Re: [PATCH] dmaengine: pl08x: Use kcalloc() instead of kzalloc()

From: Gustavo A. R. Silva
Date: Tue Jan 30 2024 - 13:33:42 EST




On 1/28/24 05:52, Erick Archer wrote:
This is an effort to get rid of all multiplications from allocation
functions in order to prevent integer overflows [1].

Here the multiplication is obviously safe because the "channels"
member can only be 8 or 2. This value is set when the "vendor_data"
structs are initialized.

static struct vendor_data vendor_pl080 = {
[...]
.channels = 8,
[...]
};

static struct vendor_data vendor_nomadik = {
[...]
.channels = 8,
[...]
};

static struct vendor_data vendor_pl080s = {
[...]
.channels = 8,
[...]
};

static struct vendor_data vendor_pl081 = {
[...]
.channels = 2,
[...]
};

However, using kcalloc() is more appropriate [1] and improves
readability. This patch has no effect on runtime behavior.

Link: https://github.com/KSPP/linux/issues/162 [1]
Link: https://www.kernel.org/doc/html/next/process/deprecated.html#open-coded-arithmetic-in-allocator-arguments [1]
Signed-off-by: Erick Archer <erick.archer@xxxxxxx>

Reviewed-by: Gustavo A. R. Silva <gustavoars@xxxxxxxxxx>

Thanks!
--
Gustavo

---
drivers/dma/amba-pl08x.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/dma/amba-pl08x.c b/drivers/dma/amba-pl08x.c
index eea8bd33b4b7..e40766108787 100644
--- a/drivers/dma/amba-pl08x.c
+++ b/drivers/dma/amba-pl08x.c
@@ -2855,8 +2855,8 @@ static int pl08x_probe(struct amba_device *adev, const struct amba_id *id)
}

/* Initialize physical channels */
- pl08x->phy_chans = kzalloc((vd->channels * sizeof(*pl08x->phy_chans)),
- GFP_KERNEL);
+ pl08x->phy_chans = kcalloc(vd->channels, sizeof(*pl08x->phy_chans),
+ GFP_KERNEL);
if (!pl08x->phy_chans) {
ret = -ENOMEM;
goto out_no_phychans;
--
2.25.1