Re: [PATCH] pci: Fix a possible sleep-in-atomic bug in pci_set_power_state

[Jia-Ju Bai]

Oh, sorry, I will send the patches for each driver.


Thanks,
Jia-Ju Bai

On 2017/10/9 16:17, Greg KH wrote:
> On Mon, Oct 09, 2017 at 04:16:20PM +0800, Jia-Ju Bai wrote:
> > The drivers vt6655 and gma500 call pci_set_power_state under a spinlock, which may sleep.
> > The function call paths are:
> > gma_power_begin (acquire the spinlock) (drivers/gpu/drm/gma500/power.c)
> >    gma_resume_pci
> >      pci_set_power_state
> >        __pci_start_power_transition (drivers/pci/pci.c)
> >          msleep --> may sleep
> >
> > gma_power_begin (acquire the spinlock) (drivers/gpu/drm/gma500/power.c)
> >    gma_resume_pci
> >      pci_enable_device
> >        pci_enable_device_flags (drivers/pci/pci.c)
> >          do_pci_enable_device
> >            pci_set_power_state
> >              __pci_start_power_transition
> >                msleep --> may sleep
> >
> > vt6655_suspend (acquire the spinlock) (drivers/staging/vt6655/device_main.c)
> >    pci_set_power_state
> >      __pci_start_power_transition (drivers/pci/pci.c)
> >        msleep --> may sleep
> >
> > To fix these bugs, msleep is replaced with mdelay in __pci_start_power_transition
> >
> > These bugs are found by my static analysis tool and my code review.
> Wait, no, why not fix the callers to not have a spinlock.  Those are the
> only users of these calls that are doing so incorrectly, don't change
> the PCI core for the fault of 2 broken drivers.
>
> thanks,
>
> greg k-h