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Darwish" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1593495993; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=UmigHx4BW8UOIynqAPFCArO8Ak7spa6ugzxCvPtvbYY=; b=xxvCKva9RnnBYSKhEn/oFk6GeNyTICD8JlRgqOP9lmH0a3AVC/I061UBqPV6ijq/2TyTQg 5hwnT3OFraM5ZDBhXCak3k5UQv9G7z1xUzrpLmqVx94xL8nCcpFNzvXettOcKy/BZI96pz bPw1VgUB5MdJpEBG7KEsM2dvDat2CE2wkiSmQ0mCih0mEsMQ7FJJxqmvrGfQ+aaHoyzNWP F4woHpUniQT/YG1LuY9E9XpKM4vhUiKq7zrqadY9u/lQo1vVvK8vzwOPBmGjJN2nK5dE+t yqWcqiNltd8GDcukDboajYzofWHgCk/H2TlRATT90kzxLRS1XLT0tJ0ePgTriw== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1593495993; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=UmigHx4BW8UOIynqAPFCArO8Ak7spa6ugzxCvPtvbYY=; b=Dr+zoPA+8MQv7+LzU7NqEM6ykc3bBaGhRPqfTb57yMiC9ZgBc8aN+k7DvAMaAeNN55QU+g q6pEtb/sma+PW0Cw== To: Peter Zijlstra , Ingo Molnar , Will Deacon Cc: Thomas Gleixner , "Paul E. McKenney" , "Sebastian A. Siewior" , Steven Rostedt , LKML , "Ahmed S. Darwish" Subject: [PATCH v3 20/20] hrtimer: Use sequence counter with associated raw spinlock Date: Tue, 30 Jun 2020 07:44:52 +0200 Message-Id: <20200630054452.3675847-21-a.darwish@linutronix.de> In-Reply-To: <20200630054452.3675847-1-a.darwish@linutronix.de> References: <20200519214547.352050-1-a.darwish@linutronix.de> <20200630054452.3675847-1-a.darwish@linutronix.de> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org A sequence counter write side critical section must be protected by some form of locking to serialize writers. A plain seqcount_t does not contain the information of which lock must be held when entering a write side critical section. Use the new seqcount_raw_spinlock_t data type, which allows to associate a raw spinlock with the sequence counter. This enables lockdep to verify that the raw spinlock used for writer serialization is held when the write side critical section is entered. If lockdep is disabled this lock association is compiled out and has neither storage size nor runtime overhead. Signed-off-by: Ahmed S. Darwish --- include/linux/hrtimer.h | 2 +- kernel/time/hrtimer.c | 13 ++++++++++--- 2 files changed, 11 insertions(+), 4 deletions(-) diff --git a/include/linux/hrtimer.h b/include/linux/hrtimer.h index 15c8ac313678..25993b86ac5c 100644 --- a/include/linux/hrtimer.h +++ b/include/linux/hrtimer.h @@ -159,7 +159,7 @@ struct hrtimer_clock_base { struct hrtimer_cpu_base *cpu_base; unsigned int index; clockid_t clockid; - seqcount_t seq; + seqcount_raw_spinlock_t seq; struct hrtimer *running; struct timerqueue_head active; ktime_t (*get_time)(void); diff --git a/kernel/time/hrtimer.c b/kernel/time/hrtimer.c index d89da1c7e005..c4038511d5c9 100644 --- a/kernel/time/hrtimer.c +++ b/kernel/time/hrtimer.c @@ -135,7 +135,11 @@ static const int hrtimer_clock_to_base_table[MAX_CLOCKS] = { * timer->base->cpu_base */ static struct hrtimer_cpu_base migration_cpu_base = { - .clock_base = { { .cpu_base = &migration_cpu_base, }, }, + .clock_base = { { + .cpu_base = &migration_cpu_base, + .seq = SEQCNT_RAW_SPINLOCK_ZERO(migration_cpu_base.seq, + &migration_cpu_base.lock), + }, }, }; #define migration_base migration_cpu_base.clock_base[0] @@ -1998,8 +2002,11 @@ int hrtimers_prepare_cpu(unsigned int cpu) int i; for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++) { - cpu_base->clock_base[i].cpu_base = cpu_base; - timerqueue_init_head(&cpu_base->clock_base[i].active); + struct hrtimer_clock_base *clock_b = &cpu_base->clock_base[i]; + + clock_b->cpu_base = cpu_base; + seqcount_raw_spinlock_init(&clock_b->seq, &cpu_base->lock); + timerqueue_init_head(&clock_b->active); } cpu_base->cpu = cpu; -- 2.20.1