Re: [PATCH] VFS: br_write_lock locks on possible CPUs other thanonline CPUs

From: Andrew Morton
Date: Wed Dec 21 2011 - 17:12:33 EST


On Thu, 22 Dec 2011 02:45:29 +0530
"Srivatsa S. Bhat" <srivatsa.bhat@xxxxxxxxxxxxxxxxxx> wrote:

off-topic, but the lockdep stuff in include/linux/lglock.h
(LOCKDEP_INIT_MAP and DEFINE_LGLOCK_LOCKDEP) appears to be dead code.

> --- a/include/linux/lglock.h
> +++ b/include/linux/lglock.h
> @@ -22,6 +22,7 @@
> #include <linux/spinlock.h>
> #include <linux/lockdep.h>
> #include <linux/percpu.h>
> +#include <linux/cpu.h>
>
> /* can make br locks by using local lock for read side, global lock for write */
> #define br_lock_init(name) name##_lock_init()
> @@ -72,9 +73,31 @@
>
> #define DEFINE_LGLOCK(name) \
> \
> + DEFINE_SPINLOCK(name##_cpu_lock); \
> + cpumask_t name##_cpus __read_mostly; \
> DEFINE_PER_CPU(arch_spinlock_t, name##_lock); \
> DEFINE_LGLOCK_LOCKDEP(name); \
> \

also off-topic: we can't define a static lglock with this macro.
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