From: Matthew Wilcox <willy@infradead.org>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
linux-kernel@vger.kernel.org,
Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@kernel.org>,
Steven Rostedt <rostedt@goodmis.org>,
Will Deacon <will@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
"Paul E . McKenney" <paulmck@kernel.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
linux-mm@kvack.org
Subject: Re: [PATCH 4/8] mm/swap: Use local_lock for protection
Date: Tue, 19 May 2020 19:17:38 -0700 [thread overview]
Message-ID: <20200520021738.GC16070@bombadil.infradead.org> (raw)
In-Reply-To: <20200519165837.883035d3228c582b9bff1d77@linux-foundation.org>
On Tue, May 19, 2020 at 04:58:37PM -0700, Andrew Morton wrote:
> On Tue, 19 May 2020 22:19:08 +0200 Sebastian Andrzej Siewior <bigeasy@linutronix.de> wrote:
> > + local_lock(swapvec_lock);
>
> It's quite peculiar that these operations appear to be pass-by-value.
> All other locking operations are pass-by-reference - spin_lock(&lock),
> not spin_lock(lock). This is what the eye expects to see and it's
> simply more logical - calling code shouldn't have to "know" that the
> locking operations are implemented as cpp macros. And we'd be in a
> mess if someone tried to convert these to real C functions.
The funny thing is that the documentation gets this right:
+The mapping of local_lock to spinlock_t on PREEMPT_RT kernels has a few
+implications. For example, on a non-PREEMPT_RT kernel the following code
+sequence works as expected::
+
+ local_lock_irq(&local_lock);
+ raw_spin_lock(&lock);
but apparently the implementation changed without the documentation matching.
next prev parent reply other threads:[~2020-05-20 2:17 UTC|newest]
Thread overview: 48+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-19 20:19 [PATCH 0/8] Introduce local_lock() Sebastian Andrzej Siewior
2020-05-19 20:19 ` [PATCH 1/8] locking: " Sebastian Andrzej Siewior
2020-05-20 12:04 ` Peter Zijlstra
2020-05-22 11:05 ` Sebastian Andrzej Siewior
2020-05-22 13:01 ` Peter Zijlstra
2020-05-19 20:19 ` [PATCH 2/8] radix-tree: Use local_lock for protection Sebastian Andrzej Siewior
2020-05-19 20:45 ` Matthew Wilcox
2020-05-19 20:54 ` Steven Rostedt
2020-05-20 2:05 ` Matthew Wilcox
2020-05-20 10:13 ` Sebastian Andrzej Siewior
2020-05-20 10:21 ` Peter Zijlstra
2020-05-20 12:28 ` Thomas Gleixner
2020-05-19 20:19 ` [PATCH 3/8] srcu: Use local_lock() for per-CPU struct srcu_data access Sebastian Andrzej Siewior
2020-05-20 10:24 ` Peter Zijlstra
2020-05-20 12:06 ` Sebastian Andrzej Siewior
2020-05-20 13:27 ` Peter Zijlstra
2020-05-20 17:42 ` Joel Fernandes
2020-05-20 18:28 ` Sebastian Andrzej Siewior
2020-05-20 18:35 ` Peter Zijlstra
2020-05-20 18:44 ` Joel Fernandes
2020-05-20 18:50 ` Uladzislau Rezki
2020-05-20 18:59 ` Joel Fernandes
2020-05-20 18:43 ` Paul E. McKenney
2020-05-22 15:12 ` Sebastian Andrzej Siewior
2020-05-22 17:39 ` Paul E. McKenney
2020-05-23 15:08 ` Sebastian Andrzej Siewior
2020-05-23 16:59 ` Paul E. McKenney
2020-05-24 19:03 ` Sebastian Andrzej Siewior
2020-05-25 3:27 ` Paul E. McKenney
2020-05-26 13:41 ` [PATCH] srcu: Avoid local_irq_save() before acquiring spinlock_t Sebastian Andrzej Siewior
2020-05-26 16:16 ` Paul E. McKenney
2020-05-26 16:31 ` Sebastian Andrzej Siewior
2020-05-19 20:19 ` [PATCH 4/8] mm/swap: Use local_lock for protection Sebastian Andrzej Siewior
2020-05-19 23:58 ` Andrew Morton
2020-05-20 2:17 ` Matthew Wilcox [this message]
2020-05-20 10:53 ` Peter Zijlstra
2020-05-19 20:19 ` [PATCH 5/8] squashfs: make use of local lock in multi_cpu decompressor Sebastian Andrzej Siewior
2020-05-20 10:56 ` Peter Zijlstra
2020-05-19 20:19 ` [PATCH 6/8] connector/cn_proc: Protect send_msg() with a local lock Sebastian Andrzej Siewior
2020-05-20 11:03 ` Peter Zijlstra
2020-05-19 20:19 ` [PATCH 7/8] zram: Use local lock to protect per-CPU data Sebastian Andrzej Siewior
2020-05-20 11:07 ` Peter Zijlstra
2020-05-19 20:19 ` [PATCH 8/8] mm/zswap: " Sebastian Andrzej Siewior
2020-05-19 21:46 ` Song Bao Hua
2020-05-20 10:26 ` Sebastian Andrzej Siewior
2020-05-20 11:13 ` Song Bao Hua
2020-05-20 11:57 ` Sebastian Andrzej Siewior
2020-05-20 12:01 ` Song Bao Hua
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