[PATCH] IB/mlx5: Fix a parameter of find_first_bit

[PATCH] IB/mlx5: Fix a parameter of find_first_bit

[Christophe JAILLET]

The 2nd parameter of 'find_first_bit' is the number of bits to search.
In this case, we are passing 'sizeof(tmp)' which is likely to be 4 or 8
because 'tmp' is an 'unsigned long'.

It is likely that the number of bits of 'tmp' was expected here. So use
BITS_PER_LONG instead.

It has been spotted by the following coccinelle script:
@@
expression ret, x;

@@
*  ret = \(find_first_bit \| find_first_zero_bit\) (x, sizeof(...));

Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
---
__ffs could be used to reduce code verbosity
---
 drivers/infiniband/hw/mlx5/mem.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/infiniband/hw/mlx5/mem.c b/drivers/infiniband/hw/mlx5/mem.c
index 40df2cca0609..996b54e366b0 100644
--- a/drivers/infiniband/hw/mlx5/mem.c
+++ b/drivers/infiniband/hw/mlx5/mem.c
@@ -71,7 +71,7 @@ void mlx5_ib_cont_pages(struct ib_umem *umem, u64 addr, int *count, int *shift,
 
 	addr = addr >> page_shift;
 	tmp = (unsigned long)addr;
-	m = find_first_bit(&tmp, sizeof(tmp));
+	m = find_first_bit(&tmp, BITS_PER_LONG);
 	skip = 1 << m;
 	mask = skip - 1;
 	i = 0;
@@ -81,7 +81,7 @@ void mlx5_ib_cont_pages(struct ib_umem *umem, u64 addr, int *count, int *shift,
 		for (k = 0; k < len; k++) {
 			if (!(i & mask)) {
 				tmp = (unsigned long)pfn;
-				m = min_t(unsigned long, m, find_first_bit(&tmp, sizeof(tmp)));
+				m = min_t(unsigned long, m, find_first_bit(&tmp, BITS_PER_LONG));
 				skip = 1 << m;
 				mask = skip - 1;
 				base = pfn;
@@ -89,7 +89,7 @@ void mlx5_ib_cont_pages(struct ib_umem *umem, u64 addr, int *count, int *shift,
 			} else {
 				if (base + p != pfn) {
 					tmp = (unsigned long)p;
-					m = find_first_bit(&tmp, sizeof(tmp));
+					m = find_first_bit(&tmp, BITS_PER_LONG);
 					skip = 1 << m;
 					mask = skip - 1;
 					base = pfn;
-- 
2.7.4


---
L'absence de virus dans ce courrier électronique a été vérifiée par le logiciel antivirus Avast.
https://www.avast.com/antivirus

Re: [PATCH] IB/mlx5: Fix a parameter of find_first_bit

[Majd Dibbiny]

Acked-by: Majd Dibbiny <majd@mellanox.com>

> On Aug 26, 2016, at 8:25 AM, Christophe JAILLET <christophe.jaillet@wanadoo.fr> wrote:
> 
> The 2nd parameter of 'find_first_bit' is the number of bits to search.
> In this case, we are passing 'sizeof(tmp)' which is likely to be 4 or 8
> because 'tmp' is an 'unsigned long'.
> 
> It is likely that the number of bits of 'tmp' was expected here. So use
> BITS_PER_LONG instead.
> 
> It has been spotted by the following coccinelle script:
> @@
> expression ret, x;
> 
> @@
> *  ret = \(find_first_bit \| find_first_zero_bit\) (x, sizeof(...));
> 
> Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
> ---
> __ffs could be used to reduce code verbosity
> ---
> drivers/infiniband/hw/mlx5/mem.c | 6 +++---
> 1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/infiniband/hw/mlx5/mem.c b/drivers/infiniband/hw/mlx5/mem.c
> index 40df2cca0609..996b54e366b0 100644
> --- a/drivers/infiniband/hw/mlx5/mem.c
> +++ b/drivers/infiniband/hw/mlx5/mem.c
> @@ -71,7 +71,7 @@ void mlx5_ib_cont_pages(struct ib_umem *umem, u64 addr, int *count, int *shift,
> 
>    addr = addr >> page_shift;
>    tmp = (unsigned long)addr;
> -    m = find_first_bit(&tmp, sizeof(tmp));
> +    m = find_first_bit(&tmp, BITS_PER_LONG);
>    skip = 1 << m;
>    mask = skip - 1;
>    i = 0;
> @@ -81,7 +81,7 @@ void mlx5_ib_cont_pages(struct ib_umem *umem, u64 addr, int *count, int *shift,
>        for (k = 0; k < len; k++) {
>            if (!(i & mask)) {
>                tmp = (unsigned long)pfn;
> -                m = min_t(unsigned long, m, find_first_bit(&tmp, sizeof(tmp)));
> +                m = min_t(unsigned long, m, find_first_bit(&tmp, BITS_PER_LONG));
>                skip = 1 << m;
>                mask = skip - 1;
>                base = pfn;
> @@ -89,7 +89,7 @@ void mlx5_ib_cont_pages(struct ib_umem *umem, u64 addr, int *count, int *shift,
>            } else {
>                if (base + p != pfn) {
>                    tmp = (unsigned long)p;
> -                    m = find_first_bit(&tmp, sizeof(tmp));
> +                    m = find_first_bit(&tmp, BITS_PER_LONG);
>                    skip = 1 << m;
>                    mask = skip - 1;
>                    base = pfn;
> -- 
> 2.7.4
> 
> 
> ---
> L'absence de virus dans ce courrier électronique a été vérifiée par le logiciel antivirus Avast.
> https://www.avast.com/antivirus
> 
> --
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Re: [PATCH] IB/mlx5: Fix a parameter of find_first_bit

[Leon Romanovsky]

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On Fri, Aug 26, 2016 at 07:16:17AM +0200, Christophe JAILLET wrote:
> The 2nd parameter of 'find_first_bit' is the number of bits to search.
> In this case, we are passing 'sizeof(tmp)' which is likely to be 4 or 8
> because 'tmp' is an 'unsigned long'.
>
> It is likely that the number of bits of 'tmp' was expected here. So use
> BITS_PER_LONG instead.
>
> It has been spotted by the following coccinelle script:
> @@
> expression ret, x;
>
> @@
> *  ret = \(find_first_bit \| find_first_zero_bit\) (x, sizeof(...));
>
> Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>

Thanks,
Acked-by: Leon Romanovsky <leonro@mellanox.com>

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Re: [PATCH] IB/mlx5: Fix a parameter of find_first_bit

[Doug Ledford]

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On 8/26/2016 1:16 AM, Christophe JAILLET wrote:
> The 2nd parameter of 'find_first_bit' is the number of bits to search.
> In this case, we are passing 'sizeof(tmp)' which is likely to be 4 or 8
> because 'tmp' is an 'unsigned long'.
> 
> It is likely that the number of bits of 'tmp' was expected here. So use
> BITS_PER_LONG instead.

Thanks, applied.


-- 
Doug Ledford <dledford@redhat.com>
    GPG Key ID: 0E572FDD


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