Re: [PATCH V2] dmabuf: ensure unique directory name for dmabuf stats

[Christian König]

Am 10.05.22 um 19:14 schrieb Charan Teja Kalla:
> On 5/10/2022 8:42 PM, Christian König wrote:
> > >     * The information in the interface can also be used to derive
> > > per-exporter
> > >     * statistics. The data from the interface can be gathered on error
> > > conditions
> > > @@ -172,6 +172,7 @@ int dma_buf_stats_setup(struct dma_buf *dmabuf)
> > >    {
> > >        struct dma_buf_sysfs_entry *sysfs_entry;
> > >        int ret;
> > > +    static atomic64_t unique_id = ATOMIC_INIT(0);
> > Please move that to the beginning of the declarations.
> Done. Any scripts I can run at my end to catch these type of trivial
> changes? checkpatch.pl didn't report this coding style.

Not that I know of. It's also not a hard requirement, I let it mostly 
slip in the drivers I maintain. But upstream people sometimes insist on 
that, so I want to be clean at least in driver independent frameworks.

> > >          if (!dmabuf || !dmabuf->file)
> > >            return -EINVAL;
> > > @@ -192,7 +193,8 @@ int dma_buf_stats_setup(struct dma_buf *dmabuf)
> > >          /* create the directory for buffer stats */
> > >        ret = kobject_init_and_add(&sysfs_entry->kobj, &dma_buf_ktype,
> > > NULL,
> > > -                   "%lu", file_inode(dmabuf->file)->i_ino);
> > > +                   "%lu-%lu", file_inode(dmabuf->file)->i_ino,
> > Why not just use the unique value here? Or is the inode number necessary
> > for something?
> This will ease the debugging a lot. Given the dump, I can easily map
> which dmabuf buffer to the process. On the crashutilty I just have to
> search for this inode in the files output, just one example.

T.J. Mercier just confirmed my suspicion that this would break the UAPI. 
So that won't work.

This needs to be a single number, preferable documented as such.

Regards,
Christian.