| Message ID | e4a21bc607c39935cb98d4825cd63ba349820550.1635974637.git.christophe.jaillet@wanadoo.fr (mailing list archive) |
|---|---|
| State | Deferred |
| Headers | show |
| Series | scsi: target: Save a few cycles in 'transport_lookup_[cmd|tmr]_lun()' | expand |
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
On 11/3/21 4:24 PM, Christophe JAILLET wrote: > 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; > } The patch looks ok. You just got a little unlucky because the Martin just put some conflicting patches into his 5.20 staging branch: https://git.kernel.org/pub/scm/linux/kernel/git/mkp/scsi.git/log/?h=5.20/scsi-staging so I think you want to build your patch against that tree and branch.
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; }
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(-)