Re: CVS commit: src/sys/ufs/lfs

[Konrad Schroder <perseant%hhhh.org@localhost>]

The loop has to run because the head of the free list at this point can 
never be LFS_UNUSED_INUM; but there is no way for GCC to know that.  
I'll patch it momentarily.

Thanks,

-Konrad

On 9/15/2025 10:49 AM, David Holland wrote:
> On Mon, Sep 15, 2025 at 04:15:00AM +0000, Konrad Schroder wrote:
>   > Modified Files:
>   > 	src/sys/ufs/lfs: lfs.h lfs_accessors.h lfs_alloc.c
>   >
>   > Log Message:
>   > If setting the head (or tail) of the inode free list to LFS_UNUSED_INUM, also
>   > set the tail (resp. head) to LFS_UNUSED_INUM, as the list is now empty.
>   >
>   > Add a check to ensure that lfs_valloc_fixed will always terminate, even
>   > if the free list should contain a loop.  Extend the ifile at the end if it
>   > is empty, to match the assumption of lfs_valloc() that the free list is
>   > never empty.
>   >
>   > Needed for roll-forward.
>
> This seems to have resulted in build breakages on platforms where gcc
> fails to realize that the loop involved runs at least once, e.g.
> https://releng.netbsd.org/builds/HEAD/20250915064210Z/sparc64.build.failed
>
>     lfs_alloc.c:407:20: error: 'nextfree' may be used uninitialized
>
> although looking at it I'm not immediately sure that the loop _does_
> run at least once, so I'm reluctant to try to hack in a fix in a rush.
>
> Can you attend to it? :-|