From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Bart Van Assche To: "axboe@kernel.dk" CC: "linux-block@vger.kernel.org" , "shli@fb.com" Subject: Re: [PATCH] blk-throttle: Suppress a compiler warning Date: Thu, 20 Apr 2017 15:36:27 +0000 Message-ID: <1492702586.2642.5.camel@sandisk.com> References: <20170419235504.5463-1-bart.vanassche@sandisk.com> <089b9e20-c20d-1d10-f230-4aebbb5f03ee@kernel.dk> In-Reply-To: <089b9e20-c20d-1d10-f230-4aebbb5f03ee@kernel.dk> Content-Type: text/plain; charset="windows-1251" MIME-Version: 1.0 List-ID: On Wed, 2017-04-19 at 18:09 -0600, Jens Axboe wrote: > On 04/19/2017 05:55 PM, Bart Van Assche wrote: > > Avoid that the following warning is reported when building with > > W=3D1 and with CONFIG_BLK_DEV_THROTTLING_LOW=3Dn: > >=20 > > block/blk-throttle.c: In function =91blk_throtl_bio=92: > > block/blk-throttle.c:2042:6: warning: variable =91ret=92 set but not us= ed [-Wunused-but-set-variable] > > int ret; > > ^~~ > >=20 > > Signed-off-by: Bart Van Assche > > Cc: Shaohua Li > > --- > > block/blk-throttle.c | 4 ++++ > > 1 file changed, 4 insertions(+) > >=20 > > diff --git a/block/blk-throttle.c b/block/blk-throttle.c > > index c82bf9b1fe72..9081ed9a5345 100644 > > --- a/block/blk-throttle.c > > +++ b/block/blk-throttle.c > > @@ -2059,6 +2059,10 @@ bool blk_throtl_bio(struct request_queue *q, str= uct blkcg_gq *blkg, > > if (ret =3D=3D 0 || ret =3D=3D -EBUSY) > > bio->bi_cg_private =3D tg; > > blk_stat_set_issue(&bio->bi_issue_stat, bio_sectors(bio)); > > +#else > > + /* Avoid that the compiler complains about not using ret */ > > + if (ret) { > > + } > > #endif >=20 > Ugh, that may get rid of the warning, but it does not help on > the readability or the ifdefs. How about something like the below? > Naming could probably be improved... >=20 >=20 > diff --git a/block/blk-throttle.c b/block/blk-throttle.c > index c82bf9b1fe72..b78db2e5fdff 100644 > --- a/block/blk-throttle.c > +++ b/block/blk-throttle.c > @@ -2030,6 +2030,20 @@ static inline void throtl_update_latency_buckets(s= truct throtl_data *td) > } > #endif > =20 > +static void blk_throtl_assoc_bio(struct throtl_grp *tg, struct bio *bio) > +{ > +#ifdef CONFIG_BLK_DEV_THROTTLING_LOW > + int ret; > + > + ret =3D bio_associate_current(bio); > + if (ret =3D=3D 0 || ret =3D=3D -EBUSY) > + bio->bi_cg_private =3D tg; > + blk_stat_set_issue(&bio->bi_issue_stat, bio_sectors(bio)); > +#else > + bio_associate_current(bio); > +#endif > +} > + > bool blk_throtl_bio(struct request_queue *q, struct blkcg_gq *blkg, > struct bio *bio) > { > @@ -2039,7 +2053,6 @@ bool blk_throtl_bio(struct request_queue *q, struct= blkcg_gq *blkg, > bool rw =3D bio_data_dir(bio); > bool throttled =3D false; > struct throtl_data *td =3D tg->td; > - int ret; > =20 > WARN_ON_ONCE(!rcu_read_lock_held()); > =20 > @@ -2054,12 +2067,7 @@ bool blk_throtl_bio(struct request_queue *q, struc= t blkcg_gq *blkg, > if (unlikely(blk_queue_bypass(q))) > goto out_unlock; > =20 > - ret =3D bio_associate_current(bio); > -#ifdef CONFIG_BLK_DEV_THROTTLING_LOW > - if (ret =3D=3D 0 || ret =3D=3D -EBUSY) > - bio->bi_cg_private =3D tg; > - blk_stat_set_issue(&bio->bi_issue_stat, bio_sectors(bio)); > -#endif > + blk_throtl_assoc_bio(tg, bio); > blk_throtl_update_idletime(tg); > =20 > sq =3D &tg->service_queue; >=20 Hello Jens, The above patch looks fine to me. Do you want to queue this patch with my Reviewed-by or do you prefer that I post the above as a v2? Thanks, Bart.=