[PATCH BUGFIX 0/1] bloc, bfq: fix of a bug introduced by my last patch

[PATCH BUGFIX 0/1] bloc, bfq: fix of a bug introduced by my last patch

[Paolo Valente]

Hi Jens,
unfortunately, the patch of mine that you applied yesterday ("block,
bfq: release oom-queue ref to root group on exit"), does not compile
if CONFIG_BFQ_GROUP_IOSCHED is not defined. I forgot to test that patch
with that option disabled. Honestly, I'm more and more uncertain
about how useful (disabling) that option is ...

In any case, one question about the present patch: I didn't add any
hash for the commit that this patch fixes, because, if I'm not
mistaken, the hash that that commit will have in mainline is not yet
defined. I hope this is the right way to go.

Thanks,
Paolo

Paolo Valente (1):
  block, bfq: compile group put for oom queue only if BFQ_GROUP_IOSCHED
    is set

 block/bfq-iosched.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

--
2.15.1

[PATCH BUGFIX 1/1] block, bfq: compile group put for oom queue only if BFQ_GROUP_IOSCHED is set

[Paolo Valente]

Commit ("block, bfq: release oom-queue ref to root group on exit")
added a missing put of the root bfq group for the oom queue. That put
has to be, and can be, performed only if CONFIG_BFQ_GROUP_IOSCHED is
defined: the function doing the put is even not defined at all if
CONFIG_BFQ_GROUP_IOSCHED is not defined. But that commit makes that
put be invoked regardless of whether CONFIG_BFQ_GROUP_IOSCHED is
defined. This commit fixes this mistake, by making that invocation be
compiled only if CONFIG_BFQ_GROUP_IOSCHED is actually defined.

Fixes ("block, bfq: release oom-queue ref to root group on exit")
Reported-by: Jan Alexander Steffens <jan.steffens@gmail.com>
Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
---
 block/bfq-iosched.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c
index c56a495af2e8..93a97a7fe519 100644
--- a/block/bfq-iosched.c
+++ b/block/bfq-iosched.c
@@ -5015,10 +5015,9 @@ static void bfq_exit_queue(struct elevator_queue *e)
 
 	hrtimer_cancel(&bfqd->idle_slice_timer);
 
+#ifdef CONFIG_BFQ_GROUP_IOSCHED
 	/* release oom-queue reference to root group */
 	bfqg_and_blkg_put(bfqd->root_group);
-
-#ifdef CONFIG_BFQ_GROUP_IOSCHED
 	blkcg_deactivate_policy(bfqd->queue, &blkcg_policy_bfq);
 #else
 	spin_lock_irq(&bfqd->lock);
-- 
2.15.1

Re: [PATCH BUGFIX 1/1] block, bfq: compile group put for oom queue only if BFQ_GROUP_IOSCHED is set

[Jens Axboe]

On 1/10/18 7:58 AM, Paolo Valente wrote:
> Commit ("block, bfq: release oom-queue ref to root group on exit")
> added a missing put of the root bfq group for the oom queue. That put
> has to be, and can be, performed only if CONFIG_BFQ_GROUP_IOSCHED is
> defined: the function doing the put is even not defined at all if
> CONFIG_BFQ_GROUP_IOSCHED is not defined. But that commit makes that
> put be invoked regardless of whether CONFIG_BFQ_GROUP_IOSCHED is
> defined. This commit fixes this mistake, by making that invocation be
> compiled only if CONFIG_BFQ_GROUP_IOSCHED is actually defined.

I already fixed that up yesterday:

http://git.kernel.dk/cgit/linux-block/commit/?h=for-4.16/block&id=8abef10b3de1144cfe968f454946f13eb1ac3d0a

-- 
Jens Axboe