From: "Ahmed S. Darwish" <a.darwish@linutronix.de>
To: Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@redhat.com>, Will Deacon <will@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>,
"Paul E. McKenney" <paulmck@kernel.org>,
"Sebastian A. Siewior" <bigeasy@linutronix.de>,
Steven Rostedt <rostedt@goodmis.org>,
LKML <linux-kernel@vger.kernel.org>,
"Ahmed S. Darwish" <a.darwish@linutronix.de>,
Song Liu <song@kernel.org>,
linux-raid@vger.kernel.org
Subject: [PATCH v2 13/18] raid5: Use sequence counter with associated spinlock
Date: Mon, 8 Jun 2020 02:57:24 +0200 [thread overview]
Message-ID: <20200608005729.1874024-14-a.darwish@linutronix.de> (raw)
In-Reply-To: <20200608005729.1874024-1-a.darwish@linutronix.de>
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_spinlock_t data type, which allows to associate a
spinlock with the sequence counter. This enables lockdep to verify that
the 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 <a.darwish@linutronix.de>
---
drivers/md/raid5.c | 2 +-
drivers/md/raid5.h | 2 +-
2 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index ba00e9877f02..69f31c675b58 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -6929,7 +6929,7 @@ static struct r5conf *setup_conf(struct mddev *mddev)
} else
goto abort;
spin_lock_init(&conf->device_lock);
- seqcount_init(&conf->gen_lock);
+ seqcount_spinlock_init(&conf->gen_lock, &conf->device_lock);
mutex_init(&conf->cache_size_mutex);
init_waitqueue_head(&conf->wait_for_quiescent);
init_waitqueue_head(&conf->wait_for_stripe);
diff --git a/drivers/md/raid5.h b/drivers/md/raid5.h
index f90e0704bed9..a2c9e9e9f5ac 100644
--- a/drivers/md/raid5.h
+++ b/drivers/md/raid5.h
@@ -589,7 +589,7 @@ struct r5conf {
int prev_chunk_sectors;
int prev_algo;
short generation; /* increments with every reshape */
- seqcount_t gen_lock; /* lock against generation changes */
+ seqcount_spinlock_t gen_lock; /* lock against generation changes */
unsigned long reshape_checkpoint; /* Time we last updated
* metadata */
long long min_offset_diff; /* minimum difference between
--
2.20.1
next prev parent reply other threads:[~2020-06-08 0:57 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20200519214547.352050-1-a.darwish@linutronix.de>
2020-05-19 21:45 ` [PATCH v1 20/25] raid5: Use sequence counter with associated spinlock Ahmed S. Darwish
[not found] ` <20200608005729.1874024-1-a.darwish@linutronix.de>
2020-06-08 0:57 ` Ahmed S. Darwish [this message]
[not found] ` <20200630054452.3675847-1-a.darwish@linutronix.de>
2020-06-30 5:44 ` [PATCH v3 15/20] " Ahmed S. Darwish
[not found] ` <20200720155530.1173732-1-a.darwish@linutronix.de>
2020-07-20 15:55 ` [PATCH v4 19/24] " Ahmed S. Darwish
2020-07-22 6:40 ` Song Liu
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