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-Wtautological-constant-compare in drivers/md/dm-raid.c #753

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nathanchance opened this issue Oct 24, 2019 · 3 comments
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-Wtautological-constant-compare in drivers/md/dm-raid.c #753

nathanchance opened this issue Oct 24, 2019 · 3 comments
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@nathanchance
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-Wtautological-compare -Wtautological-constant-compare [BUG] linux A bug that should be fixed in the mainline kernel. [FIXED][LINUX] 5.5 This bug was fixed in Linux 5.5

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@nathanchance
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drivers/md/dm-raid.c:619:8: warning: converting the result of '<<' to a boolean always evaluates to true [-Wtautological-constant-compare]
                r = !RAID10_OFFSET;
                     ^
drivers/md/dm-raid.c:517:28: note: expanded from macro 'RAID10_OFFSET'
#define RAID10_OFFSET                   (1 << 16) /* stripes with data copies area adjacent on devices */
                                           ^
1 warning generated.

Patch submitted: https://lore.kernel.org/lkml/20191024202803.47613-1-natechancellor@gmail.com/
@nathanchance nathanchance added [BUG] linux A bug that should be fixed in the mainline kernel. [PATCH] Submitted A patch has been submitted for review -Wtautological-constant-compare labels Oct 24, 2019
@nathanchance nathanchance self-assigned this Oct 24, 2019
fengguang pushed a commit to 0day-ci/linux that referenced this issue Oct 27, 2019
@nathanchance @intel-lab-lkp
dm raid: Remove unnecessary negation of a shift in raid10_format_to_m…
cc3fb5f 
…d_layout

When building with Clang + -Wtautological-constant-compare:

 drivers/md/dm-raid.c:619:8: warning: converting the result of '<<' to a
 boolean always evaluates to true [-Wtautological-constant-compare]
                 r = !RAID10_OFFSET;
                      ^
 drivers/md/dm-raid.c:517:28: note: expanded from macro 'RAID10_OFFSET'
 #define RAID10_OFFSET                   (1 << 16) /* stripes with data
 copies area adjacent on devices */
                                           ^
 1 warning generated.

Negating a non-zero number will always make it zero, which is the
default value of r in this function so this statement is unnecessary;
remove it so that clang no longer warns.

Link: ClangBuiltLinux#753
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
ruscur pushed a commit to ruscur/linux that referenced this issue Nov 8, 2019
@nathanchance @snitm
dm raid: Remove unnecessary negation of a shift in raid10_format_to_m…
35ad035 
…d_layout

When building with Clang + -Wtautological-constant-compare:

 drivers/md/dm-raid.c:619:8: warning: converting the result of '<<' to a
 boolean always evaluates to true [-Wtautological-constant-compare]
                 r = !RAID10_OFFSET;
                      ^
 drivers/md/dm-raid.c:517:28: note: expanded from macro 'RAID10_OFFSET'
 #define RAID10_OFFSET                   (1 << 16) /* stripes with data
 copies area adjacent on devices */
                                           ^
 1 warning generated.

Negating a non-zero number will always make it zero, which is the
default value of r in this function so this statement is unnecessary;
remove it so that clang no longer warns.

Link: ClangBuiltLinux#753
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
Acked-by: Heinz Mauelshagen <heinzm@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
@nathanchance
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This was apparently picked up...? Never got an email about it and Nick's reviewed-by is missing :/

https://git.kernel.org/next/linux-next/c/35ad035b8398c634d888324a299ec50a84cbc6cc

@nathanchance nathanchance added [PATCH] Accepted A submitted patch has been accepted upstream and removed [PATCH] Submitted A patch has been submitted for review labels Nov 8, 2019
@nickdesaulniers
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YOLO! (I would've gotten away with it too, if it weren't for you god damned kids and your github!)

@nathanchance
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Merged into mainline: https://git.kernel.org/torvalds/c/35ad035b8398c634d888324a299ec50a84cbc6cc

@nathanchance nathanchance added [FIXED][LINUX] 5.5 This bug was fixed in Linux 5.5 and removed [PATCH] Accepted A submitted patch has been accepted upstream labels Nov 25, 2019
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-Wtautological-compare -Wtautological-constant-compare [BUG] linux A bug that should be fixed in the mainline kernel. [FIXED][LINUX] 5.5 This bug was fixed in Linux 5.5
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