4.4-stable review patch. If anyone has any objections, please let me know.
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From: Lukas Wunner lukas@wunner.de
commit e82b0b3828451c1cd331d9f304c6078fcd43b62e upstream.
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 Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/spi/spi-bcm2835.c | 10 ++++------ 1 file changed, 4 insertions(+), 6 deletions(-)
--- a/drivers/spi/spi-bcm2835.c +++ b/drivers/spi/spi-bcm2835.c @@ -233,10 +233,9 @@ static void bcm2835_spi_dma_done(void *d * 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(struc 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);