Messages in this thread | | | Date | Fri, 19 May 2017 11:10:10 -0700 | From | Liu Bo <> | Subject | Re: [PATCH] Btrfs: work around maybe-uninitialized warning |
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On Thu, May 18, 2017 at 03:33:29PM +0200, Arnd Bergmann wrote: > A rewrite of btrfs_submit_direct_hook appears to have introduced a warning: > > fs/btrfs/inode.c: In function 'btrfs_submit_direct_hook': > fs/btrfs/inode.c:8467:14: error: 'bio' may be used uninitialized in this function [-Werror=maybe-uninitialized] > > Where the 'bio' variable was previously initialized unconditionally, it > is now set in the "while (submit_len > 0)" loop that would never execute > if submit_len is zero. > > Assuming this cannot happen in practice, we can avoid the warning > by simply replacing the while{} loop with a do{}while() loop so > the compiler knows that it will always be entered at least once. >
Thanks for the fix. I think it's a false positve one and I've updated it in v2 with a 'struct bio *bio = NULL' to make compiler happy, could you please help reveiw it?
Thanks, -liubo
> Fixes: 0fd27e06c61b ("Btrfs: use bio_clone_bioset_partial to simplify DIO submit") > Signed-off-by: Arnd Bergmann <arnd@arndb.de> > --- > --- > fs/btrfs/inode.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c > index 8c37b4fa4cbb..c62cf9593cb3 100644 > --- a/fs/btrfs/inode.c > +++ b/fs/btrfs/inode.c > @@ -8497,7 +8497,7 @@ static int btrfs_submit_direct_hook(struct btrfs_dio_private *dip, > /* bio split */ > ASSERT(map_length <= INT_MAX); > atomic_inc(&dip->pending_bios); > - while (submit_len > 0) { > + do { > clone_len = min_t(int, submit_len, map_length); > > /* > @@ -8540,7 +8540,7 @@ static int btrfs_submit_direct_hook(struct btrfs_dio_private *dip, > start_sector << 9, &map_length, NULL, 0); > if (ret) > goto out_err; > - } > + } while (submit_len > 0); > > submit: > ret = __btrfs_submit_dio_bio(bio, inode, file_offset, skip_sum, > -- > 2.9.0 >
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