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SubjectRe: [PATCH] scsi: virtio_scsi: Remove unnecessary condition checks
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On 10/07/20 08:32, Markus Elfring wrote:
>>>> + mempool_destroy(virtscsi_cmd_pool);
>>>> + virtscsi_cmd_pool = NULL;
>>>> + kmem_cache_destroy(virtscsi_cmd_cache);
>>>> + virtscsi_cmd_cache = NULL;
>>>> return ret;
>>>> }
>>>
>>> How do you think about to add a jump target so that the execution
>>> of a few statements can be avoided according to a previous
>>> null pointer check?
>>
>> The point of the patch is precisely to simplify the code,
>
> I suggest to reconsider also Linux coding style aspects
> for the implementation of the function “init”.
> https://elixir.bootlin.com/linux/v5.8-rc4/source/drivers/scsi/virtio_scsi.c#L980
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/scsi/virtio_scsi.c?id=42f82040ee66db13525dc6f14b8559890b2f4c1c#n980
>
> if (!virtscsi_cmd_cache) {
> pr_err("kmem_cache_create() for virtscsi_cmd_cache failed\n");
> - goto error;
> + return -ENOMEM;
> }

Could be doable, but I don't see a particular benefit. Having a single
error loop is an advantage by itself.

The coding style is a suggestion. Note the difference between

kfree(foo->bar);
kfree(foo);

and

kfree(bar);
kfree(foo);

> See also:
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/process/coding-style.rst?id=42f82040ee66db13525dc6f14b8559890b2f4c1c#n461
>
>
>> executing a couple more instruction is not an issue.
>
> With which update steps would like to achieve such a code variant?
>
> destroy_pool:
> mempool_destroy(virtscsi_cmd_pool);
> virtscsi_cmd_pool = NULL;
> destroy_cache:
> kmem_cache_destroy(virtscsi_cmd_cache);
> virtscsi_cmd_cache = NULL;
> return ret;

... while there's no advantage in this.

Paolo

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