linux-kernel - Re: mhi resume failure on reboot with 6.13-rc2

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20241218140910.ysovysnvns26vbmd@thinkpad>
Date: Wed, 18 Dec 2024 19:39:10 +0530
From: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
To: Johan Hovold <johan@...nel.org>
Cc: mhi@...ts.linux.dev, linux-arm-msm@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Loic Poulain <loic.poulain@...aro.org>
Subject: Re: mhi resume failure on reboot with 6.13-rc2

On Wed, Dec 18, 2024 at 02:55:02PM +0100, Johan Hovold wrote:
> On Wed, Dec 18, 2024 at 06:00:19PM +0530, Manivannan Sadhasivam wrote:
> > On Wed, Dec 18, 2024 at 01:02:39PM +0100, Johan Hovold wrote:
> > > On Wed, Dec 18, 2024 at 05:08:30PM +0530, Manivannan Sadhasivam wrote:
> > > > On Wed, Dec 18, 2024 at 09:40:45AM +0100, Johan Hovold wrote:
> > > 
> > > > > I've tracked down the hang to a deadlock on the parent device lock.
> > > > > 
> > > > > Driver core takes the parent device lock before calling shutdown(), and
> > > > > then mhi_pci_shutdown() waits indefinitely for the recovery thread to
> > > > > finish.
> > > 
> > > > Thanks for tracking the deadlock. I think we should use pci_try_reset_function()
> > > > instead of pci_reset_function() in mhi_pci_recovery_work().
> > > > 
> > > > If the pci_dev_lock() is already taken, it will return with -EAGAIN and we do
> > > > not need to worry in that case since the host is going to be powered off anyway
> > > > (and so the device).
> > > 
> > > That may work. But note that I've now also seen this deadlock during
> > > suspend (i.e. when the device is not going away). The
> > > pci_try_reset_function() should avoid the deadlock here too, but we'll
> > > end up in funny state.
> > 
> > Hopefully, recovery_work() started by mhi_pci_runtime_resume() would be able to
> > reset the device.
> 
> But that's not going to happen as that reset is what is currently
> causing the deadlock and which would simply be skipped if you switch to
> pci_try_reset_function().
> 

mhi_pci_runtime_resume() will queue the recovery_work() and return. So I was
hoping that by the time pci_try_reset_function() is called, the lock would be
available.

- Mani

-- 
மணிவண்ணன் சதாசிவம்