From: Al Viro <viro@ftp.linux.org.uk>
Date: Sun, 8 Oct 2006 13:32:15 +0000 (+0100)
Subject: [PATCH] sparc32 rwlock fix
X-Git-Tag: v2.6.19-rc2~260
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=7a39f52202a70ff6834e37053e2ee55c7d351621;p=pandora-kernel.git

[PATCH] sparc32 rwlock fix

read_trylock() is broken on sparc32 (doesn't build and didn't work
right, actually).  Proposed fix:

 - make "writer holds lock" distinguishable from "reader tries to grab
   lock"

 - have __raw_read_trylock() try to acquire the mutex (in LSB of lock),
   terminating spin if we see that there's writer holding it.  Then do
   the rest as we do in read_lock().

Thanks to Ingo for discussion...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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