Messages in this thread | | | Date | Fri, 12 Aug 2022 06:52:02 +0200 | Subject | Re: [PATCH] scsi: target: Save a few cycles in 'transport_lookup_[cmd|tmr]_lun()' | From | Christophe JAILLET <> |
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Le 03/11/2021 à 22:24, Christophe JAILLET a écrit : > Use 'percpu_ref_tryget_live_rcu()' instead of 'percpu_ref_tryget_live()' to > save a few cycles when it is known that the rcu lock is already > taken/released. > > Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr> > --- > drivers/target/target_core_device.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/drivers/target/target_core_device.c b/drivers/target/target_core_device.c > index 44bb380e7390..bfd5d5606522 100644 > --- a/drivers/target/target_core_device.c > +++ b/drivers/target/target_core_device.c > @@ -77,7 +77,7 @@ transport_lookup_cmd_lun(struct se_cmd *se_cmd) > > se_lun = rcu_dereference(deve->se_lun); > > - if (!percpu_ref_tryget_live(&se_lun->lun_ref)) { > + if (!percpu_ref_tryget_live_rcu(&se_lun->lun_ref)) { > se_lun = NULL; > goto out_unlock; > } > @@ -154,7 +154,7 @@ int transport_lookup_tmr_lun(struct se_cmd *se_cmd) > if (deve) { > se_lun = rcu_dereference(deve->se_lun); > > - if (!percpu_ref_tryget_live(&se_lun->lun_ref)) { > + if (!percpu_ref_tryget_live_rcu(&se_lun->lun_ref)) { > se_lun = NULL; > goto out_unlock; > }
Hi, gentle reminder.
Is this patch useful? When I first posted it, percpu_ref_tryget_live_rcu() was really new. Now it is part of linux since 5.16.
Saving a few cycles in a function with "lookup" in its name looks always good to me.
CJ
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