Patchwork [U-Boot] ext2fs: fix warning: 'blocknxt' may be used uninitialized with gcc 4.2

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Submitter Tom Rini
Date Aug. 7, 2012, 4:58 p.m.
Message ID <1344358714-14032-1-git-send-email-trini@ti.com>
Download mbox | patch
Permalink /patch/175751/
State Accepted
Commit 94c1a20fe78c0d3ba44ee8674b91163dddad0d80
Headers show

Comments

Tom Rini - Aug. 7, 2012, 4:58 p.m.
The above warning was introduced originally in 436da3c "ext2load:
increase read speed" and fixed for newer toolchains in b803273 "ext2fs:
fix warning: 'blocknxt' may be used uninitialized".  This change did not
fix the warning with gcc 4.2, as found in ELDK 4.2.

If we rework the while loop to initalize blocknxt before entering the
warning really goes away.  Tested on am335x with an approx 7mb file and
crc32 in U-Boot befor and after this change.

Cc: Wolfgang Denk <wd@denx.de>
Cc: Eric Nelson <eric.nelson@boundarydevices.com>
Cc: Thierry Reding <thierry.reding@avionic-design.de>
Cc: Jason Cooper <u-boot@lakedaemon.net>
Cc: Andreas Bießmann <andreas.devel@googlemail.com>
Cc: Reinhard Arlt <reinhard.arlt@esd-electronics.com>
Cc: Kim Phillips <kim.phillips@freescale.com>
Signed-off-by: Tom Rini <trini@ti.com>
---
 fs/ext2/ext2fs.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)
Wolfgang Denk - Aug. 7, 2012, 6:55 p.m.
Dear Tom Rini,

In message <1344358714-14032-1-git-send-email-trini@ti.com> you wrote:
> The above warning was introduced originally in 436da3c "ext2load:
> increase read speed" and fixed for newer toolchains in b803273 "ext2fs:
> fix warning: 'blocknxt' may be used uninitialized".  This change did not
> fix the warning with gcc 4.2, as found in ELDK 4.2.
> 
> If we rework the while loop to initalize blocknxt before entering the
> warning really goes away.  Tested on am335x with an approx 7mb file and
> crc32 in U-Boot befor and after this change.
> 
> Cc: Wolfgang Denk <wd@denx.de>
> Cc: Eric Nelson <eric.nelson@boundarydevices.com>
> Cc: Thierry Reding <thierry.reding@avionic-design.de>
> Cc: Jason Cooper <u-boot@lakedaemon.net>
> Cc: Andreas Bießmann <andreas.devel@googlemail.com>
> Cc: Reinhard Arlt <reinhard.arlt@esd-electronics.com>
> Cc: Kim Phillips <kim.phillips@freescale.com>
> Signed-off-by: Tom Rini <trini@ti.com>
> ---
>  fs/ext2/ext2fs.c |    4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)

Applied, thanks.

Best regards,

Wolfgang Denk

Patch

diff --git a/fs/ext2/ext2fs.c b/fs/ext2/ext2fs.c
index 182f0ac..418404e 100644
--- a/fs/ext2/ext2fs.c
+++ b/fs/ext2/ext2fs.c
@@ -440,9 +440,8 @@  int ext2fs_read_file
 		/* grab middle blocks in one go */
 		if (i != pos / blocksize && i < blockcnt - 1 && blockcnt > 3) {
 			int oldblk = blknr;
-			int blocknxt;
+			int blocknxt = ext2fs_read_block(node, i + 1);
 			while (i < blockcnt - 1) {
-				blocknxt = ext2fs_read_block(node, i + 1);
 				if (blocknxt == (oldblk + 1)) {
 					oldblk = blocknxt;
 					i++;
@@ -450,6 +449,7 @@  int ext2fs_read_file
 					blocknxt = ext2fs_read_block(node, i);
 					break;
 				}
+				blocknxt = ext2fs_read_block(node, i);
 			}
 
 			if (oldblk == blknr)