Messages in this thread | | | Subject | Re: [PATCH 1/5] ISDN-Gigaset: Use kmalloc_array() in two functions | From | SF Markus Elfring <> | Date | Wed, 28 Sep 2016 18:38:10 +0200 |
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>> * Multiplications for the size determination of memory allocations >> indicated that array data structures should be processed. >> Thus use the corresponding function "kmalloc_array". > > Was the current code incorrect?
I suggest to use a safer interface for array allocations.
> What makes kmalloc_array() better?
1. How do you think about the safety checks that this function provides?
2. Will you be also affected by further software evolution here? 2016-07-26 mm: faster kmalloc_array(), kcalloc() https://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git/commit/?id=91c6a05f72a996bee5133e76374ab3ad7d3b9b72
> I'm not going to change code just because some checker suggests to do so.
The script "checkpatch.pl" can point information out like the following.
WARNING: Prefer kmalloc_array over kmalloc with multiply
>> This issue was detected by using the Coccinelle software. > > So? And which coccinelle script was actually used?
How do you think about to look into related information sources? https://github.com/coccinelle/coccinelle/issues/81
Would you like to experiment any further with an excerpt?
@replacement1@ expression count, target; type T; @@ target = - kmalloc(sizeof(T) * (count) + kmalloc_array(count, sizeof(T) , ...);
@replacement2@ expression count, pointer, target; @@ target = - kmalloc(sizeof(*pointer) * (count) + kmalloc_array(count, sizeof(*pointer) , ...);
> I couldn't spot a coccinelle script doing that in the current tree.
This is true for such a software update opportunity.
>> * Replace the specification of a data structure by a pointer dereference >> to make the corresponding size determination a bit safer according to >> the Linux coding style convention. > > I'm not happy with you mixing this with the above, less trivial, change.
I find that it is a useful combination. - A parameter is adjusted together with a special function name.
>> - drv->cs = kmalloc(minors * sizeof *drv->cs, GFP_KERNEL); >> + drv->cs = kmalloc_array(minors, sizeof(*drv->cs), GFP_KERNEL); > > For "minors" the same holds as for "channels", above. > > And you snuck in a parentheses change. That should have probably been > merged with 5/5.
Would you prefer to add them in another update step?
Regards, Markus
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