[PATCH v2] spi: microchip-core: fix passing zero to PTR_ERR warning

[PATCH v2] spi: microchip-core: fix passing zero to PTR_ERR warning

[Conor Dooley]

It is possible that the error case for devm_clk_get() returns NULL,
in which case zero will be passed to PTR_ERR() as shown by the Smatch
static checker warning:
drivers/spi/spi-microchip-core.c:557 mchp_corespi_probe()
warn: passing zero to 'PTR_ERR'

Remove the NULL check and carry on with a dummy clock in case of an
error. To avoid a potential div zero, abort calculating clkgen if
clk_get_rate(spi->clk) is zero.

Fixes: 9ac8d17694b6 ("spi: add support for microchip fpga spi controllers")
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Link: https://lore.kernel.org/linux-spi/20220615091633.GI2168@kadam/
Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
---
v2: drop the NULL check entirely rather than returning -ENXIO if NULL
---
 drivers/spi/spi-microchip-core.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/spi/spi-microchip-core.c b/drivers/spi/spi-microchip-core.c
index 5b2aee30fa04..d866a831104c 100644
--- a/drivers/spi/spi-microchip-core.c
+++ b/drivers/spi/spi-microchip-core.c
@@ -433,6 +433,8 @@ static int mchp_corespi_calculate_clkgen(struct mchp_corespi *spi,
 	unsigned long clk_hz, spi_hz, clk_gen;
 
 	clk_hz = clk_get_rate(spi->clk);
+	if (!clk_hz)
+		return -EINVAL;
 	spi_hz = min(target_hz, clk_hz);
 
 	/*
@@ -553,7 +555,7 @@ static int mchp_corespi_probe(struct platform_device *pdev)
 	}
 
 	spi->clk = devm_clk_get(&pdev->dev, NULL);
-	if (!spi->clk || IS_ERR(spi->clk)) {
+	if (IS_ERR(spi->clk)) {
 		ret = PTR_ERR(spi->clk);
 		dev_err(&pdev->dev, "could not get clk: %d\n", ret);
 		goto error_release_master;
-- 
2.36.1

Re: [PATCH v2] spi: microchip-core: fix passing zero to PTR_ERR warning

[Mark Brown]

On Wed, 15 Jun 2022 15:20:29 +0100, Conor Dooley wrote:
> It is possible that the error case for devm_clk_get() returns NULL,
> in which case zero will be passed to PTR_ERR() as shown by the Smatch
> static checker warning:
> drivers/spi/spi-microchip-core.c:557 mchp_corespi_probe()
> warn: passing zero to 'PTR_ERR'
> 
> Remove the NULL check and carry on with a dummy clock in case of an
> error. To avoid a potential div zero, abort calculating clkgen if
> clk_get_rate(spi->clk) is zero.
> 
> [...]

Applied to

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

Thanks!

[1/1] spi: microchip-core: fix passing zero to PTR_ERR warning
      commit: 2081ad1467469b649fc9f9226b235977a7bf9402

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