From: Trond Myklebust <trond.myklebust@fys.uio.no>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>,
torvalds@linux-foundation.org, ying.huang@intel.com,
pavel@ucw.cz, nigel@nigel.suspend2.net, rjw@sisk.pl,
vgoyal@redhat.com, mingo@elte.hu, linux-kernel@vger.kernel.org,
kexec@lists.infradead.org
Subject: Re: [PATCH] kexec jump: fix compiling warning on xchg(&kexec_lock, 0) in kernel_kexec()
Date: Wed, 13 Aug 2008 16:15:04 -0400 [thread overview]
Message-ID: <1218658504.9042.61.camel@localhost> (raw)
In-Reply-To: <20080813124406.21091eae.akpm@linux-foundation.org>
On Wed, 2008-08-13 at 12:44 -0700, Andrew Morton wrote:
> - Is xchg() guaranteed to be atomic? That's what atomic_xchg() is for.
Yes, xchg() is guaranteed to be atomic. atomic_xchg() applies only to
the atomic_t type, and is almost always #defined to xchg().
> - xchg() isn't guaranteed to exist on all architectures. atomic_xchg() is.
You appear to be confusing xchg() with cmpxchg(). AFAIK, xchg() exists
on all architectures, and is used in several instances of generic code.
It is particularly extensively used in the networking layer.
Trond
prev parent reply other threads:[~2008-08-13 20:15 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-08-13 9:12 [PATCH] kexec jump: fix compiling warning on xchg(&kexec_lock, 0) in kernel_kexec() Huang Ying
2008-08-13 9:27 ` Andrew Morton
2008-08-13 17:01 ` Linus Torvalds
2008-08-13 17:25 ` Andrew Morton
2008-08-13 17:59 ` Ingo Molnar
2008-08-13 16:57 ` Linus Torvalds
2008-08-13 18:12 ` Eric W. Biederman
2008-08-13 18:31 ` Vivek Goyal
2008-08-13 19:44 ` Andrew Morton
2008-08-13 19:50 ` Linus Torvalds
2008-08-13 20:07 ` Andrew Morton
2008-08-13 20:13 ` Linus Torvalds
2008-08-13 20:25 ` Andrew Morton
2008-08-13 20:31 ` Linus Torvalds
2008-08-13 20:41 ` Andrew Morton
2008-08-13 21:21 ` Vivek Goyal
2008-08-13 22:17 ` Linus Torvalds
2008-08-13 20:15 ` Trond Myklebust [this message]
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