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Message-ID: <alpine.LFD.1.10.0808131247320.3462@nehalem.linux-foundation.org>
Date: Wed, 13 Aug 2008 12:50:57 -0700 (PDT)
From: Linus Torvalds <torvalds@...ux-foundation.org>
To: Andrew Morton <akpm@...ux-foundation.org>
cc: "Eric W. Biederman" <ebiederm@...ssion.com>, ying.huang@...el.com,
pavel@....cz, nigel@...el.suspend2.net, rjw@...k.pl,
vgoyal@...hat.com, mingo@...e.hu, linux-kernel@...r.kernel.org,
kexec@...ts.infradead.org
Subject: Re: [PATCH] kexec jump: fix compiling warning on xchg(&kexec_lock,
0) in kernel_kexec()
On Wed, 13 Aug 2008, Andrew Morton wrote:
> - * in interrupt context :)
> + * Return true if we acquired the lock
> */
> -static int kexec_lock;
> +static inline bool kexec_trylock(void)
> +{
> + return !test_and_set_bit(0, &kexec_bitlock);
Nope. That needs to be an "unsigned long".
But more importantl, why not just make it a lock in the first place?
static DEFINE_SPINLOCK(kexec_lock);
#define kexec_trylock() spin_trylock(&kexec_lock)
#define kexec_unlock() spin_unlock(&kexec_lock)
and then you get it all right and clear and obvious.
Yeah, and I didn't check whether there is anything that is supposed to be
able to sleep. If there is, use a mutex instead of a spinlock, of course.
Linus
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