On Wed, May 02, 2012 at 03:25:21PM +0800, Jiang Liu wrote: > On 2012-5-2 13:00, Greg KH wrote: > >On Fri, Apr 27, 2012 at 11:16:43PM +0800, Jiang Liu wrote: > >>From: Jiang Liu<jiang.liu@xxxxxxxxxx> > >> > >>There are multiple ways to trigger PCI hotplug requests concurrently, > >>such as: > >>1. Sysfs interfaces exported by the PCI core subsystem > >>2. Sysfs interfaces exported by the PCI hotplug subsystem > >>3. PCI hotplug events triggered by PCI Hotplug Controllers > >>4. ACPI hotplug events for PCI host bridges > >>5. Driver binding/unbinding events > >> > >>The PCI core subsystem doesn't support concurrent hotplug operations yet, > >>so all PCI hotplug requests should be globally serialized. This patch > >>introduces several new interfaces to serialize PCI hotplug operations. > >> > >>pci_hotplug_try_enter(): try to acquire write lock > > > >Ick, no, why would you ever want to do that? > > > >>pci_hotplug_enter(): acquire write lock > >>pci_hotplug_exit(): release write lock > >>pci_hotplug_disable(): acquire read lock > >>pci_hotplug_enable(): release read lock > > > >No, the pci hotplug core should not need a rwsem, just a simple lock, if > >that: > > pci_hotplug_lock() > > pci_hotplug_unlock() > >and that's it. > > > >Really you should not need these functions, the pci hotplug core should > >handle it for you, and the drivers should not care at all. That's the > >"proper" way to fix this up, serialize stuff within the pci core, not > >the individual drivers. > > > >>Today we have reproduced the issue on a real platform by using > >>acpiphp driver. It's an IA64 platform running Suse 11SP1 (official > >>2.6.32.12 kernel). The test script is: > >> > >>This issue could be reproduced on an IA64 platform with Suse 11SP1 > >>(official 2.6.32.12 kernel) and acpiphp driver. > > > >You do realize just how old that kernel is right? Please don't assume > >that this kernel version is relevant to us all these years later. > This could be reproduced with latest kernel too, such as 3.3. We > use 2.6.32.12 because the all 3.x series kernels can't boot on > our IA64 platform due to an issue in scheduler. We have reproduced > similar issue on x86 platforms with 3.x kernels. That's wonderful, and is relevant, unlike what you originally wrote. Please always write relevant changelog comments, otherwise they are... greg k-h -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
