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Thu, 23 Jan 2020 14:03:17 +0000 From: To: , , CC: , , Subject: [PATCH 10/10] dmaengine: at_xdmac: Fix locking in tasklet Thread-Topic: [PATCH 10/10] dmaengine: at_xdmac: Fix locking in tasklet Thread-Index: AQHV0fXcFbXcnKYrSE6o/6h9ErutqQ== Date: Thu, 23 Jan 2020 14:03:17 +0000 Message-ID: <20200123140237.125799-10-tudor.ambarus@microchip.com> References: <20200123140237.125799-1-tudor.ambarus@microchip.com> In-Reply-To: <20200123140237.125799-1-tudor.ambarus@microchip.com> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [94.177.32.156] x-ms-publictraffictype: Email x-ms-office365-filtering-correlation-id: 87a3c654-dff5-46b4-a5ea-08d7a00cff19 x-ms-traffictypediagnostic: MN2PR11MB3582: x-ms-exchange-transport-forked: True x-microsoft-antispam-prvs: x-ms-oob-tlc-oobclassifiers: OLM:3044; x-forefront-prvs: 029174C036 x-forefront-antispam-report: SFV:NSPM;SFS:(10009020)(376002)(346002)(396003)(366004)(39860400002)(136003)(189003)(199004)(2616005)(6486002)(316002)(26005)(36756003)(4326008)(81156014)(186003)(54906003)(110136005)(81166006)(6512007)(5660300002)(478600001)(8676002)(66946007)(64756008)(66476007)(76116006)(91956017)(66446008)(66556008)(1076003)(2906002)(6506007)(107886003)(8936002)(71200400001)(86362001);DIR:OUT;SFP:1101;SCL:1;SRVR:MN2PR11MB3582;H:MN2PR11MB4448.namprd11.prod.outlook.com;FPR:;SPF:None;LANG:en;PTR:InfoNoRecords;MX:1;A:1; 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This means that we should replace all the (already present) spin_lock_irqsave() uses in the tasklet with spin_lock_irq() to protect being interrupted by a IRQ which tries to get the same lock (via calls to device_prep_dma_* for example). spin_lock and spin_lock_bh in tasklets are not enough to protect from IRQs, update these to spin_lock_irq(). at_xdmac_advance_work() can be called with all the interrupts enabled (when called from tasklet), or with interrupts disabled (when called from at_xdmac_issue_pending). Move the locking in the callers to be able to use spin_lock_irq() and spin_lock_irqsave() for these cases. Signed-off-by: Tudor Ambarus --- drivers/dma/at_xdmac.c | 23 ++++++++++++----------- 1 file changed, 12 insertions(+), 11 deletions(-) diff --git a/drivers/dma/at_xdmac.c b/drivers/dma/at_xdmac.c index 31321da69ae6..bb0eaf38b594 100644 --- a/drivers/dma/at_xdmac.c +++ b/drivers/dma/at_xdmac.c @@ -1543,9 +1543,6 @@ static void at_xdmac_remove_xfer(struct at_xdmac_chan *atchan, static void at_xdmac_advance_work(struct at_xdmac_chan *atchan) { struct at_xdmac_desc *desc; - unsigned long flags; - - spin_lock_irqsave(&atchan->lock, flags); /* * If channel is enabled, do nothing, advance_work will be triggered @@ -1559,8 +1556,6 @@ static void at_xdmac_advance_work(struct at_xdmac_chan *atchan) if (!desc->active_xfer) at_xdmac_start_xfer(atchan, desc); } - - spin_unlock_irqrestore(&atchan->lock, flags); } static void at_xdmac_handle_cyclic(struct at_xdmac_chan *atchan) @@ -1596,7 +1591,7 @@ 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_bh(&atchan->lock); + 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); @@ -1607,7 +1602,7 @@ static void at_xdmac_handle_error(struct at_xdmac_chan *atchan) struct at_xdmac_desc, xfer_node); - spin_unlock_bh(&atchan->lock); + spin_unlock_irq(&atchan->lock); /* Print bad descriptor's details if needed */ dev_dbg(chan2dev(&atchan->chan), @@ -1640,21 +1635,21 @@ static void at_xdmac_tasklet(unsigned long data) if (atchan->irq_status & error_mask) at_xdmac_handle_error(atchan); - spin_lock(&atchan->lock); + 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(&atchan->lock); + spin_unlock_irq(&atchan->lock); return; } txd = &desc->tx_dma_desc; at_xdmac_remove_xfer(atchan, desc); - spin_unlock(&atchan->lock); + spin_unlock_irq(&atchan->lock); dma_cookie_complete(txd); if (txd->flags & DMA_PREP_INTERRUPT) @@ -1662,7 +1657,9 @@ static void at_xdmac_tasklet(unsigned long data) dma_run_dependencies(txd); + spin_lock_irq(&atchan->lock); at_xdmac_advance_work(atchan); + spin_unlock_irq(&atchan->lock); } } @@ -1723,11 +1720,15 @@ static irqreturn_t at_xdmac_interrupt(int irq, void *dev_id) static void at_xdmac_issue_pending(struct dma_chan *chan) { struct at_xdmac_chan *atchan = to_at_xdmac_chan(chan); + unsigned long flags; dev_dbg(chan2dev(&atchan->chan), "%s\n", __func__); - if (!at_xdmac_chan_is_cyclic(atchan)) + if (!at_xdmac_chan_is_cyclic(atchan)) { + spin_lock_irqsave(&atchan->lock, flags); at_xdmac_advance_work(atchan); + spin_unlock_irqrestore(&atchan->lock, flags); + } return; }