14 7:33 [PATCH v4 0/6] block-copy: protect block-copy internal structures Emanuele Giuseppe Esposito
2021-06-14 7:33 ` [PATCH v4 1/6] block-copy: small refactor in block_copy_task_entry and block_copy_common Emanuele Giuseppe Esposito
2021-06-19 14:33 ` Vladimir Sementsov-Ogievskiy
2021-06-14 7:33 ` [PATCH v4 2/6] block-copy: streamline choice of copy_range vs. read/write Emanuele Giuseppe Esposito
2021-06-19 15:05 ` Vladimir Sementsov-Ogievskiy
2021-06-19 18:23 ` Vladimir Sementsov-Ogievskiy
2021-06-14 7:33 ` [PATCH v4 3/6] block-copy: improve comments of BlockCopyTask and BlockCopyState types and functions Emanuele Giuseppe Esposito
2021-06-19 15:23 ` Vladimir Sementsov-Ogievskiy
2021-06-19 18:31 ` Vladimir Sementsov-Ogievskiy
2021-06-21 8:13 ` Emanuele Giuseppe Esposito
2021-06-22 9:20 ` Vladimir Sementsov-Ogievskiy
2021-06-21 7:59 ` Emanuele Giuseppe Esposito
2021-06-22 9:16 ` Vladimir Sementsov-Ogievskiy
2021-06-19 17:27 ` Vladimir Sementsov-Ogievskiy
2021-06-21 8:21 ` Emanuele Giuseppe Esposito
2021-06-19 18:53 ` Vladimir Sementsov-Ogievskiy
2021-06-21 8:28 ` Emanuele Giuseppe Esposito
2021-06-14 7:33 ` [PATCH v4 4/6] block-copy: move progress_set_remaining in block_copy_task_end Emanuele Giuseppe Esposito
2021-06-14 7:33 ` [PATCH v4 5/6] block-copy: add a CoMutex Emanuele Giuseppe Esposito
2021-06-19 19:34 ` Vladimir Sementsov-Ogievskiy
2021-06-14 7:33 ` [PATCH v4 6/6] block-copy: atomic .cancelled and .finished fields in BlockCopyCallState Emanuele Giuseppe Esposito
2021-06-19 20:06 ` Vladimir Sementsov-Ogievskiy
2021-06-21 9:30 ` Emanuele Giuseppe Esposito
2021-06-22 9:56 ` Vladimir Sementsov-Ogievskiy
2021-06-22 8:15 ` Paolo Bonzini [this message]
2021-06-22 9:36 ` Vladimir Sementsov-Ogievskiy
2021-06-22 10:20 ` Paolo Bonzini
2021-06-22 10:39 ` Vladimir Sementsov-Ogievskiy
2021-06-22 20:57 ` Emanuele Giuseppe Esposito
2021-06-23 10:06 ` Paolo Bonzini
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