[PATCH v1 1/1] spi: topcliff-pch: Prevent usage of potentially stale DMA device

[PATCH v1 1/1] spi: topcliff-pch: Prevent usage of potentially stale DMA device

[Andy Shevchenko]

DMA device is expected to be available while SPI transfer is ongoing.

Prevent usage of potentially stale DMA device by keeping reference
count till the end of the transfer.

Fixes: 4d986ffa036a ("spi: add missing pci_dev_put() before return")
Reported-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
---
 drivers/spi/spi-topcliff-pch.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/spi/spi-topcliff-pch.c b/drivers/spi/spi-topcliff-pch.c
index 8e1cc345810a..dfaa1d79a78b 100644
--- a/drivers/spi/spi-topcliff-pch.c
+++ b/drivers/spi/spi-topcliff-pch.c
@@ -103,6 +103,7 @@
 static int use_dma = 1;
 
 struct pch_spi_dma_ctrl {
+	struct pci_dev		*dma_dev;
 	struct dma_async_tx_descriptor	*desc_tx;
 	struct dma_async_tx_descriptor	*desc_rx;
 	struct pch_dma_slave		param_tx;
@@ -876,7 +877,6 @@ static void pch_spi_request_dma(struct pch_spi_data *data, int bpw)
 	if (!chan) {
 		dev_err(&data->master->dev,
 			"ERROR: dma_request_channel FAILS(Tx)\n");
-		data->use_dma = 0;
 		goto out;
 	}
 	dma->chan_tx = chan;
@@ -893,13 +893,15 @@ static void pch_spi_request_dma(struct pch_spi_data *data, int bpw)
 			"ERROR: dma_request_channel FAILS(Rx)\n");
 		dma_release_channel(dma->chan_tx);
 		dma->chan_tx = NULL;
-		data->use_dma = 0;
 		goto out;
 	}
 	dma->chan_rx = chan;
 
+	dma->dma_dev = dma_dev;
+	return;
 out:
 	pci_dev_put(dma_dev);
+	data->use_dma = 0;
 }
 
 static void pch_spi_release_dma(struct pch_spi_data *data)
@@ -915,6 +917,8 @@ static void pch_spi_release_dma(struct pch_spi_data *data)
 		dma_release_channel(dma->chan_rx);
 		dma->chan_rx = NULL;
 	}
+
+	pci_dev_put(dma->dma_dev);
 }
 
 static void pch_spi_handle_dma(struct pch_spi_data *data, int *bpw)
-- 
2.34.1

Re: [PATCH v1 1/1] spi: topcliff-pch: Prevent usage of potentially stale DMA device

[Mark Brown]

On Mon, 7 Mar 2022 19:37:40 +0200, Andy Shevchenko wrote:
> DMA device is expected to be available while SPI transfer is ongoing.
> 
> Prevent usage of potentially stale DMA device by keeping reference
> count till the end of the transfer.
> 
> 

Applied to

   https://git.kernel.org/pub/scm/linux/kernel/git/broonie/spi.git for-next

Thanks!

[1/1] spi: topcliff-pch: Prevent usage of potentially stale DMA device
      commit: 80ab9012bbf1011f57c06b3c6e4ac3816c4a86f5

All being well this means that it will be integrated into the linux-next
tree (usually sometime in the next 24 hours) and sent to Linus during
the next merge window (or sooner if it is a bug fix), however if
problems are discovered then the patch may be dropped or reverted.

You may get further e-mails resulting from automated or manual testing
and review of the tree, please engage with people reporting problems and
send followup patches addressing any issues that are reported if needed.

If any updates are required or you are submitting further changes they
should be sent as incremental updates against current git, existing
patches will not be replaced.

Please add any relevant lists and maintainers to the CCs when replying
to this mail.

Thanks,
Mark