From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pf1-f177.google.com (mail-pf1-f177.google.com [209.85.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id D2E5C42315E for ; Fri, 22 May 2026 15:02:23 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.210.177 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779462147; cv=none; b=YtVLvdeK7lzcqUJr2GhqgdoGrxCkubHZGgMhNkxkdz54Y7KtC1hF7s/SVsWzslzxB23oPUWceXqwGVL2aTRQ1o20qJYQBpl/cFVbGIrGip/ZSdTBL2G//USpoYqK0150GyJ0rgDuVLGUqavgttXe5k2wEvlwzSRENyWbPAp17gg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779462147; c=relaxed/simple; bh=OAwoS6WYo6gq8SOThj7G/LsS3ousVQdJn0oVyZYrOQk=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=koYu9L232s8O1eacDarRmeYTzrnXyerNC2NXRrNb4jSETS0epBTa4tTc0PmBk9je0FTyzeKPkAyWcuQpPPGMEpQBPRmGz5qQ7lSVX9N5ZofU6fJ9HxNmHyoyoj8LYtuCU3c1uKtVAldr6w6l+uOT/DSMG1GtMTZ25tvcxntuvBo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=qp8yE/UE; arc=none smtp.client-ip=209.85.210.177 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="qp8yE/UE" Received: by mail-pf1-f177.google.com with SMTP id d2e1a72fcca58-8367df48711so3237051b3a.1 for ; Fri, 22 May 2026 08:02:21 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1779462140; x=1780066940; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=NV1iGgeUXsI6eaSi8LS7eYC/k6KaxInCak9T2RCHqa4=; b=qp8yE/UEmIzzp9Z7IRtHQ3U5IWLTD4WL3jo7jQSg9xxV26cf2lUAnfSBGdu7MI3nEu VsKicHxipRQ3pvPcpn8cbAcF3cubXwNBEjqWobFYfZ9slJWlsIHHo2qm1To8fmQ3ZFxl TGe6PBvDf4UTQyeaMhWLkndGCVzPlwK916YzuPIpekS+spTIgHh6o0C7/HLJvpYrpkEm ykqDJnoQK3scMCS8hkGvrlwG5a44oTqpae9rIAAio3qGx3AVgVZQ75knDUIjYbIKAs3M kdPSAWdyNA+59KZrKxrXl4SCXb3podJiOlPZBcbXsK0oDBwXH5tman8EIRybqbuP7hsB HOVQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1779462140; x=1780066940; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-gg:x-gm-message-state:from :to:cc:subject:date:message-id:reply-to; bh=NV1iGgeUXsI6eaSi8LS7eYC/k6KaxInCak9T2RCHqa4=; b=aKObK49K6nhvbxhI+vZ9XYqdDvjdGneHrtUi6k/is0tKmCB23LK+9FKGOlpIMeKhre flS0Nm6CGuIIqYCAxE87Hz8rOukXYNLkc/3qN3SW2gOc4J3Du/sRWmlglZiclcA0aRqp KyHPALn8VJHvNjq9NJYJ1HCNuAEpKkfgDM5NYtQicJA2vVYaAVdoRE+3BkThYK6c2qA1 tsGBSR0FNN0zvjlOImO7AiCz+f81uX1G9z7NMevicOCcC9AxtBVxO2zuBz2QRivBmva6 8Qe01JdURZDXQdFtW5rbC+c1WHm6S+m6/BMROWb/UhXJfqhrxZBjfS6GjE8Hc3qTUuqb k0HA== X-Forwarded-Encrypted: i=1; AFNElJ9WgodKzBMaRlRbsNALnslfiB6Xc2M9Lmx+TfGmMGSO8O9gUSP3kbmxGgGNGXb2ybrsAXLNz8QJCHU=@vger.kernel.org X-Gm-Message-State: AOJu0YzzyehJHk+KxGC8+T3+0VKp6CFhDz1M3heEBOly8YerxRW5bpTh 7V9FsGtcQLMFmL/VQKqVIsWiU3ADApFcYK2Czz5vR6HuZb605zdNDCZe X-Gm-Gg: Acq92OEJCtZAcd+7JriTrpDe/fSg4Cb7lvZdmjwvC8bPfYJH+Bd+kEfE/4mKEOU1X1E whF/uurb6zqR/Aqyt3aWOSG3wXYgT7xmqIqYpoWN1xRJzOIN2Z1wXkJCSyCbH5IuPjgKZKAFVJ7 AsY74mZJCY7iHFxRuaRxGruAX111LNq7JqpIbvvZqtw8EGlg2bxDIMtdP7pt1/vyOYNQ66lIpoN p0o4BHClqpaAynmpJsiVTMd5CJ86Yi11NvNXKOWe+xrw1j0jCUlFRhJDXOKexKdZMQAFeqm0nv0 FbXz83qSRP+AU7FdlehP+BoXwbUKCM82TY/A/rkJ26GCsnlhKvUhW6uz8dFUfgheYLS2oa6j1Gq OSxjDqOoPy9nEtrGwcUDMchexvR0urJYalITTYj4/acCZkn5BQswoqcMzLLpghCqV522beQgIw1 12V/GBOQ== X-Received: by 2002:a05:6a00:e11:b0:7e8:4471:ae55 with SMTP id d2e1a72fcca58-8415f439579mr4279178b3a.33.1779462139137; Fri, 22 May 2026 08:02:19 -0700 (PDT) Received: from csl-conti-dell7858.ntu.edu.sg ([155.69.195.57]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-84164ac9522sm2216488b3a.11.2026.05.22.08.02.17 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 22 May 2026 08:02:18 -0700 (PDT) From: Maoyi Xie To: Vinod Koul Cc: Frank Li , Geert Uytterhoeven , dmaengine@vger.kernel.org, linux-renesas-soc@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v2] dmaengine: mpc512x: fix dead empty check in mpc_dma_prep_slave_sg() Date: Fri, 22 May 2026 23:02:14 +0800 Message-Id: <20260522150214.95651-1-maoyixie.tju@gmail.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20260521144755.3476353-2-maoyixie.tju@gmail.com> References: <20260521144755.3476353-2-maoyixie.tju@gmail.com> Precedence: bulk X-Mailing-List: dmaengine@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit mpc_dma_prep_slave_sg() reads mchan->free with list_first_entry() and then tests the returned pointer against NULL. list_first_entry() never returns NULL. On an empty free list it returns container_of(&mchan->free, struct mpc_dma_desc, node), an aliased pointer derived from the list head. The recovery path (drop lock, scan completed list, return NULL) is dead code. Use list_first_entry_or_null() so the empty case returns NULL and the existing recovery path runs as intended. The same shape has been cleaned up elsewhere, for example in commit fbb8bc408027 ("net: qed: Remove redundant NULL checks after list_first_entry()"), commit c708d3fad421 ("crypto: atmel - use list_first_entry_or_null to simplify find_dev"), and commit 10379171f346 ("ksmbd: use list_first_entry_or_null for opinfo_get_list()"). This site was missed by those cleanups. Reviewed-by: Frank Li Signed-off-by: Maoyi Xie --- v2: Trim two paragraphs from the commit message per Frank Li's nit on v1. No code change. Carry forward Frank's Reviewed-by. Drop the rz-dmac patch from v1: Geert pointed out that Claudiu's "[PATCH v5 09/17] dmaengine: sh: rz-dmac: Use virt-dma APIs for channel descriptor processing" rewrites rz_dmac_chan_get_residue() through vchan_find_desc() and removes ld_active, which supersedes the fix. https://lore.kernel.org/r/20260512121219.216159-10-claudiu.beznea.uj@bp.renesas.com v1: https://lore.kernel.org/r/20260521144755.3476353-2-maoyixie.tju@gmail.com drivers/dma/mpc512x_dma.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/dma/mpc512x_dma.c b/drivers/dma/mpc512x_dma.c index 0adc8e01057e..f5934136efc4 100644 --- a/drivers/dma/mpc512x_dma.c +++ b/drivers/dma/mpc512x_dma.c @@ -706,8 +706,8 @@ mpc_dma_prep_slave_sg(struct dma_chan *chan, struct scatterlist *sgl, for_each_sg(sgl, sg, sg_len, i) { spin_lock_irqsave(&mchan->lock, iflags); - mdesc = list_first_entry(&mchan->free, - struct mpc_dma_desc, node); + mdesc = list_first_entry_or_null(&mchan->free, + struct mpc_dma_desc, node); if (!mdesc) { spin_unlock_irqrestore(&mchan->lock, iflags); /* Try to free completed descriptors */ -- 2.34.1