From: Nicolas Saenz Julienne nsaenzjulienne@suse.de
[ 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 phil@raspberrypi.com Fixes: 26751de25d25 ("spi: bcm2835: Micro-optimise FIFO loops") Signed-off-by: Nicolas Saenz Julienne nsaenzjulienne@suse.de
[1] https://github.com/raspberrypi/linux/issues/4100 Link: https://lore.kernel.org/r/20210211180820.25757-1-nsaenzjulienne@suse.de
Signed-off-by: Mark Brown broonie@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- 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 7694e1ae5b0b2..4257a2d368f71 100644 --- a/drivers/spi/spi.c +++ b/drivers/spi/spi.c @@ -1259,7 +1259,7 @@ 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: