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d="scan'208";a="144082954" Received: from smtpout.microchip.com (HELO email.microchip.com) ([198.175.253.82]) by esa3.microchip.iphmx.com with ESMTP/TLS/AES256-SHA256; 16 Nov 2021 04:21:31 -0700 Received: from chn-vm-ex04.mchp-main.com (10.10.85.152) by chn-vm-ex03.mchp-main.com (10.10.85.151) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2176.14; Tue, 16 Nov 2021 04:21:29 -0700 Received: from ROB-ULT-M18064N.mchp-main.com (10.10.115.15) by chn-vm-ex04.mchp-main.com (10.10.85.152) with Microsoft SMTP Server id 15.1.2176.14 via Frontend Transport; Tue, 16 Nov 2021 04:21:25 -0700 From: Tudor Ambarus To: , , , , Subject: [PATCH 13/13] dmaengine: at_xdmac: Fix race over irq_status Date: Tue, 16 Nov 2021 13:20:36 +0200 Message-ID: <20211116112036.96349-14-tudor.ambarus@microchip.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20211116112036.96349-1-tudor.ambarus@microchip.com> References: <20211116112036.96349-1-tudor.ambarus@microchip.com> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20211116_032132_790740_6E53D163 X-CRM114-Status: GOOD ( 14.44 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: alexandre.belloni@bootlin.com, Tudor Ambarus , mripard@kernel.org, linux-kernel@vger.kernel.org, linux-serial@vger.kernel.org, dmaengine@vger.kernel.org, linux-arm-kernel@lists.infradead.org Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Tasklets run with interrupts enabled, so we need to protect atchan->irq_status with spin_lock_irq() otherwise the tasklet can be interrupted by the IRQ that modifies irq_status. While at this, rewrite at_xdmac_tasklet() so that we get rid of a level of indentation. Fixes: e1f7c9eee707 ("dmaengine: at_xdmac: creation of the atmel eXtended DMA Controller driver") Signed-off-by: Tudor Ambarus --- drivers/dma/at_xdmac.c | 80 +++++++++++++++++++----------------------- 1 file changed, 37 insertions(+), 43 deletions(-) diff --git a/drivers/dma/at_xdmac.c b/drivers/dma/at_xdmac.c index ccd6ddb12b83..082c18d45188 100644 --- a/drivers/dma/at_xdmac.c +++ b/drivers/dma/at_xdmac.c @@ -1623,6 +1623,7 @@ static void at_xdmac_handle_cyclic(struct at_xdmac_chan *atchan) dmaengine_desc_get_callback_invoke(txd, NULL); } +/* Called with atchan->lock held. */ static void at_xdmac_handle_error(struct at_xdmac_chan *atchan) { struct at_xdmac *atxdmac = to_at_xdmac(atchan->chan.device); @@ -1641,8 +1642,6 @@ static void at_xdmac_handle_error(struct at_xdmac_chan *atchan) if (atchan->irq_status & AT_XDMAC_CIS_ROIS) dev_err(chan2dev(&atchan->chan), "request overflow error!!!"); - spin_lock_irq(&atchan->lock); - /* Channel must be disabled first as it's not done automatically */ at_xdmac_write(atxdmac, AT_XDMAC_GD, atchan->mask); while (at_xdmac_read(atxdmac, AT_XDMAC_GS) & atchan->mask) @@ -1652,10 +1651,8 @@ static void at_xdmac_handle_error(struct at_xdmac_chan *atchan) struct at_xdmac_desc, xfer_node); - spin_unlock_irq(&atchan->lock); - /* Print bad descriptor's details if needed */ - dev_dbg(chan2dev(&atchan->chan), + dev_err(chan2dev(&atchan->chan), "%s: lld: mbr_sa=%pad, mbr_da=%pad, mbr_ubc=0x%08x\n", __func__, &bad_desc->lld.mbr_sa, &bad_desc->lld.mbr_da, bad_desc->lld.mbr_ubc); @@ -1665,55 +1662,52 @@ static void at_xdmac_handle_error(struct at_xdmac_chan *atchan) static void at_xdmac_tasklet(struct tasklet_struct *t) { + struct dma_async_tx_descriptor *txd; struct at_xdmac_chan *atchan = from_tasklet(atchan, t, tasklet); struct at_xdmac_desc *desc; u32 error_mask; + if (at_xdmac_chan_is_cyclic(atchan)) + return at_xdmac_handle_cyclic(atchan); + + error_mask = AT_XDMAC_CIS_RBEIS | AT_XDMAC_CIS_WBEIS | + AT_XDMAC_CIS_ROIS; + + spin_lock_irq(&atchan->lock); dev_dbg(chan2dev(&atchan->chan), "%s: status=0x%08x\n", __func__, atchan->irq_status); + if (!(atchan->irq_status & AT_XDMAC_CIS_LIS) && + !(atchan->irq_status & error_mask)) { + return spin_unlock_irq(&atchan->lock); + } - error_mask = AT_XDMAC_CIS_RBEIS - | AT_XDMAC_CIS_WBEIS - | AT_XDMAC_CIS_ROIS; - - if (at_xdmac_chan_is_cyclic(atchan)) { - at_xdmac_handle_cyclic(atchan); - } else if ((atchan->irq_status & AT_XDMAC_CIS_LIS) - || (atchan->irq_status & error_mask)) { - struct dma_async_tx_descriptor *txd; - - if (atchan->irq_status & error_mask) - at_xdmac_handle_error(atchan); - - spin_lock_irq(&atchan->lock); - desc = list_first_entry(&atchan->xfers_list, - struct at_xdmac_desc, - xfer_node); - dev_vdbg(chan2dev(&atchan->chan), "%s: desc 0x%p\n", __func__, desc); - if (!desc->active_xfer) { - dev_err(chan2dev(&atchan->chan), "Xfer not active: exiting"); - spin_unlock_irq(&atchan->lock); - return; - } + if (atchan->irq_status & error_mask) + at_xdmac_handle_error(atchan); - txd = &desc->tx_dma_desc; - dma_cookie_complete(txd); - /* Remove the transfer from the transfer list. */ - list_del(&desc->xfer_node); - spin_unlock_irq(&atchan->lock); + desc = list_first_entry(&atchan->xfers_list, struct at_xdmac_desc, + xfer_node); + dev_vdbg(chan2dev(&atchan->chan), "%s: desc 0x%p\n", __func__, desc); + if (!desc->active_xfer) { + dev_err(chan2dev(&atchan->chan), "Xfer not active: exiting"); + return spin_unlock_irq(&atchan->lock); + } - if (txd->flags & DMA_PREP_INTERRUPT) - dmaengine_desc_get_callback_invoke(txd, NULL); + txd = &desc->tx_dma_desc; + dma_cookie_complete(txd); + /* Remove the transfer from the transfer list. */ + list_del(&desc->xfer_node); + spin_unlock_irq(&atchan->lock); - dma_run_dependencies(txd); + if (txd->flags & DMA_PREP_INTERRUPT) + dmaengine_desc_get_callback_invoke(txd, NULL); - spin_lock_irq(&atchan->lock); - /* Move the xfer descriptors into the free descriptors list. */ - list_splice_tail_init(&desc->descs_list, - &atchan->free_descs_list); - at_xdmac_advance_work(atchan); - spin_unlock_irq(&atchan->lock); - } + dma_run_dependencies(txd); + + spin_lock_irq(&atchan->lock); + /* Move the xfer descriptors into the free descriptors list. */ + list_splice_tail_init(&desc->descs_list, &atchan->free_descs_list); + at_xdmac_advance_work(atchan); + spin_unlock_irq(&atchan->lock); } static irqreturn_t at_xdmac_interrupt(int irq, void *dev_id)