After checking all possible call chains to kmalloc here,
my tool finds that kmalloc is never called in atomic context.
Thus GFP_ATOMIC is not necessary, and it can be replaced with GFP_KERNEL.
This is found by a static analysis tool named DCNS written by myself.
Signed-off-by: Jia-Ju Bai <[email protected]>
---
block/blk-tag.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/block/blk-tag.c b/block/blk-tag.c
index 09f19c6..84db7f663 100644
--- a/block/blk-tag.c
+++ b/block/blk-tag.c
@@ -124,7 +124,7 @@ static struct blk_queue_tag *__blk_queue_init_tags(struct request_queue *q,
{
struct blk_queue_tag *tags;
- tags = kmalloc(sizeof(struct blk_queue_tag), GFP_ATOMIC);
+ tags = kmalloc(sizeof(struct blk_queue_tag), GFP_KERNEL);
if (!tags)
goto fail;
--
1.7.9.5
On 1/24/18 8:38 PM, Jia-Ju Bai wrote:
> After checking all possible call chains to kmalloc here,
> my tool finds that kmalloc is never called in atomic context.
> Thus GFP_ATOMIC is not necessary, and it can be replaced with GFP_KERNEL.
>
> This is found by a static analysis tool named DCNS written by myself.
These two look OK to me, mostly. One issue is that blk_queue_init_tags()
can be used to resize tags, in which case it's called with the
queue lock held. Nobody is using it like that anymore, though. So I'd
prefer if you did a v2 of this patch, and include a correction to that
comment.
--
Jens Axboe
On 2018/1/25 11:44, Jens Axboe wrote:
> On 1/24/18 8:38 PM, Jia-Ju Bai wrote:
>> After checking all possible call chains to kmalloc here,
>> my tool finds that kmalloc is never called in atomic context.
>> Thus GFP_ATOMIC is not necessary, and it can be replaced with GFP_KERNEL.
>>
>> This is found by a static analysis tool named DCNS written by myself.
> These two look OK to me, mostly.
It sounds good :)
> One issue is that blk_queue_init_tags()
> can be used to resize tags, in which case it's called with the
> queue lock held. Nobody is using it like that anymore, though. So I'd
> prefer if you did a v2 of this patch, and include a correction to that
> comment.
>
I am not sure what you mean...
Do you mean that the code in blk_queue_init_tags:
else if (q->queue_tags) {
...
}
can be deleted?
Or just delete the comment before blk_queue_init_tags?
* Queue lock must be held here if the function is called to resize an
* existing map.
**/
Or add the description "The case that queue lock held is never used" in
my patches?
Thanks,
Jia-Ju Bai