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dkim=none (message not signed) header.d=none;nongnu.org; dmarc=none action=none header.from=virtuozzo.com; Received: from AM7PR08MB5494.eurprd08.prod.outlook.com (2603:10a6:20b:dc::15) by AS8PR08MB6119.eurprd08.prod.outlook.com (2603:10a6:20b:290::10) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.4195.22; Wed, 9 Jun 2021 09:12:06 +0000 Received: from AM7PR08MB5494.eurprd08.prod.outlook.com ([fe80::f928:f4f2:77c0:74b4]) by AM7PR08MB5494.eurprd08.prod.outlook.com ([fe80::f928:f4f2:77c0:74b4%9]) with mapi id 15.20.4195.030; Wed, 9 Jun 2021 09:12:06 +0000 Subject: Re: [PATCH v3 2/5] block-copy: improve comments of BlockCopyTask and BlockCopyState types and functions To: Emanuele Giuseppe Esposito , qemu-block@nongnu.org Cc: John Snow , Kevin Wolf , Max Reitz , Paolo Bonzini , Stefan Hajnoczi , qemu-devel@nongnu.org References: <20210608073344.53637-1-eesposit@redhat.com> <20210608073344.53637-3-eesposit@redhat.com> From: Vladimir Sementsov-Ogievskiy Message-ID: Date: Wed, 9 Jun 2021 12:12:04 +0300 User-Agent: Mozilla/5.0 (X11; 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envelope-from=vsementsov@virtuozzo.com; helo=EUR01-HE1-obe.outbound.protection.outlook.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, MSGID_FROM_MTA_HEADER=0.001, NICE_REPLY_A=-0.001, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H2=-0.001, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 autolearn=ham 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: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" 08.06.2021 10:33, Emanuele Giuseppe Esposito wrote: > As done in BlockCopyCallState, categorize BlockCopyTask > and BlockCopyState in IN, State and OUT fields. > This is just to understand which field has to be protected with a lock. > > .sleep_state is handled in the series "coroutine: new sleep/wake API" > and thus here left as TODO. > > Signed-off-by: Emanuele Giuseppe Esposito > --- > block/block-copy.c | 47 ++++++++++++++++++++++++++++++---------------- > 1 file changed, 31 insertions(+), 16 deletions(-) > > diff --git a/block/block-copy.c b/block/block-copy.c > index d58051288b..b3533a3003 100644 > --- a/block/block-copy.c > +++ b/block/block-copy.c > @@ -56,25 +56,33 @@ typedef struct BlockCopyCallState { > QLIST_ENTRY(BlockCopyCallState) list; > > /* State */ Why previous @list field is not in the state? For sure it's not an IN parameter and should be protected somehow. > - int ret; > bool finished; > - QemuCoSleep sleep; > - bool cancelled; > + QemuCoSleep sleep; /* TODO: protect API with a lock */ > > /* OUT parameters */ > + bool cancelled; > bool error_is_read; > + int ret; > } BlockCopyCallState; > > typedef struct BlockCopyTask { > AioTask task; > > + /* > + * IN parameters. Initialized in block_copy_task_create() > + * and never changed. > + */ > BlockCopyState *s; > BlockCopyCallState *call_state; > int64_t offset; > - int64_t bytes; > - BlockCopyMethod method; > - QLIST_ENTRY(BlockCopyTask) list; > + int64_t bytes; /* only re-set in task_shrink, before running the task */ > + BlockCopyMethod method; /* initialized in block_copy_dirty_clusters() */ hmm. to be precise method is initialized in block_copy_task_create. And after block_copy_task_create finished, task is in the list and can be read by parallel block_copy_dirty_clusters(). So, @bytes is part of State, we must protect it.. method is only read by block_copy_task_entry(), so can be modified without any protection before running the task. > + > + /* State */ > CoQueue wait_queue; /* coroutines blocked on this task */ > + > + /* To reference all call states from BlockCopyState */ That's a misleading comment.. not all sates but all tasks. I don't think we need this new comment, just keep @list in State section. > + QLIST_ENTRY(BlockCopyTask) list; > } BlockCopyTask; > > static int64_t task_end(BlockCopyTask *task) > @@ -90,15 +98,25 @@ typedef struct BlockCopyState { > */ > BdrvChild *source; > BdrvChild *target; > - BdrvDirtyBitmap *copy_bitmap; > + > + /* State */ > int64_t in_flight_bytes; > - int64_t cluster_size; > BlockCopyMethod method; > - int64_t max_transfer; > - uint64_t len; > QLIST_HEAD(, BlockCopyTask) tasks; /* All tasks from all block-copy calls */ > QLIST_HEAD(, BlockCopyCallState) calls; > + /* State fields that use a thread-safe API */ > + BdrvDirtyBitmap *copy_bitmap; > + ProgressMeter *progress; > + SharedResource *mem; > + RateLimit rate_limit; > > + /* > + * IN parameters. Initialized in block_copy_state_new() > + * and never changed. > + */ > + int64_t cluster_size; > + int64_t max_transfer; > + uint64_t len; > BdrvRequestFlags write_flags; > > /* > @@ -114,14 +132,11 @@ typedef struct BlockCopyState { > * In this case, block_copy() will query the source’s allocation status, > * skip unallocated regions, clear them in the copy_bitmap, and invoke > * block_copy_reset_unallocated() every time it does. > + * > + * This field is set in backup_run() before coroutines are run, > + * therefore is an IN. > */ > bool skip_unallocated; > - > - ProgressMeter *progress; > - > - SharedResource *mem; > - > - RateLimit rate_limit; > } BlockCopyState; > > static BlockCopyTask *find_conflicting_task(BlockCopyState *s, > -- Best regards, Vladimir