Re: [RFT PATCH v3 1/1] usb: hub: Fix flushing of delayed work used for post resume purposes

[Greg KH <gregkh@linuxfoundation.org>]

On Mon, Jun 30, 2025 at 01:07:29PM +0300, Mathias Nyman wrote:
> On 28.6.2025 17.46, Greg KH wrote:
> > On Fri, Jun 27, 2025 at 07:43:48PM +0300, Mathias Nyman wrote:
> > > Delayed work that prevents USB3 hubs from runtime-suspending too early
> > > needed to be flushed in hub_quiesce() to resolve issues detected on
> > > QC SC8280XP CRD board during suspend resume testing.
> > > 
> > > This flushing did however trigger new issues on Raspberry Pi 3B+, which
> > > doesn't have USB3 ports, and doesn't queue any post resume delayed work.
> > > 
> > > The flushed 'hub->init_work' item is used for several purposes, and
> > > is originally initialized with a 'NULL' work function. The work function
> > > is also changed on the fly, which may contribute to the issue.
> > > 
> > > Solve this by creating a dedicated delayed work item for post resume work,
> > > and flush that delayed work in hub_quiesce()
> > > 
> > > Cc: stable@kernel.org
> > > Fixes: a49e1e2e785f ("usb: hub: Fix flushing and scheduling of delayed work that tunes runtime pm")
> > > Reported-by: Mark Brown <broonie@kernel.org>
> > > Closes: https://lore.kernel.org/linux-usb/aF5rNp1l0LWITnEB@finisterre.sirena.org.uk
> > > Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
> > > ---
> > > v3:
> > >   - Rebase on top of a49e1e2e785f ("usb: hub: Fix flushing and scheduling of delayed work that tunes runtime pm")
> > >   - Rewrite commit message
> > > 
> > > v2:
> > >   - Add and use dedicated delayed work struct for post resume work
> > >   - Add commit message section about dedicated work
> > 
> > This seems to work, want me to take this, or are you going to submit
> > another one?  I'll hold off on sending the pull request to Linus for
> > -rc4 because of this.
> > 
> > thanks,
> > 
> > greg k-h
> 
> Sorry about the response delay, was offline during weekend

As one should be!  :)

> I'll do some quick additional smoketests, suspending and disconnecting runtime suspended
> chained USB3 hubs. Shouldn't take more than a couple of hours

Ok, no rush, thanks for letting me know.

greg k-h