On Tue, Jul 03, 2018 at 07:40:46PM +0530, poza@xxxxxxxxxxxxxx wrote: > On 2018-07-03 19:29, Lukas Wunner wrote: > >On Tue, Jul 03, 2018 at 09:31:24AM -0400, Sinan Kaya wrote: > >>Issue is observing hotplug link down event in the middle of AER recovery > >>as in my previous reply. > >> > >>If we mask hotplug interrupts before secondary bus reset via my patch, > >>then hotplug driver will not observe both link up and link down > >>interrupts. > >> > >>If we don't mask hotplug interrupts, we have a race condition. > > > >I assume that a bus reset not only causes a link and presence event but > >also clears the Presence Detect State bit in the Slot Status register > >and the Data Link Layer Link Active bit in the Link Status register > >momentarily. > > > >pciehp may access those two bits concurrently to the AER driver > >performing a slot reset. So it may not be sufficient to mask > >the interrupt. > > > >I've posted this patch to address the issue: > >https://patchwork.ozlabs.org/patch/930391/ > > Was just wondering that you are protecting Presence Detect State bit with > reset_lock, mainly in pciehp_ist > but with hotplug interrupt disabled, is there another way that it hotplug > code gets activated ? The user may turn the slot on/off via sysfs. If an Attention Button is present, the user may also press that button to turn the slot on/off after 5 seconds. Either way, it may cause pciehp's IRQ thread to run concurrently to a reset initiated by the AER driver, independently of any events signalled by the slot. Thanks, Lukas
