Thanks Gustavo. I have already merged this into jfs-next. It was all I had queued up and I failed to push it in the last merge window to Linus. I'll make sure I get it in the next one.
https://github.com/kleikamp/linux-shaggy/commits/jfs-next Shaggy On 5/7/20 1:55 PM, Gustavo A. R. Silva wrote: > The current codebase makes use of the zero-length array language > extension to the C90 standard, but the preferred mechanism to declare > variable-length types such as these ones is a flexible array member[1][2], > introduced in C99: > > struct foo { > int stuff; > struct boo array[]; > }; > > By making use of the mechanism above, we will get a compiler warning > in case the flexible array does not occur last in the structure, which > will help us prevent some kind of undefined behavior bugs from being > inadvertently introduced[3] to the codebase from now on. > > Also, notice that, dynamic memory allocations won't be affected by > this change: > > "Flexible array members have incomplete type, and so the sizeof operator > may not be applied. As a quirk of the original implementation of > zero-length arrays, sizeof evaluates to zero."[1] > > sizeof(flexible-array-member) triggers a warning because flexible array > members have incomplete type[1]. There are some instances of code in > which the sizeof operator is being incorrectly/erroneously applied to > zero-length arrays and the result is zero. Such instances may be hiding > some bugs. So, this work (flexible-array member conversions) will also > help to get completely rid of those sorts of issues. > > This issue was found with the help of Coccinelle. > > [1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html > [2] https://github.com/KSPP/linux/issues/21 > [3] commit 76497732932f ("cxgb3/l2t: Fix undefined behaviour") > > Signed-off-by: Gustavo A. R. Silva <gustavo...@kernel.org> > --- > fs/jfs/jfs_dtree.c | 2 +- > fs/jfs/jfs_xattr.h | 4 ++-- > 2 files changed, 3 insertions(+), 3 deletions(-) > > diff --git a/fs/jfs/jfs_dtree.c b/fs/jfs/jfs_dtree.c > index 3acc954f7c04..837d42f61464 100644 > --- a/fs/jfs/jfs_dtree.c > +++ b/fs/jfs/jfs_dtree.c > @@ -2964,7 +2964,7 @@ struct jfs_dirent { > loff_t position; > int ino; > u16 name_len; > - char name[0]; > + char name[]; > }; > > /* > diff --git a/fs/jfs/jfs_xattr.h b/fs/jfs/jfs_xattr.h > index f0558b3348da..c50167a7bc50 100644 > --- a/fs/jfs/jfs_xattr.h > +++ b/fs/jfs/jfs_xattr.h > @@ -17,12 +17,12 @@ struct jfs_ea { > u8 flag; /* Unused? */ > u8 namelen; /* Length of name */ > __le16 valuelen; /* Length of value */ > - char name[0]; /* Attribute name (includes null-terminator) */ > + char name[]; /* Attribute name (includes null-terminator) */ > }; /* Value immediately follows name */ > > struct jfs_ea_list { > __le32 size; /* overall size */ > - struct jfs_ea ea[0]; /* Variable length list */ > + struct jfs_ea ea[]; /* Variable length list */ > }; > > /* Macros for defining maxiumum number of bytes supported for EAs */ > > > > _______________________________________________ > Jfs-discussion mailing list > jfs-discuss...@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/jfs-discussion >
