From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 0E8D5CD98C6 for ; Thu, 11 Jun 2026 03:53:24 +0000 (UTC) Received: from boromir.ozlabs.org (localhost [127.0.0.1]) by lists.ozlabs.org (Postfix) with ESMTP id 4gbTJQ2gGKz2yv2; Thu, 11 Jun 2026 13:53:10 +1000 (AEST) Authentication-Results: lists.ozlabs.org; arc=none smtp.remote-ip="2607:f8b0:4864:20::1036" ARC-Seal: i=1; a=rsa-sha256; d=lists.ozlabs.org; s=201707; t=1781149990; cv=none; b=Vplb6KwWPh1b2VeayFV17pPdBiJjfhC4MxpMZWimTnk8fkIS7NThOMSBoVwPTfTeCKoTPUEeN9sF2lHSEaZ5ZMuYBumXT2g99BK7G/chIuncCLqiMykxGbIIgNGEa7DUvShpF4XfLqNqeLLokkr6ZY7ht6g7K1bAMB8jOffIZFud6attAWNymhrmsBosUJ/YpoBFZJSOoGEI9vHnYiDxRgDme7brn2hp+B3m++qt5yjKKByBBnk1LW+SVl4qlBSbEXXNDQL/HUnSINyrXSBCSuTZFsr0u6mg9TBdPOnjZt0lx6cbgpK9UGa8VtyThNR4jUU3FFsrxShPO/vmUK9Ysg== ARC-Message-Signature: i=1; a=rsa-sha256; d=lists.ozlabs.org; s=201707; t=1781149990; c=relaxed/relaxed; bh=twBxGuT7Vyeqc2tSt+1Cu5dVnnD709Tu79Udll0+igY=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=nMbOTMYe+XS1ogxiT++NTqc4kfqB+fADNoQUh7F8dFidGIMw3cM0D+4lpr3TpGOMcqM2OxYaa/CiXrXQ6RGqyfx5+8eOYtiQaK/ZgJjzC+QnzpX6YmXPZFnuqKm5CXzL3Jnda+q3yYdsVXUpXPS1PVeoPxOk38bdMIgatzFuHpAMtQmFuOCe5AqNyR1lyVkfWHVGwVhta6qnB21bBO6AJM/ga0FQO0da7t6vmw3fb984dvWHLtGEGQt8gMk3VxdacES/1kZAa4vbD7KzzlGX4/Ma0bWK9xOk1z65HqisIUvIg/xTXmlCT2dsHv8aSjGZLPSLWXyx1F0uJPWkAZq8xw== ARC-Authentication-Results: i=1; lists.ozlabs.org; dmarc=pass (p=none dis=none) header.from=gmail.com; dkim=pass (2048-bit key; unprotected) header.d=gmail.com header.i=@gmail.com header.a=rsa-sha256 header.s=20251104 header.b=ge5oMbSx; dkim-atps=neutral; spf=pass (client-ip=2607:f8b0:4864:20::1036; helo=mail-pj1-x1036.google.com; envelope-from=rosenp@gmail.com; receiver=lists.ozlabs.org) smtp.mailfrom=gmail.com Authentication-Results: lists.ozlabs.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: lists.ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=gmail.com header.i=@gmail.com header.a=rsa-sha256 header.s=20251104 header.b=ge5oMbSx; dkim-atps=neutral Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=gmail.com (client-ip=2607:f8b0:4864:20::1036; helo=mail-pj1-x1036.google.com; envelope-from=rosenp@gmail.com; receiver=lists.ozlabs.org) Received: from mail-pj1-x1036.google.com (mail-pj1-x1036.google.com [IPv6:2607:f8b0:4864:20::1036]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange x25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4gbTJP1tt9z3brt for ; Thu, 11 Jun 2026 13:53:09 +1000 (AEST) Received: by mail-pj1-x1036.google.com with SMTP id 98e67ed59e1d1-36dac5d5d05so4008092a91.2 for ; Wed, 10 Jun 2026 20:53:08 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1781149987; x=1781754787; darn=lists.ozlabs.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=twBxGuT7Vyeqc2tSt+1Cu5dVnnD709Tu79Udll0+igY=; b=ge5oMbSxcteJSukhKuqNZkWuCZp5NGMerHgGpSiw23zXfrgbL0BO7jNsVnT6vfOU49 oQhGF42K8EKaeIk6Rfcw6Uh0zT1ZKhTmPqErZcOu/IE5QF1acZKKDTZhX6cQW66wZ88Z IGrPysHG0W+xJRd4BZ/RVtD9vDqc6ct0hD/yWXlqko87/r7VOYXy2MXsDL4jxIhL485B 6FXU3/w3J52MUL/6AWIneJPS0FE5HP0NbbUSwFPF5gpD3yrXjYMH0i4PEW8y07Hbvy0o X9BSd4M5trCVr7qe0MfJAdM5gQuOJw4/fEBQlqvy6g6oUrsSA8ljwEolR6mb408Cp3gC QQFg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1781149987; x=1781754787; 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=hdg5qBivU7ZbdkkUB1MSrIZ2odzz4XF0QAV0GlxbpWuOEUSQlg55n6yTcbColQPHU4 YI7ij6ZXW4eFI2Qf4ElNvxgxfD2iJqevBIvzQ1O1Kzv2MxSSE+TwrFzWehW7qPXz34pq j1vUwZw2PZV7ZD2nqSqYnIproGrdvNNmwvs1EFTvTosvrOaNfoMD/IKvcZ/OA8SqF6z3 ju54HbEK24KMNrZ06GR5YJWQTWDgQEqlK+y3kApGbVVvpVakkavZb4pe9O5Bz+iKvOxb YlYhWGWwRHuckZjvoHen8FcBNvjv2BUulVrHmBqWWMD/R/H5CVtKvJn8nUzcXa4DN+H4 Hxew== X-Forwarded-Encrypted: i=1; AFNElJ/Rnvr5C8ekQOD6orZ2vJHWB76IpSOBVPxosAZfKWb4YAwSSEzEgvg60pUkbBhPCdc1NpVrCTEfDw8O5GU=@lists.ozlabs.org X-Gm-Message-State: AOJu0Ywxerpj3LBl7hZsTQUBYboszW3dv6og2ioIbGnFbu/PluHVC5U8 vis01YKvDaBc9K0W6quoHpfQLZh41lxiJ7i0mZBEI2OTagIZdgaenDwS X-Gm-Gg: Acq92OFxbCfOP/1euSXVUF/EXJ19VH+okpC50MCSfGFsnoJIgJRQuoIrg2nRmSYp30v Hq3KXWlgrbdrBOAIm7A0piiohikxlUDC90Hja8ulrPJx/2+TVMQFTFir/JpIm3Me6JktpJyKi0U HKXKHLcFyx6oSC805W2tpnWiFrJxRPcXVeI8OUZPEs7leyn1bFe7eg9JRW5LQErIho4GPeYr+S9 Fxv6rRuQycgfAMci/hXAuq5vDxdejEzGux/PGQiBGKeIkQRao+xz3IkeYzfojJ1OZuSW3lSaq32 taFixdfBkXNDd2jMd+qgOEB4cJ2KBKXUVgoHgMPgGAhl91xK84IqngpI2j9DC2HY/xhWtg09oQc +jhSGAuYGX/PjPK37IyLgnVTAYzEAQLNTfdxpd2Ki5eVYkwPHiYSLzqDufDYqAk3mpmz8yv7Ai/ jHOhYx4aDtX5Gb3Kj1Z+hyBZ9tbKLoRsXZ1k04uctV5Iiy5zCr4tdadyd/80uh6y3OdsT4oOT2T Iiyrn+kM0DbIR5VdboMuqv12xVfFpEUZ2kvXMo/fvu1NA== X-Received: by 2002:a17:90b:4984:b0:36c:e254:4d5 with SMTP id 98e67ed59e1d1-3779c569455mr1233425a91.4.1781149987152; Wed, 10 Jun 2026 20:53:07 -0700 (PDT) Received: from ryzen ([2601:644:8000:5b5d:7285:c2ff:fe45:8a32]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-377522a188asm910131a91.3.2026.06.10.20.53.05 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 10 Jun 2026 20:53:06 -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: [PATCHv4 02/15] dmaengine: fsldma: drop desc_lock before invoking client callback Date: Wed, 10 Jun 2026 20:52:32 -0700 Message-ID: <20260611035245.13439-3-rosenp@gmail.com> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260611035245.13439-1-rosenp@gmail.com> References: <20260611035245.13439-1-rosenp@gmail.com> X-Mailing-List: linuxppc-dev@lists.ozlabs.org List-Id: List-Help: List-Owner: List-Post: List-Archive: , List-Subscribe: , , List-Unsubscribe: Precedence: list 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