fs/xfs/xfs_buf.c:1534 xfs_buf_submit_bio() warn: unsigned '_x' is never less than zero.

[David Laight]

On Mon, 17 Feb 2025 13:06:49 +0100
Alexandre Ghiti <alex at ghiti.fr> wrote:

> Hi Christoph,
> 
> On 17/02/2025 10:24, Christoph Hellwig wrote:
> > On Mon, Feb 17, 2025 at 01:53:08PM +0800, kernel test robot wrote:  
> >> New smatch warnings:
> >> fs/xfs/xfs_buf.c:1534 xfs_buf_submit_bio() warn: unsigned '_x' is never less than zero.  
> > Looks like this is an issue in the riscv virt_to_page implementation
> > which also shows up in various other places.  Any chance this could get
> > fixed in the riscv code?  
> 
> 
> To me, the only test that could give rise to this warning is the last 
> part of:
> 
> #define is_linear_mapping(x) \
>          ((x) >= PAGE_OFFSET && (!IS_ENABLED(CONFIG_64BIT) || (x) < 
> PAGE_OFFSET + KERN_VIRT_SIZE))
> 
> But given that the config is a 32-bit config, it should not be evaluated 
> at all.
> 
> Could that be a false-positive and then an issue in smatch?

Why is smatch even looking.
The equivalent check in gcc has been moved to -W2 because of all false positives.

	David