Patchwork [U-Boot] UBIFS: Fix dereferencing type-punned pointer compiler warning

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Submitter Dirk Behme
Date Dec. 25, 2010, 9:58 a.m.
Message ID <1293271126-6322-1-git-send-email-dirk.behme@gmail.com>
Download mbox | patch
Permalink /patch/76666/
State Accepted
Commit c7b7d4550d0178dc302c808f974a7beb0f80d3e1
Delegated to: Stefan Roese
Headers show

Comments

Dirk Behme - Dec. 25, 2010, 9:58 a.m.
Fix compiler warning

In file included from ubifs.h:2137:0,
                 from ubifs.c:26:
misc.h: In function 'ubifs_idx_key':
misc.h:263:26: warning: dereferencing type-punned pointer will break strict-aliasing rules

seen with gcc version 4.5.1 (Sourcery G++ Lite 2010.09-50).

No functional change.

CC: Stefan Roese <sr@denx.de>
Signed-off-by: Dirk Behme <dirk.behme@googlemail.com>

---

This was found building 'omap3_pandora' with the above tool chain.

Note: Compiling the ubifs (make fs/ubifs) in a recent mainline kernel
      (2.6.37-rc7) with the same tool chain doesn't give this warning.
      There seems to be no difference in the recent ubifs kernel sources
      regarding this piece of code (structs ubifs_idx_node, ubifs_branch
      and the function ubifs_idx_key in misc.h), though.
      So I'm not sure why this warning is in U-Boot but not in the kernel.
      Different compiler options?

 fs/ubifs/misc.h |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)
Stefan Roese - Jan. 11, 2011, 10:10 a.m.
On Saturday 25 December 2010 10:58:46 Dirk Behme wrote:
> Fix compiler warning
> 
> In file included from ubifs.h:2137:0,
>                  from ubifs.c:26:
> misc.h: In function 'ubifs_idx_key':
> misc.h:263:26: warning: dereferencing type-punned pointer will break
> strict-aliasing rules
> 
> seen with gcc version 4.5.1 (Sourcery G++ Lite 2010.09-50).
> 
> No functional change.

Applied to u-boot-ubi. Thanks.
 
Cheers,
Stefan

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Patch

Index: u-boot.git/fs/ubifs/misc.h
===================================================================
--- u-boot.git.orig/fs/ubifs/misc.h
+++ u-boot.git/fs/ubifs/misc.h
@@ -260,7 +260,8 @@  struct ubifs_branch *ubifs_idx_branch(co
 static inline void *ubifs_idx_key(const struct ubifs_info *c,
 				  const struct ubifs_idx_node *idx)
 {
-	return (void *)((struct ubifs_branch *)idx->branches)->key;
+	const __u8 *branch = idx->branches;
+	return (void *)((struct ubifs_branch *)branch)->key;
 }
 
 /**