* [PATCH] s390/hypfs: Use kmalloc_array() in diag0c_store()
@ 2016-09-01 9:38 SF Markus Elfring
2016-09-01 10:32 ` Heiko Carstens
0 siblings, 1 reply; 4+ messages in thread
From: SF Markus Elfring @ 2016-09-01 9:38 UTC (permalink / raw)
To: linux-s390, Heiko Carstens, Martin Schwidefsky, Michael Holzheu
Cc: LKML, kernel-janitors, Julia Lawall, Paolo Bonzini
From: Markus Elfring <elfring@users.sourceforge.net>
Date: Thu, 1 Sep 2016 11:30:58 +0200
A multiplication for the size determination of a memory allocation
indicated that an array data structure should be processed.
Thus use the corresponding function "kmalloc_array".
This issue was detected by using the Coccinelle software.
Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
---
arch/s390/hypfs/hypfs_diag0c.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/arch/s390/hypfs/hypfs_diag0c.c b/arch/s390/hypfs/hypfs_diag0c.c
index 0f1927c..61418a8 100644
--- a/arch/s390/hypfs/hypfs_diag0c.c
+++ b/arch/s390/hypfs/hypfs_diag0c.c
@@ -48,7 +48,9 @@ static void *diag0c_store(unsigned int *count)
get_online_cpus();
cpu_count = num_online_cpus();
- cpu_vec = kmalloc(sizeof(*cpu_vec) * num_possible_cpus(), GFP_KERNEL);
+ cpu_vec = kmalloc_array(num_possible_cpus(),
+ sizeof(*cpu_vec),
+ GFP_KERNEL);
if (!cpu_vec)
goto fail_put_online_cpus;
/* Note: Diag 0c needs 8 byte alignment and real storage */
--
2.9.3
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH] s390/hypfs: Use kmalloc_array() in diag0c_store()
2016-09-01 9:38 [PATCH] s390/hypfs: Use kmalloc_array() in diag0c_store() SF Markus Elfring
@ 2016-09-01 10:32 ` Heiko Carstens
2016-09-01 15:39 ` Paolo Bonzini
0 siblings, 1 reply; 4+ messages in thread
From: Heiko Carstens @ 2016-09-01 10:32 UTC (permalink / raw)
To: SF Markus Elfring
Cc: linux-s390, Martin Schwidefsky, Michael Holzheu, LKML,
kernel-janitors, Julia Lawall, Paolo Bonzini
On Thu, Sep 01, 2016 at 11:38:15AM +0200, SF Markus Elfring wrote:
> From: Markus Elfring <elfring@users.sourceforge.net>
> Date: Thu, 1 Sep 2016 11:30:58 +0200
>
> A multiplication for the size determination of a memory allocation
> indicated that an array data structure should be processed.
> Thus use the corresponding function "kmalloc_array".
>
> This issue was detected by using the Coccinelle software.
>
> Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
> ---
> arch/s390/hypfs/hypfs_diag0c.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/arch/s390/hypfs/hypfs_diag0c.c b/arch/s390/hypfs/hypfs_diag0c.c
> index 0f1927c..61418a8 100644
> --- a/arch/s390/hypfs/hypfs_diag0c.c
> +++ b/arch/s390/hypfs/hypfs_diag0c.c
> @@ -48,7 +48,9 @@ static void *diag0c_store(unsigned int *count)
>
> get_online_cpus();
> cpu_count = num_online_cpus();
> - cpu_vec = kmalloc(sizeof(*cpu_vec) * num_possible_cpus(), GFP_KERNEL);
> + cpu_vec = kmalloc_array(num_possible_cpus(),
> + sizeof(*cpu_vec),
> + GFP_KERNEL);
How does this improve the situation? For any real life scenario this can't
overflow, but it does add an extra (pointless) runtime check, since
num_possible_cpus() is not a compile time constant.
So, why is this an "issue"?
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] s390/hypfs: Use kmalloc_array() in diag0c_store()
2016-09-01 10:32 ` Heiko Carstens
@ 2016-09-01 15:39 ` Paolo Bonzini
2016-09-01 16:53 ` Michael Holzheu
0 siblings, 1 reply; 4+ messages in thread
From: Paolo Bonzini @ 2016-09-01 15:39 UTC (permalink / raw)
To: Heiko Carstens, SF Markus Elfring
Cc: linux-s390, Martin Schwidefsky, Michael Holzheu, LKML,
kernel-janitors, Julia Lawall
On 01/09/2016 12:32, Heiko Carstens wrote:
> On Thu, Sep 01, 2016 at 11:38:15AM +0200, SF Markus Elfring wrote:
>> From: Markus Elfring <elfring@users.sourceforge.net>
>> Date: Thu, 1 Sep 2016 11:30:58 +0200
>>
>> A multiplication for the size determination of a memory allocation
>> indicated that an array data structure should be processed.
>> Thus use the corresponding function "kmalloc_array".
>>
>> This issue was detected by using the Coccinelle software.
>>
>> Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
>> ---
>> arch/s390/hypfs/hypfs_diag0c.c | 4 +++-
>> 1 file changed, 3 insertions(+), 1 deletion(-)
>>
>> diff --git a/arch/s390/hypfs/hypfs_diag0c.c b/arch/s390/hypfs/hypfs_diag0c.c
>> index 0f1927c..61418a8 100644
>> --- a/arch/s390/hypfs/hypfs_diag0c.c
>> +++ b/arch/s390/hypfs/hypfs_diag0c.c
>> @@ -48,7 +48,9 @@ static void *diag0c_store(unsigned int *count)
>>
>> get_online_cpus();
>> cpu_count = num_online_cpus();
>> - cpu_vec = kmalloc(sizeof(*cpu_vec) * num_possible_cpus(), GFP_KERNEL);
>> + cpu_vec = kmalloc_array(num_possible_cpus(),
>> + sizeof(*cpu_vec),
>> + GFP_KERNEL);
>
> How does this improve the situation? For any real life scenario this can't
> overflow, but it does add an extra (pointless) runtime check, since
> num_possible_cpus() is not a compile time constant.
>
> So, why is this an "issue"?
It's not an issue but I for one still prefer consistent use of
kmalloc_array and kcalloc.
Paolo
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] s390/hypfs: Use kmalloc_array() in diag0c_store()
2016-09-01 15:39 ` Paolo Bonzini
@ 2016-09-01 16:53 ` Michael Holzheu
0 siblings, 0 replies; 4+ messages in thread
From: Michael Holzheu @ 2016-09-01 16:53 UTC (permalink / raw)
To: Paolo Bonzini
Cc: Heiko Carstens, SF Markus Elfring, linux-s390, Martin Schwidefsky,
LKML, kernel-janitors, Julia Lawall
Am Thu, 1 Sep 2016 17:39:02 +0200
schrieb Paolo Bonzini <pbonzini@redhat.com>:
>
>
> On 01/09/2016 12:32, Heiko Carstens wrote:
> > On Thu, Sep 01, 2016 at 11:38:15AM +0200, SF Markus Elfring wrote:
> >> From: Markus Elfring <elfring@users.sourceforge.net>
> >> Date: Thu, 1 Sep 2016 11:30:58 +0200
> >>
> >> A multiplication for the size determination of a memory allocation
> >> indicated that an array data structure should be processed.
> >> Thus use the corresponding function "kmalloc_array".
> >>
> >> This issue was detected by using the Coccinelle software.
> >>
> >> Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
> >> ---
> >> arch/s390/hypfs/hypfs_diag0c.c | 4 +++-
> >> 1 file changed, 3 insertions(+), 1 deletion(-)
> >>
> >> diff --git a/arch/s390/hypfs/hypfs_diag0c.c
> >> b/arch/s390/hypfs/hypfs_diag0c.c index 0f1927c..61418a8 100644
> >> --- a/arch/s390/hypfs/hypfs_diag0c.c
> >> +++ b/arch/s390/hypfs/hypfs_diag0c.c
> >> @@ -48,7 +48,9 @@ static void *diag0c_store(unsigned int *count)
> >>
> >> get_online_cpus();
> >> cpu_count = num_online_cpus();
> >> - cpu_vec = kmalloc(sizeof(*cpu_vec) * num_possible_cpus(),
> >> GFP_KERNEL);
> >> + cpu_vec = kmalloc_array(num_possible_cpus(),
> >> + sizeof(*cpu_vec),
> >> + GFP_KERNEL);
> >
> > How does this improve the situation? For any real life scenario
> > this can't overflow, but it does add an extra (pointless) runtime
> > check, since num_possible_cpus() is not a compile time constant.
> >
> > So, why is this an "issue"?
>
> It's not an issue but I for one still prefer consistent use of
> kmalloc_array and kcalloc.
Hello Paolo,
I will keep this in mind for future code, but would prefer not changing
this now.
Michael
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2016-09-01 21:30 UTC | newest]
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2016-09-01 9:38 [PATCH] s390/hypfs: Use kmalloc_array() in diag0c_store() SF Markus Elfring
2016-09-01 10:32 ` Heiko Carstens
2016-09-01 15:39 ` Paolo Bonzini
2016-09-01 16:53 ` Michael Holzheu
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