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Wed, 20 Jul 2022 08:36:31 -0700 (PDT) MIME-Version: 1.0 References: <20220704150514.48816-1-elver@google.com> <20220704150514.48816-11-elver@google.com> In-Reply-To: <20220704150514.48816-11-elver@google.com> From: Ian Rogers Date: Wed, 20 Jul 2022 08:36:18 -0700 Message-ID: Subject: Re: [PATCH v3 10/14] locking/percpu-rwsem: Add percpu_is_write_locked() and percpu_is_read_locked() To: Marco Elver Cc: Peter Zijlstra , Frederic Weisbecker , Ingo Molnar , Thomas Gleixner , Arnaldo Carvalho de Melo , Mark Rutland , Alexander Shishkin , Jiri Olsa , Namhyung Kim , Dmitry Vyukov , Michael Ellerman , linuxppc-dev@lists.ozlabs.org, linux-perf-users@vger.kernel.org, x86@kernel.org, linux-sh@vger.kernel.org, kasan-dev@googlegroups.com, linux-kernel@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jul 4, 2022 at 8:07 AM Marco Elver wrote: > > Implement simple accessors to probe percpu-rwsem's locked state: > percpu_is_write_locked(), percpu_is_read_locked(). > > Signed-off-by: Marco Elver > Reviewed-by: Dmitry Vyukov Acked-by: Ian Rogers Thanks, Ian > --- > v2: > * New patch. > --- > include/linux/percpu-rwsem.h | 6 ++++++ > kernel/locking/percpu-rwsem.c | 6 ++++++ > 2 files changed, 12 insertions(+) > > diff --git a/include/linux/percpu-rwsem.h b/include/linux/percpu-rwsem.h > index 5fda40f97fe9..36b942b67b7d 100644 > --- a/include/linux/percpu-rwsem.h > +++ b/include/linux/percpu-rwsem.h > @@ -121,9 +121,15 @@ static inline void percpu_up_read(struct percpu_rw_semaphore *sem) > preempt_enable(); > } > > +extern bool percpu_is_read_locked(struct percpu_rw_semaphore *); > extern void percpu_down_write(struct percpu_rw_semaphore *); > extern void percpu_up_write(struct percpu_rw_semaphore *); > > +static inline bool percpu_is_write_locked(struct percpu_rw_semaphore *sem) > +{ > + return atomic_read(&sem->block); > +} > + > extern int __percpu_init_rwsem(struct percpu_rw_semaphore *, > const char *, struct lock_class_key *); > > diff --git a/kernel/locking/percpu-rwsem.c b/kernel/locking/percpu-rwsem.c > index 5fe4c5495ba3..213d114fb025 100644 > --- a/kernel/locking/percpu-rwsem.c > +++ b/kernel/locking/percpu-rwsem.c > @@ -192,6 +192,12 @@ EXPORT_SYMBOL_GPL(__percpu_down_read); > __sum; \ > }) > > +bool percpu_is_read_locked(struct percpu_rw_semaphore *sem) > +{ > + return per_cpu_sum(*sem->read_count) != 0; > +} > +EXPORT_SYMBOL_GPL(percpu_is_read_locked); > + > /* > * Return true if the modular sum of the sem->read_count per-CPU variable is > * zero. If this sum is zero, then it is stable due to the fact that if any > -- > 2.37.0.rc0.161.g10f37bed90-goog >