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authorLukas Wunner <lukas@wunner.de>2018-11-08 08:06:10 +0100
committerMark Brown <broonie@kernel.org>2018-11-28 15:42:50 +0000
commite82b0b3828451c1cd331d9f304c6078fcd43b62e (patch)
treeebf9a84125a4407096f6c2298fac764626f40356 /drivers/spi
parentdbc944115eed48af110646992893dc43321368d8 (diff)
spi: bcm2835: Fix race on DMA termination
If a DMA transfer finishes orderly right when spi_transfer_one_message() determines that it has timed out, the callbacks bcm2835_spi_dma_done() and bcm2835_spi_handle_err() race to call dmaengine_terminate_all(), potentially leading to double termination. Prevent by atomically changing the dma_pending flag before calling dmaengine_terminate_all(). Signed-off-by: Lukas Wunner <lukas@wunner.de> Fixes: 3ecd37edaa2a ("spi: bcm2835: enable dma modes for transfers meeting certain conditions") Cc: stable@vger.kernel.org # v4.2+ Cc: Mathias Duckeck <m.duckeck@kunbus.de> Cc: Frank Pavlic <f.pavlic@kunbus.de> Cc: Martin Sperl <kernel@martin.sperl.org> Cc: Noralf Trønnes <noralf@tronnes.org> Signed-off-by: Mark Brown <broonie@kernel.org>
Diffstat (limited to 'drivers/spi')
-rw-r--r--drivers/spi/spi-bcm2835.c10
1 files changed, 4 insertions, 6 deletions
diff --git a/drivers/spi/spi-bcm2835.c b/drivers/spi/spi-bcm2835.c
index 594e9712ecbc..774161bbcb2e 100644
--- a/drivers/spi/spi-bcm2835.c
+++ b/drivers/spi/spi-bcm2835.c
@@ -232,10 +232,9 @@ static void bcm2835_spi_dma_done(void *data)
* is called the tx-dma must have finished - can't get to this
* situation otherwise...
*/
- dmaengine_terminate_all(master->dma_tx);
-
- /* mark as no longer pending */
- bs->dma_pending = 0;
+ if (cmpxchg(&bs->dma_pending, true, false)) {
+ dmaengine_terminate_all(master->dma_tx);
+ }
/* and mark as completed */;
complete(&master->xfer_completion);
@@ -617,10 +616,9 @@ static void bcm2835_spi_handle_err(struct spi_master *master,
struct bcm2835_spi *bs = spi_master_get_devdata(master);
/* if an error occurred and we have an active dma, then terminate */
- if (bs->dma_pending) {
+ if (cmpxchg(&bs->dma_pending, true, false)) {
dmaengine_terminate_all(master->dma_tx);
dmaengine_terminate_all(master->dma_rx);
- bs->dma_pending = 0;
}
/* and reset */
bcm2835_spi_reset_hw(master);

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