From: Nick Piggin <npiggin@suse.de>
To: Andrew Morton <akpm@osdl.org>, Linus Torvalds <torvalds@osdl.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Linux Memory Management List <linux-mm@kvack.org>
Subject: [patch] buffer: memorder fix
Date: Sat, 20 Jan 2007 08:05:46 +0100 [thread overview]
Message-ID: <20070120070546.GC30774@wotan.suse.de> (raw)
Anyone mind telling me why unlock_buffer, unlike unlock_page, thinks it can
clear the lock without ensuring the critical section is closed (ie. with a
barrier)?
Signed-off-by: Nick Piggin <npiggin@suse.de>
Index: linux-2.6/fs/buffer.c
===================================================================
--- linux-2.6.orig/fs/buffer.c
+++ linux-2.6/fs/buffer.c
@@ -78,6 +78,7 @@ EXPORT_SYMBOL(__lock_buffer);
void fastcall unlock_buffer(struct buffer_head *bh)
{
+ smp_mb__before_clear_bit();
clear_buffer_locked(bh);
smp_mb__after_clear_bit();
wake_up_bit(&bh->b_state, BH_Lock);
--
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reply other threads:[~2007-01-20 7:05 UTC|newest]
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