2020-11-02 10:58:31

by Geert Uytterhoeven

Subject: [PATCH] of: Drop superfluous ULL suffix for ~0

There is no need to specify a "ULL" suffix for "all bits set": "~0" is
sufficient, and works regardless of type. In fact adding the suffix
makes the code more fragile.

Fixes: 48ab6d5d1f096d6f ("dma-mapping: fix 32-bit overflow with CONFIG_ARM_LPAE=n")
Suggested-by: Linus Torvalds <[email protected]>
Signed-off-by: Geert Uytterhoeven <[email protected]>
---
drivers/of/device.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/of/device.c b/drivers/of/device.c
index 3a469c79e6b05de4..aedfaaafd3e7edb7 100644
--- a/drivers/of/device.c
+++ b/drivers/of/device.c
@@ -112,7 +112,7 @@ int of_dma_configure_id(struct device *dev, struct device_node *np,
u64 dma_end = 0;

/* Determine the overall bounds of all DMA regions */
- for (dma_start = ~0ULL; r->size; r++) {
+ for (dma_start = ~0; r->size; r++) {
/* Take lower and upper limits */
if (r->dma_start < dma_start)
dma_start = r->dma_start;
--
2.25.1

2020-11-02 17:37:10

by Linus Torvalds

Subject: Re: [PATCH] of: Drop superfluous ULL suffix for ~0

On Mon, Nov 2, 2020 at 2:54 AM Geert Uytterhoeven
<[email protected]> wrote:
>
> There is no need to specify a "ULL" suffix for "all bits set": "~0" is
> sufficient, and works regardless of type. In fact adding the suffix
> makes the code more fragile.

I took this directly, since it was triggered by my code pattern rant.

Thanks,
Linus