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McKenney" Cc: rcu@vger.kernel.org, linux-kernel@vger.kernel.org, kernel-team@meta.com, rostedt@goodmis.org, Mathieu Desnoyers , Sebastian Andrzej Siewior Subject: Re: [PATCH v3 1/4] srcu: Move rcu_is_watching() checks to srcu_read_{,un}lock_fast() Message-ID: <20250722220446.GA376252@joelbox2> References: <7387f0c2-75bc-420d-aa7e-3a9ac72d369c@paulmck-laptop> <20250721162433.10454-1-paulmck@kernel.org> Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250721162433.10454-1-paulmck@kernel.org> X-ClientProxiedBy: MN2PR05CA0066.namprd05.prod.outlook.com (2603:10b6:208:236::35) To SN7PR12MB8059.namprd12.prod.outlook.com (2603:10b6:806:32b::7) Precedence: bulk X-Mailing-List: rcu@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: SN7PR12MB8059:EE_|DS5PPFA3734E4BA:EE_ X-MS-Office365-Filtering-Correlation-Id: 1d6e1fb6-9730-4d4c-d509-08ddc96bc642 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|366016|376014|1800799024|7053199007; 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McKenney wrote: > The rcu_is_watching() warnings are currently in the SRCU-tree > implementations of __srcu_read_lock_fast() and __srcu_read_unlock_fast(). > However, this makes it difficult to create _notrace variants of > srcu_read_lock_fast() and srcu_read_unlock_fast(). This commit therefore > moves these checks to srcu_read_lock_fast(), srcu_read_unlock_fast(), > srcu_down_read_fast(), and srcu_up_read_fast(). > > Signed-off-by: Paul E. McKenney Reviewed-by: Joel Fernandes thanks, - Joel > Cc: Mathieu Desnoyers > Cc: Steven Rostedt > Cc: Sebastian Andrzej Siewior > --- > include/linux/srcu.h | 4 ++++ > include/linux/srcutree.h | 2 -- > 2 files changed, 4 insertions(+), 2 deletions(-) > > diff --git a/include/linux/srcu.h b/include/linux/srcu.h > index f179700fecafb..478c73d067f7d 100644 > --- a/include/linux/srcu.h > +++ b/include/linux/srcu.h > @@ -275,6 +275,7 @@ static inline struct srcu_ctr __percpu *srcu_read_lock_fast(struct srcu_struct * > { > struct srcu_ctr __percpu *retval; > > + RCU_LOCKDEP_WARN(!rcu_is_watching(), "RCU must be watching srcu_read_lock_fast()."); > srcu_check_read_flavor_force(ssp, SRCU_READ_FLAVOR_FAST); > retval = __srcu_read_lock_fast(ssp); > rcu_try_lock_acquire(&ssp->dep_map); > @@ -295,6 +296,7 @@ static inline struct srcu_ctr __percpu *srcu_read_lock_fast(struct srcu_struct * > static inline struct srcu_ctr __percpu *srcu_down_read_fast(struct srcu_struct *ssp) __acquires(ssp) > { > WARN_ON_ONCE(IS_ENABLED(CONFIG_PROVE_RCU) && in_nmi()); > + RCU_LOCKDEP_WARN(!rcu_is_watching(), "RCU must be watching srcu_down_read_fast()."); > srcu_check_read_flavor_force(ssp, SRCU_READ_FLAVOR_FAST); > return __srcu_read_lock_fast(ssp); > } > @@ -389,6 +391,7 @@ static inline void srcu_read_unlock_fast(struct srcu_struct *ssp, struct srcu_ct > srcu_check_read_flavor(ssp, SRCU_READ_FLAVOR_FAST); > srcu_lock_release(&ssp->dep_map); > __srcu_read_unlock_fast(ssp, scp); > + RCU_LOCKDEP_WARN(!rcu_is_watching(), "RCU must be watching srcu_read_unlock_fast()."); > } > > /** > @@ -405,6 +408,7 @@ static inline void srcu_up_read_fast(struct srcu_struct *ssp, struct srcu_ctr __ > WARN_ON_ONCE(IS_ENABLED(CONFIG_PROVE_RCU) && in_nmi()); > srcu_check_read_flavor(ssp, SRCU_READ_FLAVOR_FAST); > __srcu_read_unlock_fast(ssp, scp); > + RCU_LOCKDEP_WARN(!rcu_is_watching(), "RCU must be watching srcu_up_read_fast()."); > } > > /** > diff --git a/include/linux/srcutree.h b/include/linux/srcutree.h > index bf44d8d1e69ea..043b5a67ef71e 100644 > --- a/include/linux/srcutree.h > +++ b/include/linux/srcutree.h > @@ -244,7 +244,6 @@ static inline struct srcu_ctr __percpu *__srcu_read_lock_fast(struct srcu_struct > { > struct srcu_ctr __percpu *scp = READ_ONCE(ssp->srcu_ctrp); > > - RCU_LOCKDEP_WARN(!rcu_is_watching(), "RCU must be watching srcu_read_lock_fast()."); > if (!IS_ENABLED(CONFIG_NEED_SRCU_NMI_SAFE)) > this_cpu_inc(scp->srcu_locks.counter); /* Y */ > else > @@ -275,7 +274,6 @@ static inline void __srcu_read_unlock_fast(struct srcu_struct *ssp, struct srcu_ > this_cpu_inc(scp->srcu_unlocks.counter); /* Z */ > else > atomic_long_inc(raw_cpu_ptr(&scp->srcu_unlocks)); /* Z */ > - RCU_LOCKDEP_WARN(!rcu_is_watching(), "RCU must be watching srcu_read_unlock_fast()."); > } > > void __srcu_check_read_flavor(struct srcu_struct *ssp, int read_flavor); > -- > 2.40.1 >