Re: [RFC Patch] sysfs: add marks for mutable sysfs files

[Cong Wang]

Eric W. Biederman wrote:
> Amerigo Wang <amwang@xxxxxxxxxx> writes:
>
> > NOTE: This patch is only a draft, not ready to be taken.
> >
> > This fixes all the s_active related bogus lockdep warnings that I received,
> > I already tested it, it works fine for cpu hotplug, I/O scheduler switch,
> > and suspend.
> >
> > This patch introduces sever sysfs/kobject interfaces to add mutable
> > sysfs files or kobjects, those files could be removed by the kernel
> > during some event, e.g. cpu hotplug. All of this kind of sysfs files
> > should use these API's, to avoid the deadlock warnings.
> >
> > I am still not sure if this is the best fix.
> >
> > Please comment.
>
> mutable as you describe it happens to be the common case, and that
> class of files is not free from this class of problem.
>
> Your patch is actively wrong if it solves the i/o scheduler issue,
> as those files are in fact mutable by your definition, block devices
> are hot pluggable.
>
> Having a special case for permanent sysfs files, that we refuse to
> delete would be reasonable, but it certainly does not cover
> everything.

(Sorry for the delay, we are having Chinese new year here.)

Oh, yes, I just worried that if my patch is aggressive.
I saw your patch, will have a review now.

Thank you!

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