A-Team_Digital_Solutions/android_kernel_motorola_sm6375
Watch
2
0
Fork
You've already forked android_kernel_motorola_sm6375
 0
mirror of https://github.com/BobTheBlinker/android_kernel_motorola_sm6375.git synced 2026-10-30 11:41:38 -04:00
Code Issues Projects Releases Packages Wiki Activity

bio: skip atomic inc/dec of ->bi_cnt for most use cases

Browse source 
Struct bio has a reference count that controls when it can be freed.
Most uses cases is allocating the bio, which then returns with a
single reference to it, doing IO, and then dropping that single
reference. We can remove this atomic_dec_and_test() in the completion
path, if nobody else is holding a reference to the bio.

If someone does call bio_get() on the bio, then we flag the bio as
now having valid count and that we must properly honor the reference
count when it's being put.

Tested-by: Robert Elliott <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
This commit is contained in:
Jens Axboe 2015-04-17 16:23:59 -06:00
commit dac56212e8
6 changed files with 30 additions and 12 deletions
Download patch file Download diff file Expand all files Collapse all files

18
block/bio.c
View file

@ -271,7 +271,7 @@ void bio_init(struct bio *bio)
memset(bio, 0, sizeof(*bio));
bio->bi_flags = 1 << BIO_UPTODATE;
atomic_set(&bio->__bi_remaining, 1);
atomic_set(&bio->bi_cnt, 1);
atomic_set(&bio->__bi_cnt, 1);
}
EXPORT_SYMBOL(bio_init);
@ -524,13 +524,17 @@ EXPORT_SYMBOL(zero_fill_bio);
**/
void bio_put(struct bio *bio)
{
BIO_BUG_ON(!atomic_read(&bio->bi_cnt));
/*
* last put frees it
*/
if (atomic_dec_and_test(&bio->bi_cnt))
if (!bio_flagged(bio, BIO_REFFED))
bio_free(bio);
else {
BIO_BUG_ON(!atomic_read(&bio->__bi_cnt));
/*
* last put frees it
*/
if (atomic_dec_and_test(&bio->__bi_cnt))
bio_free(bio);
}
}
EXPORT_SYMBOL(bio_put);