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[194.230.155.141]) by smtp.gmail.com with ESMTPSA id m14sm15811966edd.63.2021.04.20.05.51.04 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 20 Apr 2021 05:51:05 -0700 (PDT) Subject: Re: [RFC PATCH 1/3] block-copy: improve documentation for BlockCopyTask type and functions To: Vladimir Sementsov-Ogievskiy , qemu-block@nongnu.org References: <20210420100416.30713-1-eesposit@redhat.com> <20210420100416.30713-2-eesposit@redhat.com> <9576b9d5-c40b-14d4-399f-4d14473433bb@virtuozzo.com> From: Emanuele Giuseppe Esposito Message-ID: <2210f74d-53f8-caf3-6f7b-6f2478d8d507@redhat.com> Date: Tue, 20 Apr 2021 14:51:03 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.8.1 MIME-Version: 1.0 In-Reply-To: <9576b9d5-c40b-14d4-399f-4d14473433bb@virtuozzo.com> Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=eesposit@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=170.10.133.124; envelope-from=eesposit@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -27 X-Spam_score: -2.8 X-Spam_bar: -- X-Spam_report: (-2.8 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, NICE_REPLY_A=-0.001, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=unavailable autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Kevin Wolf , Paolo Bonzini , John Snow , qemu-devel@nongnu.org, Max Reitz Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 20/04/2021 14:03, Vladimir Sementsov-Ogievskiy wrote: > 20.04.2021 13:04, Emanuele Giuseppe Esposito wrote: >> As done in BlockCopyCallState, categorize BlockCopyTask >> in IN, State and OUT fields. This is just to understand >> which field has to be protected with a lock. >> >> Also add coroutine_fn attribute to block_copy_task_create, >> because it is only usedn block_copy_dirty_clusters, a coroutine >> function itself. >> >> Signed-off-by: Emanuele Giuseppe Esposito >> --- >>   block/block-copy.c | 15 +++++++++++---- >>   1 file changed, 11 insertions(+), 4 deletions(-) >> >> diff --git a/block/block-copy.c b/block/block-copy.c >> index 39ae481c8b..03df50a354 100644 >> --- a/block/block-copy.c >> +++ b/block/block-copy.c >> @@ -48,25 +48,32 @@ typedef struct BlockCopyCallState { >>       QLIST_ENTRY(BlockCopyCallState) list; >>       /* State */ >> -    int ret; >>       bool finished; >>       QemuCoSleepState *sleep_state; >>       bool cancelled; >>       /* OUT parameters */ >> +    int ret; > > Hmm. Somehow, ret may be considered is part of state too.. But I don't > really care. Here it looks not bad. Will see how and what you are going > protect by new lock. > > Note, that ret is concurently set in block_copy_task_entry.. It is set but as far as I understood it contains the result of the operation (thus OUT), correct? > >>       bool error_is_read; >>   } BlockCopyCallState; >>   typedef struct BlockCopyTask { >> +    /* IN parameters. Initialized in block_copy_task_create() >> +     * and never changed. >> +     */ > > It's wrong about task field, as it has "ret" inside. Not sure I understand what you mean here. > >>       AioTask task; >> - >>       BlockCopyState *s; >>       BlockCopyCallState *call_state; >> + >> +    /* State */ >>       int64_t offset; > > I think, offset is never changed after block_copy_task_create().. right, will revert that for offset > >>       int64_t bytes; >>       bool zeroes; >> -    QLIST_ENTRY(BlockCopyTask) list; >>       CoQueue wait_queue; /* coroutines blocked on this task */ >> + >> +    /* To reference all call states from BlockCopyTask */ > > Amm.. Actually, > > To reference all tasks from BlockCopyState right, agree, thanks > >> +    QLIST_ENTRY(BlockCopyTask) list; >> + >>   } BlockCopyTask; >>   static int64_t task_end(BlockCopyTask *task) >> @@ -153,7 +160,7 @@ static bool coroutine_fn >> block_copy_wait_one(BlockCopyState *s, int64_t offset, >>    * Search for the first dirty area in offset/bytes range and create >> task at >>    * the beginning of it. >>    */ >> -static BlockCopyTask *block_copy_task_create(BlockCopyState *s, >> +static BlockCopyTask *coroutine_fn >> block_copy_task_create(BlockCopyState *s, >>                                                BlockCopyCallState >> *call_state, >>                                                int64_t offset, int64_t >> bytes) >>   { >> > > We mark by "coroutine_fn" functions that can be called _only_ from > coroutine context. In my opinion, block_copy_task_create is a static function and it's called only by another coroutine_fn, block_copy_dirty_clusters, so it matches what you just wrote above. > block_copy_task_create() may be called from any > context, both coroutine and non-coroutine. So, it shouldn't have this mark. Thank you, Emanuele