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spi: bcm2835: Fix race on DMA termination

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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: 3ecd37edaa ("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>
This commit is contained in:
Lukas Wunner 2018-11-08 08:06:10 +01:00 committed by Mark Brown
parent dbc944115e
commit e82b0b3828
No known key found for this signature in database
GPG Key ID: 24D68B725D5487D0
1 changed files with 4 additions and 6 deletions
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10
drivers/spi/spi-bcm2835.c
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@ -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);