From: Ian Rogers <irogers@google.com>
To: Marco Elver <elver@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>,
Frederic Weisbecker <frederic@kernel.org>,
Ingo Molnar <mingo@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Arnaldo Carvalho de Melo <acme@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
Jiri Olsa <jolsa@redhat.com>, Namhyung Kim <namhyung@kernel.org>,
Dmitry Vyukov <dvyukov@google.com>,
Michael Ellerman <mpe@ellerman.id.au>,
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
Subject: Re: [PATCH v3 10/14] locking/percpu-rwsem: Add percpu_is_write_locked() and percpu_is_read_locked()
Date: Wed, 20 Jul 2022 08:36:18 -0700 [thread overview]
Message-ID: <CAP-5=fX7DoS0eDk=FS14CRjU_UPinH2+0+uD1JPXFMtrb7o1eA@mail.gmail.com> (raw)
In-Reply-To: <20220704150514.48816-11-elver@google.com>
On Mon, Jul 4, 2022 at 8:07 AM Marco Elver <elver@google.com> wrote:
>
> Implement simple accessors to probe percpu-rwsem's locked state:
> percpu_is_write_locked(), percpu_is_read_locked().
>
> Signed-off-by: Marco Elver <elver@google.com>
> Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
Acked-by: Ian Rogers <irogers@google.com>
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
>
next prev parent reply other threads:[~2022-07-20 15:36 UTC|newest]
Thread overview: 49+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-07-04 15:05 [PATCH v3 00/14] perf/hw_breakpoint: Optimize for thousands of tasks Marco Elver
2022-07-04 15:05 ` [PATCH v3 01/14] perf/hw_breakpoint: Add KUnit test for constraints accounting Marco Elver
2022-07-04 15:10 ` Dmitry Vyukov
2022-07-20 15:22 ` Ian Rogers
2022-07-21 16:22 ` Mark Rutland
2022-07-22 9:10 ` Will Deacon
2022-07-22 9:20 ` Dmitry Vyukov
2022-07-22 10:10 ` Will Deacon
2022-07-22 10:31 ` Dmitry Vyukov
2022-07-22 11:03 ` Will Deacon
2022-07-22 13:41 ` Dmitry Vyukov
2022-07-25 11:00 ` Marco Elver
2022-07-04 15:05 ` [PATCH v3 02/14] perf/hw_breakpoint: Provide hw_breakpoint_is_used() and use in test Marco Elver
2022-07-04 15:09 ` Dmitry Vyukov
2022-07-20 15:22 ` Ian Rogers
2022-07-04 15:05 ` [PATCH v3 03/14] perf/hw_breakpoint: Clean up headers Marco Elver
2022-07-20 15:23 ` Ian Rogers
2022-07-04 15:05 ` [PATCH v3 04/14] perf/hw_breakpoint: Optimize list of per-task breakpoints Marco Elver
2022-07-20 15:29 ` Ian Rogers
2022-07-20 15:39 ` Marco Elver
2022-07-04 15:05 ` [PATCH v3 05/14] perf/hw_breakpoint: Mark data __ro_after_init Marco Elver
2022-07-20 15:30 ` Ian Rogers
2022-07-04 15:05 ` [PATCH v3 06/14] perf/hw_breakpoint: Optimize constant number of breakpoint slots Marco Elver
2022-07-20 15:31 ` Ian Rogers
2022-07-04 15:05 ` [PATCH v3 07/14] perf/hw_breakpoint: Make hw_breakpoint_weight() inlinable Marco Elver
2022-07-20 15:32 ` Ian Rogers
2022-07-04 15:05 ` [PATCH v3 08/14] perf/hw_breakpoint: Remove useless code related to flexible breakpoints Marco Elver
2022-07-20 15:34 ` Ian Rogers
2022-07-04 15:05 ` [PATCH v3 09/14] powerpc/hw_breakpoint: Avoid relying on caller synchronization Marco Elver
2022-07-20 15:35 ` Ian Rogers
2022-07-04 15:05 ` [PATCH v3 10/14] locking/percpu-rwsem: Add percpu_is_write_locked() and percpu_is_read_locked() Marco Elver
2022-07-20 15:36 ` Ian Rogers [this message]
2022-08-17 12:47 ` Peter Zijlstra
2022-08-29 6:00 ` Marco Elver
2022-07-04 15:05 ` [PATCH v3 11/14] perf/hw_breakpoint: Reduce contention with large number of tasks Marco Elver
2022-07-20 15:38 ` Ian Rogers
2022-08-17 13:03 ` Peter Zijlstra
2022-08-17 13:14 ` Marco Elver
2022-08-29 8:38 ` Peter Zijlstra
2022-08-29 9:38 ` Marco Elver
2022-07-04 15:05 ` [PATCH v3 12/14] perf/hw_breakpoint: Introduce bp_slots_histogram Marco Elver
2022-07-20 15:40 ` Ian Rogers
2022-07-04 15:05 ` [PATCH v3 13/14] perf/hw_breakpoint: Optimize max_bp_pinned_slots() for CPU-independent task targets Marco Elver
2022-07-20 15:42 ` Ian Rogers
2022-07-04 15:05 ` [PATCH v3 14/14] perf/hw_breakpoint: Optimize toggle_bp_slot() " Marco Elver
2022-07-20 15:44 ` Ian Rogers
2022-07-12 13:39 ` [PATCH v3 00/14] perf/hw_breakpoint: Optimize for thousands of tasks Marco Elver
2022-07-20 15:47 ` Ian Rogers
2022-08-16 14:12 ` Marco Elver
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