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[79.124.17.100]) by mx.google.com with ESMTP id 4fb4d7f45d1cf-5c88249cba5si2954347a12.436.2024.09.28.02.26.11; Sat, 28 Sep 2024 02:26:11 -0700 (PDT) Received-SPF: pass (google.com: domain of ffmpeg-devel-bounces@ffmpeg.org designates 79.124.17.100 as permitted sender) client-ip=79.124.17.100; Authentication-Results: mx.google.com; dkim=neutral (body hash did not verify) header.i=@gmail.com header.s=20230601 header.b=jBA9Jfov; spf=pass (google.com: domain of ffmpeg-devel-bounces@ffmpeg.org designates 79.124.17.100 as permitted sender) smtp.mailfrom=ffmpeg-devel-bounces@ffmpeg.org; dmarc=fail (p=NONE sp=QUARANTINE dis=NONE) header.from=gmail.com; dara=fail header.i=@gmail.com Received: from [127.0.1.1] (localhost [127.0.0.1]) by ffbox0-bg.mplayerhq.hu (Postfix) with ESMTP id D5DA068DB5E; Tue, 24 Sep 2024 17:17:10 +0300 (EEST) X-Original-To: ffmpeg-devel@ffmpeg.org Delivered-To: ffmpeg-devel@ffmpeg.org Received: from mail-pl1-f172.google.com (mail-pl1-f172.google.com [209.85.214.172]) by ffbox0-bg.mplayerhq.hu (Postfix) with ESMTPS id 5AF4768A604 for ; Tue, 24 Sep 2024 17:17:04 +0300 (EEST) Received: by mail-pl1-f172.google.com with SMTP id d9443c01a7336-2054e22ce3fso56141855ad.2 for ; Tue, 24 Sep 2024 07:17:04 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1727187422; x=1727792222; darn=ffmpeg.org; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to; bh=49rdA3AAMUZ1QmRSoOWQzLK2EVmuqA00sgjUoYUWgmU=; b=jBA9JfovPLIr39kBcunjIONP3R18BjqUN6sb5mA6HdIPq5vdk6veTkwlz/auRDxpm/ Ff8gaHwFOtCygRbWfaOnlgROLzcIqNjFvX5/HpJWvPxzkLj4KZBElmE8KcUrf9heMeoU Kf/3wMLWE/AHymhjSZ9kopRjXTllA2B3y2MsgfDmw3Rp7I3mH7p1IzjZZ48MST2VIbH7 XoeKolXaQBgoQrZaQiDpv3V65v//sqJqTGDvZoPJYMStZFxOX0vDsA/pyxhDSGatX+9n Aan7ll+I3aXWO9pYtONH9AqAq48I+QfUDIdKjJRUHB9JEAl4pXf7rkc+HYZ9ElgJecVK WPGQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1727187422; x=1727792222; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=49rdA3AAMUZ1QmRSoOWQzLK2EVmuqA00sgjUoYUWgmU=; b=OIEBApKKglEgC9d+aPbVEtG2a0Df8ZWz4EjNwC7NW8GtQ8BfGwdgI6C9YZQ3pMipV5 lv/BQnveWifGnSRYNijeOrddgevkSFkwnM22GA0e6/IhNkJLkRw2g1z3QSBhIt7qQG+O RaDlSvpDRmJHzIrydnSV8qLq/sOdQxfz+U83/7alZ9O/wrZ/UZC4VdO1V5A6W/iB6Lvf PuMfLMv26p1Eg7l3CHzfN76uMDeSMXGtXmzkOWxDZjwyJoM+5NcmzLcvSTLH7MpirgSF KzhO03WROXnOSwZun5xgngYSNhOmtCuIkmFxQcEBpz9v0u8H1jegEIiJaRwXaph4dyn2 03Sw== X-Gm-Message-State: AOJu0YyktJE5pnb5ypkp7j/nLPkj2qPpghXml2iDmbJ0MUSJZMs+nSpE hoHoPU2zrBtf2POj0q0QnZhKVvm/LmQ1If5kR5Bsa1xvPQATo0xy+2bqKffsZ18= X-Received: by 2002:a17:902:ccd1:b0:208:d893:5707 with SMTP id d9443c01a7336-208d8935c47mr197945335ad.1.1727187422144; Tue, 24 Sep 2024 07:17:02 -0700 (PDT) Received: from localhost ([112.64.8.17]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-20af16e5478sm10911715ad.1.2024.09.24.07.17.00 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 24 Sep 2024 07:17:01 -0700 (PDT) From: Nuo Mi To: ffmpeg-devel@ffmpeg.org Date: Tue, 24 Sep 2024 22:16:57 +0800 Message-Id: <20240924141658.39574-1-nuomi2021@gmail.com> X-Mailer: git-send-email 2.34.1 MIME-Version: 1.0 Subject: [FFmpeg-devel] [PATCH 1/2] avutils/executor: remove unused ready callback X-BeenThere: ffmpeg-devel@ffmpeg.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: FFmpeg development discussions and patches List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: FFmpeg development discussions and patches Cc: Nuo Mi Errors-To: ffmpeg-devel-bounces@ffmpeg.org Sender: "ffmpeg-devel" X-TUID: wPBijGBBJQ65 Due to the nature of multithreading, using a "ready check" mechanism may introduce a deadlock. For example: Suppose all tasks have been submitted to the executor, and the last thread checks the entire list and finds no ready tasks. It then goes to sleep, waiting for a new task. However, for some multithreading-related reason, a task becomes ready after the check. Since no other thread is aware of this and no new tasks are being added to the executor, a deadlock occurs. In VVC, this function is unnecessary because we use a scoreboard. All tasks submitted to the executor are ready tasks. --- libavcodec/vvc/thread.c | 8 -------- libavutil/executor.c | 6 ++---- libavutil/executor.h | 3 --- 3 files changed, 2 insertions(+), 15 deletions(-) diff --git a/libavcodec/vvc/thread.c b/libavcodec/vvc/thread.c index 86a7753c6a..6208cc1811 100644 --- a/libavcodec/vvc/thread.c +++ b/libavcodec/vvc/thread.c @@ -372,13 +372,6 @@ static int task_is_stage_ready(VVCTask *t, int add) return task_has_target_score(t, stage, score); } -static int task_ready(const AVTask *_t, void *user_data) -{ - VVCTask *t = (VVCTask*)_t; - - return task_is_stage_ready(t, 0); -} - #define CHECK(a, b) \ do { \ if ((a) != (b)) \ @@ -689,7 +682,6 @@ AVExecutor* ff_vvc_executor_alloc(VVCContext *s, const int thread_count) s, sizeof(VVCLocalContext), task_priority_higher, - task_ready, task_run, }; return av_executor_alloc(&callbacks, thread_count); diff --git a/libavutil/executor.c b/libavutil/executor.c index bfce2ac444..64e6cc0775 100644 --- a/libavutil/executor.c +++ b/libavutil/executor.c @@ -79,10 +79,8 @@ static void add_task(AVTask **prev, AVTask *t) static int run_one_task(AVExecutor *e, void *lc) { AVTaskCallbacks *cb = &e->cb; - AVTask **prev; + AVTask **prev = &e->tasks; - for (prev = &e->tasks; *prev && !cb->ready(*prev, cb->user_data); prev = &(*prev)->next) - /* nothing */; if (*prev) { AVTask *t = remove_task(prev, *prev); if (e->thread_count > 0) @@ -143,7 +141,7 @@ AVExecutor* av_executor_alloc(const AVTaskCallbacks *cb, int thread_count) { AVExecutor *e; int has_lock = 0, has_cond = 0; - if (!cb || !cb->user_data || !cb->ready || !cb->run || !cb->priority_higher) + if (!cb || !cb->user_data || !cb->run || !cb->priority_higher) return NULL; e = av_mallocz(sizeof(*e)); diff --git a/libavutil/executor.h b/libavutil/executor.h index 0eb21c10c8..7af53c92ce 100644 --- a/libavutil/executor.h +++ b/libavutil/executor.h @@ -36,9 +36,6 @@ typedef struct AVTaskCallbacks { // return 1 if a's priority > b's priority int (*priority_higher)(const AVTask *a, const AVTask *b); - // task is ready for run - int (*ready)(const AVTask *t, void *user_data); - // run the task int (*run)(AVTask *t, void *local_context, void *user_data); } AVTaskCallbacks;