Re: [PATCH 13/13] xfs: convert xfs_sysfs attrs to use ->seq_show

[Greg Kroah-Hartman]

On Tue, Sep 14, 2021 at 05:30:11PM +0200, Christoph Hellwig wrote:
> On Tue, Sep 14, 2021 at 05:28:08PM +0200, Greg Kroah-Hartman wrote:
> > We can "force" it by not allowing buffers to be bigger than that, which
> > is what the code has always done.  I think we want to keep that for now
> > and not add the new seq_show api.
> 
> The buffer already is not larger than that.  The problem is that
> sysfs_emit does not actually work for the non-trivial attributes,
> which generally are the source of bugs.

They huge majority of sysfs attributes are "trivial".  So for maybe at
least 95% of the users, if not more, using sysfs_emit() is just fine as
all you "should" be doing is emitting a single value.

For those that are non-trivial, yes, that will be harder, but as the xfs
discussion shows, those are not normal at all, and I do not want to make
creating them easier as that is not the model that sysfs was designed
for if at all possible.

thanks,

greg k-h