linux-kernel - atafb: fix regression with uninitalized fb_info->mm

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Date:	Tue, 7 Jul 2009 19:15:16 +0200
From:	Krzysztof Helt <krzysztof.h1@...zta.fm>
To:	Linux-fbdev-devel <linux-fbdev-devel@...ts.sourceforge.net>,
	linux-kernel@...r.kernel.org
Cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	akpm@...ux-foundation.org, a.p.zijlstra@...llo.nl, rjw@...k.pl,
	stable@...nel.org, Geert Uytterhoeven <geert@...ux-m68k.org>
Subject: atafb: fix regression with uninitalized fb_info->mm_lock mutex

From: Krzysztof Helt <krzysztof.h1@...pl>

Remove redundant locking of the fb_info->mm_lock mutex before the frambuffer 
is registered.

This fixes a problem with uninitialized the fb_info->mm_lock mutex introduced 
by the commit 537a1bf059f " fbdev: add mutex for fb_mmap locking"

Signed-off-by: Krzysztof Helt <krzysztof.h1@...pl>

---

diff --git a/drivers/video/atafb.c b/drivers/video/atafb.c
index 497ff8a..8cd279b 100644
--- a/drivers/video/atafb.c
+++ b/drivers/video/atafb.c
@@ -2405,6 +2405,9 @@ static int do_fb_set_var(struct fb_var_screeninfo *var, int isactive)
 	return 0;
 }
 
+/* fbhw->encode_fix() must be called with fb_info->mm_lock held
+ * if it is called after the register_framebuffer() - not a case here
+ */
 static int atafb_get_fix(struct fb_fix_screeninfo *fix, struct fb_info *info)
 {
 	struct atafb_par par;
@@ -2414,9 +2417,7 @@ static int atafb_get_fix(struct fb_fix_screeninfo *fix, struct fb_info *info)
 	if (err)
 		return err;
 	memset(fix, 0, sizeof(struct fb_fix_screeninfo));
-	mutex_lock(&info->mm_lock);
 	err = fbhw->encode_fix(fix, &par);
-	mutex_unlock(&info->mm_lock);
 	return err;
 }
 

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