From: Nicolas Saenz Julienne <[email protected]>
[ Upstream commit b306320322c9cfaa465bc2c7367acf6072b1ac0e ]
With the introduction of 26751de25d25 ("spi: bcm2835: Micro-optimise
FIFO loops") it has become apparent that some users might initiate
zero-length SPI transfers. A fact the micro-optimization omitted, and
which turned out to cause crashes[1].
Instead of changing the micro-optimization itself, use a bigger hammer
and skip zero-length transfers altogether for drivers using the default
transfer_one_message() implementation.
Reported-by: Phil Elwell <[email protected]>
Fixes: 26751de25d25 ("spi: bcm2835: Micro-optimise FIFO loops")
Signed-off-by: Nicolas Saenz Julienne <[email protected]>
[1] https://github.com/raspberrypi/linux/issues/4100
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Mark Brown <[email protected]>
Signed-off-by: Sasha Levin <[email protected]>
---
drivers/spi/spi.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index 720ab34784c1d..ccca3a7409fac 100644
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -1267,7 +1267,7 @@ static int spi_transfer_one_message(struct spi_controller
*ctlr,
ptp_read_system_prets(xfer->ptp_sts);
}
- if (xfer->tx_buf || xfer->rx_buf) {
+ if ((xfer->tx_buf || xfer->rx_buf) && xfer->len) {
reinit_completion(&ctlr->xfer_completion);
fallback_pio:
--
2.27.0
