[+cc Rafael, linux-pm] Hi Jia-Ju,
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. We can either - change pci_set_power_state() so it can be called while holding a spinlock (as this patch does), or - change the drivers so they don't hold the spinlock while calling pci_set_power_state(). I think the latter is better because d3cold_delay is typically 100ms, and that's a long time to spin with interrupts disabled. I assume it's easy to produce an actual failure here? Why haven't we seen bug reports about this? Bjorn > Signed-off-by: Jia-Ju Bai <baijiaju1...@163.com> > --- > drivers/pci/pci.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c > index 6078dfc..7b763a3 100644 > --- a/drivers/pci/pci.c > +++ b/drivers/pci/pci.c > @@ -823,7 +823,7 @@ static void __pci_start_power_transition(struct pci_dev > *dev, pci_power_t state) > */ > if (dev->runtime_d3cold) { > if (dev->d3cold_delay) > - msleep(dev->d3cold_delay); > + mdelay(dev->d3cold_delay); > /* > * When powering on a bridge from D3cold, the > * whole hierarchy may be powered on into > -- > 1.7.9.5 > > _______________________________________________ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel