| Message ID | 20240111092722.322454-1-onkarnath.1@samsung.com (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | 1d1726452b3a43f0934edb20aad8941f737aca7a |
| Headers | show |
| Series | [1/1] rcu/sync: remove un-used rcu_sync_enter_start function | expand |
On Thu, Jan 11, 2024 at 02:57:22PM +0530, Onkarnarth wrote: > From: Onkarnath <onkarnath.1@samsung.com> > > With commit '6a010a49b63a ("cgroup: Make !percpu threadgroup_rwsem > operations optional")' usage of rcu_sync_enter_start is removed. > > So this function can also be removed. > > Signed-off-by: Onkarnath <onkarnath.1@samsung.com> > Signed-off-by: Maninder Singh <maninder1.s@samsung.com> Adding Oleg, Peter, and Tejun for their thoughts. Any objections? Thanx, Paul > --- > include/linux/rcu_sync.h | 1 - > kernel/rcu/sync.c | 16 ---------------- > 2 files changed, 17 deletions(-) > > diff --git a/include/linux/rcu_sync.h b/include/linux/rcu_sync.h > index 0027d4c8087c..3860dbb9107a 100644 > --- a/include/linux/rcu_sync.h > +++ b/include/linux/rcu_sync.h > @@ -37,7 +37,6 @@ static inline bool rcu_sync_is_idle(struct rcu_sync *rsp) > } > > extern void rcu_sync_init(struct rcu_sync *); > -extern void rcu_sync_enter_start(struct rcu_sync *); > extern void rcu_sync_enter(struct rcu_sync *); > extern void rcu_sync_exit(struct rcu_sync *); > extern void rcu_sync_dtor(struct rcu_sync *); > diff --git a/kernel/rcu/sync.c b/kernel/rcu/sync.c > index e550f97779b8..86df878a2fee 100644 > --- a/kernel/rcu/sync.c > +++ b/kernel/rcu/sync.c > @@ -24,22 +24,6 @@ void rcu_sync_init(struct rcu_sync *rsp) > init_waitqueue_head(&rsp->gp_wait); > } > > -/** > - * rcu_sync_enter_start - Force readers onto slow path for multiple updates > - * @rsp: Pointer to rcu_sync structure to use for synchronization > - * > - * Must be called after rcu_sync_init() and before first use. > - * > - * Ensures rcu_sync_is_idle() returns false and rcu_sync_{enter,exit}() > - * pairs turn into NO-OPs. > - */ > -void rcu_sync_enter_start(struct rcu_sync *rsp) > -{ > - rsp->gp_count++; > - rsp->gp_state = GP_PASSED; > -} > - > - > static void rcu_sync_func(struct rcu_head *rhp); > > static void rcu_sync_call(struct rcu_sync *rsp) > -- > 2.25.1 >
On 01/16, Paul E. McKenney wrote: > > On Thu, Jan 11, 2024 at 02:57:22PM +0530, Onkarnarth wrote: > > From: Onkarnath <onkarnath.1@samsung.com> > > > > With commit '6a010a49b63a ("cgroup: Make !percpu threadgroup_rwsem > > operations optional")' usage of rcu_sync_enter_start is removed. > > > > So this function can also be removed. > > > > Signed-off-by: Onkarnath <onkarnath.1@samsung.com> > > Signed-off-by: Maninder Singh <maninder1.s@samsung.com> Acked-by: Oleg Nesterov <oleg@redhat.com> For the record, this was already discussed, see https://lore.kernel.org/all/20220725121208.GB28662@redhat.com/ Note also the patch in this message, __rcu_sync_enter(wait => false) is a better alternative if someone needs rcu_sync_enter_start() again. This patch probably makes sense anyway. Not only cgroup_favor_dynmods() can use __rcu_sync_enter(), freeze_super() can use it too to avoid 3 synchronize_rcu()'s in a row. Oleg.
On Tue, Jan 16, 2024 at 08:50:35AM -0800, Paul E. McKenney wrote: > On Thu, Jan 11, 2024 at 02:57:22PM +0530, Onkarnarth wrote: > > From: Onkarnath <onkarnath.1@samsung.com> > > > > With commit '6a010a49b63a ("cgroup: Make !percpu threadgroup_rwsem > > operations optional")' usage of rcu_sync_enter_start is removed. > > > > So this function can also be removed. > > > > Signed-off-by: Onkarnath <onkarnath.1@samsung.com> > > Signed-off-by: Maninder Singh <maninder1.s@samsung.com> > > Adding Oleg, Peter, and Tejun for their thoughts. Any objections? Looks good to me. FWIW, Acked-by: Tejun Heo <tj@kernel.org> Thanks.
On Tue, Jan 16, 2024 at 07:10:59PM +0100, Oleg Nesterov wrote: > On 01/16, Paul E. McKenney wrote: > > > > On Thu, Jan 11, 2024 at 02:57:22PM +0530, Onkarnarth wrote: > > > From: Onkarnath <onkarnath.1@samsung.com> > > > > > > With commit '6a010a49b63a ("cgroup: Make !percpu threadgroup_rwsem > > > operations optional")' usage of rcu_sync_enter_start is removed. > > > > > > So this function can also be removed. > > > > > > Signed-off-by: Onkarnath <onkarnath.1@samsung.com> > > > Signed-off-by: Maninder Singh <maninder1.s@samsung.com> > > Acked-by: Oleg Nesterov <oleg@redhat.com> Queued, thank you all! > For the record, this was already discussed, see > https://lore.kernel.org/all/20220725121208.GB28662@redhat.com/ I am clearly not keeping up. ;-) > Note also the patch in this message, __rcu_sync_enter(wait => false) > is a better alternative if someone needs rcu_sync_enter_start() again. Good to know! I added this to the commit log, so please let me know if this is in any way inappropriate: ------------------------------------------------------------------------ In the words of Oleg Nesterov: __rcu_sync_enter(wait => false) is a better alternative if someone needs rcu_sync_enter_start() again. Link: https://lore.kernel.org/all/20220725121208.GB28662@redhat.com/ ------------------------------------------------------------------------ > This patch probably makes sense anyway. Not only cgroup_favor_dynmods() > can use __rcu_sync_enter(), freeze_super() can use it too to avoid > 3 synchronize_rcu()'s in a row. Thank you for the background information, much appreciated! Thanx, Paul
diff --git a/include/linux/rcu_sync.h b/include/linux/rcu_sync.h index 0027d4c8087c..3860dbb9107a 100644 --- a/include/linux/rcu_sync.h +++ b/include/linux/rcu_sync.h @@ -37,7 +37,6 @@ static inline bool rcu_sync_is_idle(struct rcu_sync *rsp) } extern void rcu_sync_init(struct rcu_sync *); -extern void rcu_sync_enter_start(struct rcu_sync *); extern void rcu_sync_enter(struct rcu_sync *); extern void rcu_sync_exit(struct rcu_sync *); extern void rcu_sync_dtor(struct rcu_sync *); diff --git a/kernel/rcu/sync.c b/kernel/rcu/sync.c index e550f97779b8..86df878a2fee 100644 --- a/kernel/rcu/sync.c +++ b/kernel/rcu/sync.c @@ -24,22 +24,6 @@ void rcu_sync_init(struct rcu_sync *rsp) init_waitqueue_head(&rsp->gp_wait); } -/** - * rcu_sync_enter_start - Force readers onto slow path for multiple updates - * @rsp: Pointer to rcu_sync structure to use for synchronization - * - * Must be called after rcu_sync_init() and before first use. - * - * Ensures rcu_sync_is_idle() returns false and rcu_sync_{enter,exit}() - * pairs turn into NO-OPs. - */ -void rcu_sync_enter_start(struct rcu_sync *rsp) -{ - rsp->gp_count++; - rsp->gp_state = GP_PASSED; -} - - static void rcu_sync_func(struct rcu_head *rhp); static void rcu_sync_call(struct rcu_sync *rsp)