From: Peter Zijlstra <peterz@infradead.org>
To: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: linux-kernel@vger.kernel.org, mingo@kernel.org,
jiangshanlai@gmail.com, dipankar@in.ibm.com,
akpm@linux-foundation.org, mathieu.desnoyers@efficios.com,
josh@joshtriplett.org, tglx@linutronix.de, rostedt@goodmis.org,
dhowells@redhat.com, edumazet@google.com, dvhart@linux.intel.com,
fweisbec@gmail.com, oleg@redhat.com, bobby.prani@gmail.com
Subject: Re: [PATCH tip/core/rcu 2/2] documentation: Record reason for rcu_head two-byte alignment
Date: Mon, 22 Aug 2016 18:25:53 +0200 [thread overview]
Message-ID: <20160822162553.GJ10153@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <1471878883-6660-2-git-send-email-paulmck@linux.vnet.ibm.com>
On Mon, Aug 22, 2016 at 08:14:43AM -0700, Paul E. McKenney wrote:
> The __call_rcu() assertion that checks only the bottom bit of the
> rcu_head pointer is a bit counter-intuitive in these days of ubiquitous
> 64-bit systems. This commit therefore records the reason for this
> odd alignment check, namely that m68k guarantees only two-byte alignment
> despite being a 32-bit architectures.
Would not something like:
#ifdef CONFIG_M68K
/*
* m68k is weird and doesn't have naturally aligned types.
*/
WARN_ON_ONCE((unsigned long)head & 1);
#else
WARN_ON_ONCE((unsigned long)head & (sizeof(unsigned long) - 1));
#endif
Be better?
next prev parent reply other threads:[~2016-08-22 16:26 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-08-22 15:14 [PATCH tip/core/rcu 0/2] Documentation updates Paul E. McKenney
2016-08-22 15:14 ` [PATCH tip/core/rcu 1/2] rcutorture: Remove outdated config option description Paul E. McKenney
2016-08-22 15:14 ` [PATCH tip/core/rcu 2/2] documentation: Record reason for rcu_head two-byte alignment Paul E. McKenney
2016-08-22 16:25 ` Peter Zijlstra [this message]
2016-08-22 17:34 ` Paul E. McKenney
2016-08-22 18:48 ` Eric Dumazet
2016-08-22 18:56 ` Peter Zijlstra
2016-08-22 19:18 ` Steven Rostedt
2016-08-22 19:54 ` Paul E. McKenney
2016-08-22 20:48 ` Geert Uytterhoeven
2016-08-22 21:16 ` Paul E. McKenney
2016-08-23 6:39 ` Geert Uytterhoeven
2016-08-23 13:43 ` Paul E. McKenney
2016-08-23 13:45 ` Geert Uytterhoeven
2016-08-23 14:23 ` Paul E. McKenney
2016-08-23 14:30 ` Geert Uytterhoeven
2016-08-23 14:41 ` Paul E. McKenney
2016-08-24 18:03 ` Kirill A. Shutemov
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