From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pg1-f180.google.com (mail-pg1-f180.google.com [209.85.215.180]) (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 29F873B5E01 for ; Tue, 9 Jun 2026 22:19:50 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.215.180 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781043592; cv=none; b=po/nGgYxFsPgcG3b8dtOl7iKNE4XpYABc0i8DjV45OU5uvfFFMnknZ9gHhKSHzUHy/mz7HziT3nqsd4qmA/nLUMwIbx+bFiiVEPehzQjOegw/ngo3WzpOb4gb3M8ru66y1e5oI6KCVDL7u7c3j8LOtBGrcWkyT9yPMj/eMprZQQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781043592; c=relaxed/simple; bh=RWGgQ+fIx5zEE7hIr/SdyaUnQQt8wM2jyEcHAPXGR1o=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=naHViGyXKnk1IqU1iSpsHQSj0fkrXD1OrRzuHnPAYlvhV4px9AY5dQrN64IxsFkPLkpFqIPrU5N0pAavAzd2HMUJXQdKFezvgeIq5lZ+QA0B1By3aTQvU2ztkyInVRaWVTuuXHECvkeh7NaghtbSvBTo9D5SEELVZJggOwsXgrQ= 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=cwinqtx3; arc=none smtp.client-ip=209.85.215.180 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="cwinqtx3" Received: by mail-pg1-f180.google.com with SMTP id 41be03b00d2f7-c85d8615b09so3551274a12.3 for ; Tue, 09 Jun 2026 15:19:50 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1781043590; x=1781648390; darn=lists.linux.dev; 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=twBxGuT7Vyeqc2tSt+1Cu5dVnnD709Tu79Udll0+igY=; b=cwinqtx3d540ZjdHvDe/uMX+HeH5xzHntQ2AvkQm2dFbbuRQdHwHuM67JFGZzrab/8 gG7M6GUOgqXraO+9HnGgzLEMViRic6EVnA64TJO0HRpuVQR7KzKsWH+jE6rqVNaO3qCY z6NEVzoHpdc8hZ5z4lImDMI2jw0kpqobEjeLpA9x5SeQsNPwvFnviDZdBb9zwZbuZHC5 4fHHNN/12CWVB40DU/CetUykYK87rIEiWPoMKf0IVgaDD1Yq4LJx/8kByNCmYY/LjUo1 haPDsur8tCpWtZ2l6NtIE7zKmV8bB7eUOoBjLyMZ+bsu34jZoFJeHNT1kvTZBDwB42LC mX9A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1781043590; x=1781648390; 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=twBxGuT7Vyeqc2tSt+1Cu5dVnnD709Tu79Udll0+igY=; b=BHZm7Z1BDLnMn/0R3hXN43EmHnO0VRPi6zvI8RYiUh3PbAX1jYUerXnuLRk65rLc70 KDEOVjvrgQ7M1wo3BIcu5AtXO8VtNd/qJRcxs9eBBSWA+oRUhdljTOg+182137hbsUW8 8CWd4xNgfimI8CLAFU6CBU7PtRS2mvfZY3sV4ndAJz8210GqF1PKZK1wBQH/I9X9D7nQ 0UsvS7d7IWEApbZV5nO5ToHM7sFx9Auu38bIaQB5u1r9IVc/QtYXaqzDkfLfQzffSSRl jropLYfPQbEy3HKc+l2B1ECAKTc5PMmm1kD1gCVetU7+uLoP6A/wM5zvIe3PYGad1HWf YJQg== X-Forwarded-Encrypted: i=1; AFNElJ8VuPfaT6sulT/HTYGH6/UfC6cSh+HZvbwYasowxwCwda8MbGVVR+Z/7RNq1HIGSwkGRQCY@lists.linux.dev X-Gm-Message-State: AOJu0Yyffjf0EbP/aCBGSw3n9Wej3NAxPGwimKmU35O5ef8h7J6BwMNC 9G/fNUh7hqUkzwFrSFsBM0isOrvymv0V4D7Evb/Yqt30YVIrGSrokgzn X-Gm-Gg: Acq92OHIm8wbd44+vyRLt5aw6RH+FJB+2e8JBsKpPW3xVskPLo1ziJzOMqSOOr550qJ tySoqvrOlIbhDPzd+Z0+k7Q4A45SxjrCHMYU6F/91oI24tcgFv0rrp/4l1N0pZb+iIxnYZBz2XO d9DKAFU1RS5kb8C9dZ9B2C7Yq4gatvkQXTLV3f+5YzEnpqNhj9Flq8NER8O95s8oc/q9Ygyxh4x i74N/Vcjw5lmwx5bpqiU7OOIeVzaQuOEa1fF4QsO2tPOKgnDgbxQlf8suGz9uXkUnh4nD6XFOH+ 6I4F0iW0S3rlejcFYlWZ8eh5ypoIQiyoRZQqXmku5qd5OAQ9xRz8/2z16gJuaH7QiU57KnwUwAy 5aFzkGfqeG1qBRxxtHEVzjMWuHnhiWL3e8snyOcrlic5yQQP8o0GoY5kGMyFiIflfexOgZDuWCw eRHwwEN9LjMVzDEMY7qAa3wKsfYWFjMyNIaRPuJBM3MUzA5b3whX5+qq56kXonqtV+hnTIAkBQk UgzhxOcJYqEUZPjZNpUP3WxbGs4LhWEOntPAXeuqfMFXg== X-Received: by 2002:a05:6a20:1609:b0:39f:3ca8:a33b with SMTP id adf61e73a8af0-3b4ccd764e8mr27610402637.17.1781043590415; Tue, 09 Jun 2026 15:19:50 -0700 (PDT) Received: from ryzen ([2601:644:8000:5b5d:7285:c2ff:fe45:8a32]) by smtp.gmail.com with ESMTPSA id 41be03b00d2f7-c85df04ff24sm19661834a12.14.2026.06.09.15.19.47 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 09 Jun 2026 15:19:49 -0700 (PDT) From: Rosen Penev To: dmaengine@vger.kernel.org Cc: Vinod Koul , Frank Li , Zhang Wei , Nathan Chancellor , Nick Desaulniers , Bill Wendling , Justin Stitt , linux-kernel@vger.kernel.org (open list), linuxppc-dev@lists.ozlabs.org (open list:FREESCALE DMA DRIVER), llvm@lists.linux.dev (open list:CLANG/LLVM BUILD SUPPORT:Keyword:\b(?i:clang|llvm)\b) Subject: [PATCHv3 02/15] dmaengine: fsldma: drop desc_lock before invoking client callback Date: Tue, 9 Jun 2026 15:19:13 -0700 Message-ID: <20260609221926.35538-3-rosenp@gmail.com> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260609221926.35538-1-rosenp@gmail.com> References: <20260609221926.35538-1-rosenp@gmail.com> Precedence: bulk X-Mailing-List: llvm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit fsldma_run_tx_complete_actions() calls dmaengine_desc_get_callback_invoke() while still holding chan->desc_lock. If the client submits a new transaction from their completion callback, fsl_dma_tx_submit() tries to acquire the same non-recursive spinlock, causing a self-deadlock. Fix by extracting the callback info under the lock, removing the descriptor from ld_running, dropping the lock, then invoking the callback and running dependencies outside the lock. Assisted-by: opencode:big-pickle Signed-off-by: Rosen Penev --- drivers/dma/fsldma.c | 108 ++++++++++++++++++++++--------------------- 1 file changed, 55 insertions(+), 53 deletions(-) diff --git a/drivers/dma/fsldma.c b/drivers/dma/fsldma.c index 0e2f84862261..455d21d738de 100644 --- a/drivers/dma/fsldma.c +++ b/drivers/dma/fsldma.c @@ -496,16 +496,19 @@ static void fsldma_clean_completed_descriptor(struct fsldma_chan *chan) } /** - * fsldma_run_tx_complete_actions - cleanup a single link descriptor + * fsldma_run_tx_complete_actions - unmap and extract callback from a descriptor * @chan: Freescale DMA channel - * @desc: descriptor to cleanup and free + * @desc: descriptor to process * @cookie: Freescale DMA transaction identifier + * @cb: returned callback information * - * This function is used on a descriptor which has been executed by the DMA - * controller. It will run any callbacks, submit any dependencies. + * Unmap the descriptor if it has been submitted and extract its callback + * into @cb. The caller must invoke the callback and run dependencies + * after releasing chan->desc_lock. */ static dma_cookie_t fsldma_run_tx_complete_actions(struct fsldma_chan *chan, - struct fsl_desc_sw *desc, dma_cookie_t cookie) + struct fsl_desc_sw *desc, dma_cookie_t cookie, + struct dmaengine_desc_callback *cb) { struct dma_async_tx_descriptor *txd = &desc->async_tx; dma_cookie_t ret = cookie; @@ -514,49 +517,14 @@ static dma_cookie_t fsldma_run_tx_complete_actions(struct fsldma_chan *chan, if (txd->cookie > 0) { ret = txd->cookie; - dma_descriptor_unmap(txd); - /* Run the link descriptor callback function */ - dmaengine_desc_get_callback_invoke(txd, NULL); } - /* Run any dependencies */ - dma_run_dependencies(txd); + dmaengine_desc_get_callback(txd, cb); return ret; } -/** - * fsldma_clean_running_descriptor - move the completed descriptor from - * ld_running to ld_completed - * @chan: Freescale DMA channel - * @desc: the descriptor which is completed - * - * Free the descriptor directly if acked by async_tx api, or move it to - * queue ld_completed. - */ -static void fsldma_clean_running_descriptor(struct fsldma_chan *chan, - struct fsl_desc_sw *desc) -{ - /* Remove from the list of transactions */ - list_del(&desc->node); - - /* - * the client is allowed to attach dependent operations - * until 'ack' is set - */ - if (!async_tx_test_ack(&desc->async_tx)) { - /* - * Move this descriptor to the list of descriptors which is - * completed, but still awaiting the 'ack' bit to be set. - */ - list_add_tail(&desc->node, &chan->ld_completed); - return; - } - - dma_pool_free(chan->desc_pool, desc, desc->async_tx.phys); -} - /** * fsl_chan_xfer_ld_queue - transfer any pending transactions * @chan : Freescale DMA channel @@ -635,22 +603,23 @@ static void fsl_chan_xfer_ld_queue(struct fsldma_chan *chan) */ static void fsldma_cleanup_descriptors(struct fsldma_chan *chan) { - struct fsl_desc_sw *desc, *_desc; + struct fsl_desc_sw *desc; dma_cookie_t cookie = 0; dma_addr_t curr_phys = get_cdar(chan); int seen_current = 0; fsldma_clean_completed_descriptor(chan); - /* Run the callback for each descriptor, in order */ - list_for_each_entry_safe(desc, _desc, &chan->ld_running, node) { - /* - * do not advance past the current descriptor loaded into the - * hardware channel, subsequent descriptors are either in - * process or have not been submitted - */ - if (seen_current) - break; + /* + * Take descriptors one at a time from the front of the running + * queue. We re-read the list each iteration so that we don't + * chase a stale next pointer across the lock-drop below. + */ + while (!seen_current && !list_empty(&chan->ld_running)) { + struct dmaengine_desc_callback cb; + + desc = list_first_entry(&chan->ld_running, + struct fsl_desc_sw, node); /* * stop the search if we reach the current descriptor and the @@ -662,9 +631,42 @@ static void fsldma_cleanup_descriptors(struct fsldma_chan *chan) break; } - cookie = fsldma_run_tx_complete_actions(chan, desc, cookie); + cookie = fsldma_run_tx_complete_actions(chan, desc, cookie, &cb); - fsldma_clean_running_descriptor(chan, desc); + /* + * Remove from the running list before dropping the lock so + * that terminate_all cannot free this descriptor while we + * call into the client below. + */ + list_del(&desc->node); + + /* + * Prevent dma_run_dependencies() from calling + * fsl_chan_xfer_ld_queue() while we are not holding the + * lock. That would splice pending descriptors into + * ld_running before they have been completed by hardware. + * fsl_chan_xfer_ld_queue at the end of this function will + * re-evaluate the situation. + */ + chan->idle = false; + + /* + * Drop the lock before invoking the client callback, since + * the DMAengine API explicitly allows clients to submit new + * transactions from their completion callback. Otherwise + * we self-deadlock on chan->desc_lock. + */ + spin_unlock(&chan->desc_lock); + dmaengine_desc_callback_invoke(&cb, NULL); + dma_run_dependencies(&desc->async_tx); + spin_lock(&chan->desc_lock); + + chan->idle = true; + + if (!async_tx_test_ack(&desc->async_tx)) + list_add_tail(&desc->node, &chan->ld_completed); + else + dma_pool_free(chan->desc_pool, desc, desc->async_tx.phys); } /* -- 2.54.0