[PATCH 5.4 149/202] spi: Dont mark message DMA mapped when no transfer in it is

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5.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>

[ 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@xxxxxxxxxxxxxxx>
Link: https://msgid.link/r/20240522171018.3362521-2-andriy.shevchenko@xxxxxxxxxxxxxxx
Signed-off-by: Mark Brown <broonie@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 drivers/spi/spi.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index b18ae50db1f52..0f9410ed48290 100644
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -931,6 +931,7 @@ 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) {
 		if (!ctlr->can_dma(ctlr, msg->spi, xfer))
 			continue;
@@ -954,6 +955,9 @@ 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_msg_mapped = true;
 
-- 
2.43.0







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