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SubjectRe: [PATCH] s390/hypfs: Use kmalloc_array() in diag0c_store()
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

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