From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=204.191.154.188 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794332553; b=VnO8A3Q6NCnywMzy5Lv3JtWDXzTGSArl058AEcFXOQh4Nc7rvQZHa7ysJ07Tg93ccgw3 RkRJuCLeZqpKWNALb9GPW/etoNMBTs1GgVCM37kmBOK6J4QiN70Uzkn7gfj5fG0TGHhgU RUq7MdipbMUagA+NyZZgLzjbKXL6lEiGP5zQ5jVv+p4pLYrFVYSVYxAYKDgXpm08nvczy k2SF7t7F9xgjeQab0si4fgvgtPpZl23GtBOUXblVzySj3TsAbfrlLw8pGBSmBzA9UY6/P Oj+zw8dX1yyR/4pWuJdALlNBStEeCKCqSXyah7iLDUZ5sl1XifYBTh1tChXwmTu6i8Q== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794332553; h=DMARC-Filter:DKIM-Signature:Received:Received:From:To:Cc:Date: Message-ID:X-Mailer:In-Reply-To:References:MIME-Version: Content-Transfer-Encoding:X-SA-Exim-Connect-IP:X-SA-Exim-Rcpt-To: X-SA-Exim-Mail-From:X-Spam-Checker-Version:X-Spam-Level:X-Spam-Status: Subject:X-SA-Exim-Version:X-SA-Exim-Scanned; bh=6hRmAt6Nv9zxg/FdmenP+WtbZJVt2hCdxtlI/zHA/a4=; b=i7PaM9TbCj1qOsp2mL/jpkRgwYrNxZ9VVdOd2dFEKhqxLXc2cnmljrVeDJXQ3nz5Kv5j PE6BonQ6Ar1rPxGKKJwYf5r6nqcwI8XIApltmdlZ+H3LeXFkViJnIaV7Exj/MvUl68ME3 r2bV8l6Jb/ZStSqQ4iv9PCTZQkbjAfZlXakmytUT3k/JP1VltFFo0T/jG8Pk53wYNONwz 2SIRHR4M0Yh1tQV6r4AKCi9xdUPG+zMUKcEc5IzAG6U2XmhpvplUaT5BGQlXG44ZGY1ol +5hC8Iaa55744WnNmZOWHHI8ZVmaOAt2wGtmvKeojeokQ8k0Ke5hSK7lPCp7Df27f1Q== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass header.from=deltatee.com; spf=pass smtp.mailfrom=deltatee.com; dkim=pass header.d=deltatee.com header.i=@deltatee.com header.a=rsa-sha256 header.s=20200525 header.b=rte3d+7V; arc=none smtp.remote-ip=204.191.154.188 Received: from ale.deltatee.com (ale.deltatee.com [204.191.154.188]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange ECDHE (prime256v1) server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 63E6560A262D; Tue, 10 Nov 2026 17:42:33 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org 63E6560A262D Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=deltatee.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=deltatee.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=deltatee.com header.i=@deltatee.com header.a=rsa-sha256 header.s=20200525 header.b=rte3d+7V DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=deltatee.com; s=20200525; h=Subject:MIME-Version:References:In-Reply-To: Message-ID:Date:Cc:To:From:content-disposition; bh=6hRmAt6Nv9zxg/FdmenP+WtbZJVt2hCdxtlI/zHA/a4=; b=rte3d+7V7ASTFLmYzha/MPz6Og BTsBcm16K02zDwHx8K+R5XPSTJGx7nIuJPy2GTgXLHJqYFRPJb+JyYIhu2snFHe/68dvkGUDq7ugd FeLBZE+pGkUgdAG7uWcwoDnIwQC5i6teAf61Ce9i7TVSQdef1wX41hLpFdpIROhzOZqZ2HH7axio1 72jTP8nLgmE7jWYvuly6eW+xcph45yWg3XEIwMG0x66ABGYa8WSHrnVALrPTcFfI67ukjycwuisZ9 Utt42FYR4ZXfBF0VzMil7d8MUY/+EZNz/Og9YCuMZJkzPOoMQpQcP9JeAB2uAYcpJwMXTIZHV0rpN mufPtP3Q==; Received: from donard.priv.deltatee.com ([172.16.1.31]) by ale.deltatee.com with esmtps (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.98.2) (envelope-from ) id 1xQprb-00000000o8S-2esx; Tue, 10 Nov 2026 11:42:32 -0600 Received: from logang by donard.priv.deltatee.com with local (Exim 4.98.2) (envelope-from ) id 1xQpqg-00000002cVv-3aW6; Tue, 10 Nov 2026 11:41:34 -0600 From: Logan Gunthorpe To: dmaengine@vger.kernel.org, linux-kernel@vger.kernel.org, Vinod Koul Cc: Frank Li , Logan Gunthorpe , Sashiko Date: Tue, 10 Nov 2026 11:39:27 -0600 Message-ID: <20261110173927.624629-7-logang@deltatee.com> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20261110173927.624629-1-logang@deltatee.com> References: <20261110173927.624629-1-logang@deltatee.com> X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-SA-Exim-Connect-IP: 172.16.1.31 X-SA-Exim-Rcpt-To: dmaengine@vger.kernel.org, linux-kernel@vger.kernel.org, Frank.li@nxp.com, logang@deltatee.com, vkoul@kernel.org, sashiko-bot@kernel.org X-SA-Exim-Mail-From: logang@deltatee.com X-Spam-Level: Subject: [PATCH v2 6/6] dmaengine: plx_dma: don't invoke client callbacks with ring_lock held X-SA-Exim-Version: 4.2.1 (built Sun, 23 Feb 2025 07:57:16 +0000) X-SA-Exim-Scanned: Yes (on ale.deltatee.com) plx_dma_process_desc() and plx_dma_abort_desc() invoke the client's completion callback with ring_lock held. A callback that submits a new transfer, which is common, deadlocks taking the same lock in plx_dma_prep_memcpy(). Copy and clear the callback and advance tail under ring_lock, then drop it to invoke the callback. To keep callbacks in order and ensure plx_dma_free_chan_resources() can't return while one is still running from plx_dma_remove(), serialize completion with a new complete_lock held across the whole loop. plx_dma_tx_status() only trylocks it, so a callback that polls the channel won't deadlock. Reported-by: Sashiko Link: https://lore.kernel.org/dmaengine/20260717223217.B6FBF1F000E9@smtp.kernel.org Signed-off-by: Logan Gunthorpe --- drivers/dma/plx_dma.c | 45 ++++++++++++++++++++++++++++++++++++------- 1 file changed, 38 insertions(+), 7 deletions(-) diff --git a/drivers/dma/plx_dma.c b/drivers/dma/plx_dma.c index d1bdff1b7310..394ca5483434 100644 --- a/drivers/dma/plx_dma.c +++ b/drivers/dma/plx_dma.c @@ -108,6 +108,8 @@ struct plx_dma_dev { void __iomem *bar; struct tasklet_struct desc_task; + /* serializes descriptor completion and callback invocation */ + spinlock_t complete_lock; spinlock_t ring_lock; bool ring_active; int head; @@ -132,12 +134,15 @@ static struct plx_dma_desc *plx_dma_get_desc(struct plx_dma_dev *plxdev, int i) return plxdev->desc_ring[i & (PLX_DMA_RING_COUNT - 1)]; } -static void plx_dma_process_desc(struct plx_dma_dev *plxdev) +static void plx_dma_process_desc_unlocked(struct plx_dma_dev *plxdev) { + struct dmaengine_desc_callback cb; struct dmaengine_result res; struct plx_dma_desc *desc; u32 flags; + lockdep_assert_held(&plxdev->complete_lock); + spin_lock_bh(&plxdev->ring_lock); while (plxdev->tail != plxdev->head) { @@ -166,22 +171,35 @@ static void plx_dma_process_desc(struct plx_dma_dev *plxdev) dma_cookie_complete(&desc->txd); dma_descriptor_unmap(&desc->txd); - dmaengine_desc_get_callback_invoke(&desc->txd, &res); + dmaengine_desc_get_callback(&desc->txd, &cb); desc->txd.callback = NULL; desc->txd.callback_result = NULL; - plxdev->tail++; + + spin_unlock_bh(&plxdev->ring_lock); + dmaengine_desc_callback_invoke(&cb, &res); + spin_lock_bh(&plxdev->ring_lock); } spin_unlock_bh(&plxdev->ring_lock); } +static void plx_dma_process_desc(struct plx_dma_dev *plxdev) +{ + spin_lock_bh(&plxdev->complete_lock); + plx_dma_process_desc_unlocked(plxdev); + spin_unlock_bh(&plxdev->complete_lock); +} + static void plx_dma_abort_desc(struct plx_dma_dev *plxdev) { + struct dmaengine_desc_callback cb; struct dmaengine_result res; struct plx_dma_desc *desc; - plx_dma_process_desc(plxdev); + spin_lock_bh(&plxdev->complete_lock); + + plx_dma_process_desc_unlocked(plxdev); spin_lock_bh(&plxdev->ring_lock); @@ -193,14 +211,18 @@ static void plx_dma_abort_desc(struct plx_dma_dev *plxdev) dma_cookie_complete(&desc->txd); dma_descriptor_unmap(&desc->txd); - dmaengine_desc_get_callback_invoke(&desc->txd, &res); + dmaengine_desc_get_callback(&desc->txd, &cb); desc->txd.callback = NULL; desc->txd.callback_result = NULL; - plxdev->tail++; + + spin_unlock_bh(&plxdev->ring_lock); + dmaengine_desc_callback_invoke(&cb, &res); + spin_lock_bh(&plxdev->ring_lock); } spin_unlock_bh(&plxdev->ring_lock); + spin_unlock_bh(&plxdev->complete_lock); } static void __plx_dma_stop(struct plx_dma_dev *plxdev) @@ -337,7 +359,15 @@ static enum dma_status plx_dma_tx_status(struct dma_chan *chan, if (ret == DMA_COMPLETE) return ret; - plx_dma_process_desc(plxdev); + /* + * If another context is already completing descriptors (possibly + * a callback on this CPU that is polling the channel), let it + * finish rather than waiting on it. + */ + if (spin_trylock_bh(&plxdev->complete_lock)) { + plx_dma_process_desc_unlocked(plxdev); + spin_unlock_bh(&plxdev->complete_lock); + } return dma_cookie_status(chan, cookie, txstate); } @@ -518,6 +548,7 @@ static int plx_dma_create(struct pci_dev *pdev) if (!plxdev) return -ENOMEM; + spin_lock_init(&plxdev->complete_lock); spin_lock_init(&plxdev->ring_lock); tasklet_setup(&plxdev->desc_task, plx_dma_desc_task); -- 2.47.3