| Message ID | 20240729200608.10722-1-dsterba@suse.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | btrfs: initialize location to fix -Wmaybe-uninitialized in btrfs_lookup_dentry() | expand |
在 2024/7/30 05:36, David Sterba 写道: > Some arch + compiler combinations report a potentially unused variable > location in btrfs_lookup_dentry(). This is a false alert as the variable > is passed by value and always valid or there's an error. The compilers > cannot probably reason about that although btrfs_inode_by_name() is in > the same file. > > > + /kisskb/src/fs/btrfs/inode.c: error: 'location.objectid' may be used > +uninitialized in this function [-Werror=maybe-uninitialized]: => 5603:9 > > + /kisskb/src/fs/btrfs/inode.c: error: 'location.type' may be used > +uninitialized in this function [-Werror=maybe-uninitialized]: => 5674:5 > > m68k-gcc8/m68k-allmodconfig > mips-gcc8/mips-allmodconfig > powerpc-gcc5/powerpc-all{mod,yes}config > powerpc-gcc5/ppc64_defconfig > > Initialize it to zero, this should fix the warnings and won't change the > behaviour as btrfs_inode_by_name() accepts only a root or inode item > types, otherwise returns an error. > > Reported-by: Geert Uytterhoeven <geert@linux-m68k.org> > Link: https://lore.kernel.org/linux-btrfs/bd4e9928-17b3-9257-8ba7-6b7f9bbb639a@linux-m68k.org/ > Signed-off-by: David Sterba <dsterba@suse.com> Reviewed-by: Qu Wenruo <wqu@suse.com> Although I hate to update our code for bad compilers, I guess it's unavoidable anyway. Thanks, Qu > --- > fs/btrfs/inode.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c > index 32010127710d..333b0e8587a2 100644 > --- a/fs/btrfs/inode.c > +++ b/fs/btrfs/inode.c > @@ -5667,7 +5667,7 @@ struct inode *btrfs_lookup_dentry(struct inode *dir, struct dentry *dentry) > struct inode *inode; > struct btrfs_root *root = BTRFS_I(dir)->root; > struct btrfs_root *sub_root = root; > - struct btrfs_key location; > + struct btrfs_key location = { 0 }; > u8 di_type = 0; > int ret = 0; >
On Tue, Jul 30, 2024 at 07:04:36AM +0930, Qu Wenruo wrote: > > > 在 2024/7/30 05:36, David Sterba 写道: > > Some arch + compiler combinations report a potentially unused variable > > location in btrfs_lookup_dentry(). This is a false alert as the variable > > is passed by value and always valid or there's an error. The compilers > > cannot probably reason about that although btrfs_inode_by_name() is in > > the same file. > > > > > + /kisskb/src/fs/btrfs/inode.c: error: 'location.objectid' may be used > > +uninitialized in this function [-Werror=maybe-uninitialized]: => 5603:9 > > > + /kisskb/src/fs/btrfs/inode.c: error: 'location.type' may be used > > +uninitialized in this function [-Werror=maybe-uninitialized]: => 5674:5 > > > > m68k-gcc8/m68k-allmodconfig > > mips-gcc8/mips-allmodconfig > > powerpc-gcc5/powerpc-all{mod,yes}config > > powerpc-gcc5/ppc64_defconfig > > > > Initialize it to zero, this should fix the warnings and won't change the > > behaviour as btrfs_inode_by_name() accepts only a root or inode item > > types, otherwise returns an error. > > > > Reported-by: Geert Uytterhoeven <geert@linux-m68k.org> > > Link: https://lore.kernel.org/linux-btrfs/bd4e9928-17b3-9257-8ba7-6b7f9bbb639a@linux-m68k.org/ > > Signed-off-by: David Sterba <dsterba@suse.com> > > Reviewed-by: Qu Wenruo <wqu@suse.com> > > Although I hate to update our code for bad compilers, I guess it's > unavoidable anyway. Yeah, but the number of such fixups is bearable, we have added like one per release.
Hi David, On Mon, Jul 29, 2024 at 10:06 PM David Sterba <dsterba@suse.com> wrote: > Some arch + compiler combinations report a potentially unused variable > location in btrfs_lookup_dentry(). This is a false alert as the variable > is passed by value and always valid or there's an error. The compilers > cannot probably reason about that although btrfs_inode_by_name() is in > the same file. > > > + /kisskb/src/fs/btrfs/inode.c: error: 'location.objectid' may be used > +uninitialized in this function [-Werror=maybe-uninitialized]: => 5603:9 > > + /kisskb/src/fs/btrfs/inode.c: error: 'location.type' may be used > +uninitialized in this function [-Werror=maybe-uninitialized]: => 5674:5 > > m68k-gcc8/m68k-allmodconfig > mips-gcc8/mips-allmodconfig > powerpc-gcc5/powerpc-all{mod,yes}config > powerpc-gcc5/ppc64_defconfig > > Initialize it to zero, this should fix the warnings and won't change the > behaviour as btrfs_inode_by_name() accepts only a root or inode item > types, otherwise returns an error. > > Reported-by: Geert Uytterhoeven <geert@linux-m68k.org> > Link: https://lore.kernel.org/linux-btrfs/bd4e9928-17b3-9257-8ba7-6b7f9bbb639a@linux-m68k.org/ > Signed-off-by: David Sterba <dsterba@suse.com> > --- > fs/btrfs/inode.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c > index 32010127710d..333b0e8587a2 100644 > --- a/fs/btrfs/inode.c > +++ b/fs/btrfs/inode.c > @@ -5667,7 +5667,7 @@ struct inode *btrfs_lookup_dentry(struct inode *dir, struct dentry *dentry) > struct inode *inode; > struct btrfs_root *root = BTRFS_I(dir)->root; > struct btrfs_root *sub_root = root; > - struct btrfs_key location; > + struct btrfs_key location = { 0 }; > u8 di_type = 0; > int ret = 0; > Thanks, this gets rid of the failure for m68k/allmodconfig (gcc version 8.4.0 (Ubuntu 8.4.0-3ubuntu1) and 9.5.0 (Ubuntu 9.5.0-1ubuntu1~22.04)). On m68k, it didn't show up with gcc 10, 11, and 12. Also, enabling CONFIG_CC_OPTIMIZE_FOR_SIZE fixed it for gcc 8/9. Tested-by: Geert Uytterhoeven <geert@linux-m68k.org> Gr{oetje,eeting}s, Geert
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index 32010127710d..333b0e8587a2 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -5667,7 +5667,7 @@ struct inode *btrfs_lookup_dentry(struct inode *dir, struct dentry *dentry) struct inode *inode; struct btrfs_root *root = BTRFS_I(dir)->root; struct btrfs_root *sub_root = root; - struct btrfs_key location; + struct btrfs_key location = { 0 }; u8 di_type = 0; int ret = 0;