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[130.37.198.127]) by smtp.gmail.com with ESMTPSA id kv5-20020a17090778c500b0087c4f420af2sm2237576ejc.4.2023.01.28.08.26.24 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 28 Jan 2023 08:26:24 -0800 (PST) From: Pietro Borrello Date: Sat, 28 Jan 2023 16:26:15 +0000 Subject: [PATCH] sched: pick_next_rt_entity(): checked list_entry MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20230128-list-entry-null-check-sched-v1-1-c93085ee0055@diag.uniroma1.it> X-B4-Tracking: v=1; b=H4sIAKdM1WMC/x2NQQrCMBBFr1Jm7UCblFK8irhIk4kZjFFmoiild 2/q6vP48N4KSsKkcO5WEPqw8rM0GE4d+OTKjZBDYzC9sf1gZsysFalU+WF554w+kb+jtgnobLQh himM0wzNsDglXMQVnw7Hw2klOY6XUOTvP3u5btsOEnGrSoYAAAA= To: Ingo Molnar , Peter Zijlstra , Juri Lelli , Vincent Guittot , Dietmar Eggemann , Steven Rostedt , Ben Segall , Mel Gorman , Daniel Bristot de Oliveira , Valentin Schneider , Dmitry Adamushko Cc: Cristiano Giuffrida , "Bos, H.J." , Jakob Koschel , Ingo Molnar , linux-kernel@vger.kernel.org, Pietro Borrello X-Mailer: b4 0.11.1 X-Developer-Signature: v=1; a=ed25519-sha256; t=1674923184; l=1366; i=borrello@diag.uniroma1.it; s=20221223; h=from:subject:message-id; bh=+TnFwqvslLCYg0C2K2P8kCuVHl8uIbNuMT200eU8tSw=; b=HpcO9b5Bwx8aIXJEbqqDtZ4aVEIDHzsx2KJ5xvruNYaMGJ/OojZjXrBT1YxEjIZqUC/P67bVDvFe +LQ1JpBtAXgkXtYHn7VXe1iToZc0IjGR0jPYgaUyp9xMKI+TtZAN X-Developer-Key: i=borrello@diag.uniroma1.it; a=ed25519; pk=4xRQbiJKehl7dFvrG33o2HpveMrwQiUPKtIlObzKmdY= Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit 326587b84078 ("sched: fix goto retry in pick_next_task_rt()") removed any path which could make pick_next_rt_entity() return NULL. However, BUG_ON(!rt_se) in _pick_next_task_rt() (the only caller of pick_next_rt_entity()) still checks the error condition, which can never happen, since list_entry() never returns NULL. Return list_first_entry_or_null(queue, ...) to allow BUG to check the only possible error condition here: the queue being empty which should never happen. Fixes: 326587b84078 ("sched: fix goto retry in pick_next_task_rt()") Signed-off-by: Pietro Borrello --- kernel/sched/rt.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c index ed2a47e4ddae..6088d5d83b75 100644 --- a/kernel/sched/rt.c +++ b/kernel/sched/rt.c @@ -1777,7 +1777,7 @@ static struct sched_rt_entity *pick_next_rt_entity(struct rt_rq *rt_rq) BUG_ON(idx >= MAX_RT_PRIO); queue = array->queue + idx; - next = list_entry(queue->next, struct sched_rt_entity, run_list); + next = list_first_entry_or_null(queue, struct sched_rt_entity, run_list); return next; } --- base-commit: 2241ab53cbb5cdb08a6b2d4688feb13971058f65 change-id: 20230128-list-entry-null-check-sched-a3f3dfd6d468 Best regards, -- Pietro Borrello