[PATCH 6.9 286/374] spi: Dont mark message DMA mapped when no transfer in it is

Greg Kroah-Hartman
2024-06-06T14:10:48Z

From: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

[ Upstream commit 9f788ba457b45b0ce422943fcec9fa35c4587764 ]

There is no need to set the DMA mapped flag of the message if it has
no mapped transfers. Moreover, it may give the code a chance to take
the wrong paths, i.e. to exercise DMA related APIs on unmapped data.
Make __spi_map_msg() to bail earlier on the above mentioned cases.

Fixes: 99adef310f68 ("spi: Provide core support for DMA mapping transfers")
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://msgid.link/r/20240522171018.3362521-2-andriy.shevchenko@linux.intel.com
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/spi/spi.c | 4 ++++
1 file changed, 4 insertions(+)

diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index a2c467d9e92f5..2cea7aeb10f95 100644
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -1242,6 +1242,7 @@ static int __spi_map_msg(struct spi_controller *ctlr, struct spi_message *msg)
else
rx_dev = ctlr->dev.parent;

+ ret = -ENOMSG;
list_for_each_entry(xfer, &msg->transfers, transfer_list) {
/* The sync is done before each transfer. */
unsigned long attrs = DMA_ATTR_SKIP_CPU_SYNC;
@@ -1271,6 +1272,9 @@ static int __spi_map_msg(struct spi_controller *ctlr, struct spi_message *msg)
}
}
}
+ /* No transfer has been mapped, bail out with success */
+ if (ret)
+ return 0;

ctlr->cur_rx_dma_dev = rx_dev;
ctlr->cur_tx_dma_dev = tx_dev;
--
2.43.0