Messages in this thread Patch in this message |  | | Subject | Re: [PATCH] fs/btrfs: Fix uninitialized variable | From | Christophe JAILLET <> | Date | Sun, 2 May 2021 12:17:51 +0200 |
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Le 02/05/2021 à 00:50, Khaled ROMDHANI a écrit : > Fix the warning: variable 'zone' is used > uninitialized whenever '?:' condition is true. > > Fix that by preventing the code to reach > the last assertion. If the variable 'mirror' > is invalid, the assertion fails and we return > immediately. > > Reported-by: kernel test robot <lkp@intel.com> > Signed-off-by: Khaled ROMDHANI <khaledromdhani216@gmail.com> > --- > fs/btrfs/zoned.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/fs/btrfs/zoned.c b/fs/btrfs/zoned.c > index 8250ab3f0868..23da9d8dc184 100644 > --- a/fs/btrfs/zoned.c > +++ b/fs/btrfs/zoned.c > @@ -145,7 +145,7 @@ static inline u32 sb_zone_number(int shift, int mirror) > case 2: zone = 1ULL << (BTRFS_SB_LOG_SECOND_SHIFT - shift); break; > default: > ASSERT((u32)mirror < 3); > - break; > + return 0; > } > > ASSERT(zone <= U32_MAX); > > base-commit: b5c294aac8a6164ddf38bfbdd1776091b4a1eeba > Hi,
just a few comments.
If I understand correctly, what you try to do is to silence a compiler warning if no case branch is taken.
First, all your proposals are based on the previous one. I find it hard to follow because we don't easily see what are the differences since the beginning.
The "base-commit" at the bottom of your mail, is related to your own local tree, I guess. It can't be used by any-one.
My understanding it that a patch, should it be v2, v3..., must apply to the current tree. (In my case, it is the latest linux-next) This is not the case here and you have to apply each step to see the final result.
Should this version be fine, a maintainer wouldn't be able to apply it as-is.
You also try to take into account previous comments to check for incorrect negative values for minor and catch (the can't happen today) cases, should BTRFS_SUPER_MIRROR_MAX change and this function remain the same.
So, why hard-coding '3'? The reason of magic numbers are hard to remember. You should avoid them or add a comment about it.
My own personal variation would be something like the code below (untested).
Hope this helps.
CJ
diff --git a/fs/btrfs/zoned.c b/fs/btrfs/zoned.c index 70b23a0d03b1..75fe5f001d8b 100644 --- a/fs/btrfs/zoned.c +++ b/fs/btrfs/zoned.c @@ -138,11 +138,14 @@ static inline u32 sb_zone_number(int shift, int mirror) { u64 zone;
- ASSERT(mirror < BTRFS_SUPER_MIRROR_MAX); + ASSERT(mirror >= 0 && mirror < BTRFS_SUPER_MIRROR_MAX); switch (mirror) { case 0: zone = 0; break; case 1: zone = 1ULL << (BTRFS_SB_LOG_FIRST_SHIFT - shift); break; case 2: zone = 1ULL << (BTRFS_SB_LOG_SECOND_SHIFT - shift); break; + default: + ASSERT(! "mirror < BTRFS_SUPER_MIRROR_MAX but not handled above."); + return 0; }
ASSERT(zone <= U32_MAX);
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