Messages in this thread | | | Date | Tue, 7 Aug 2007 00:24:37 -0700 | From | Andrew Morton <> | Subject | Re: [PATCH] pci_get_device call from interrupt in reboot fixups |
| |
On Mon, 6 Aug 2007 19:49:10 -0700 Greg KH <gregkh@suse.de> wrote:
> On Mon, Aug 06, 2007 at 11:16:20AM +0400, Denis V. Lunev wrote: > > Greg KH wrote: > > > On Fri, Aug 03, 2007 at 02:39:24PM +0400, Denis V. Lunev wrote: > > >> The following calltrace is possible now: > > >> handle_sysrq > > >> machine_emergency_restart > > >> mach_reboot_fixups > > >> pci_get_device > > >> pci_get_subsys > > >> down_read > > >> The patch obtains PCI device during initialization to avoid bothering PCI > > >> search engine in interrupt. Devices used in this code are not supposed to > > >> be pluggable, so it looks safe to keep them. > > > > > > What devices are supposed to be affected here? Are you sure that they > > > can't be removed later? Grabbing references here might mess with them > > > in the future. > > Right now the list is the following: > > static struct device_fixup fixups_table[] = { > > { PCI_VENDOR_ID_CYRIX, PCI_DEVICE_ID_CYRIX_5530_LEGACY, > > cs5530a_warm_reset }, > > { PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_CS5536_ISA, cs5536_warm_reset }, > > }; > > > > Though, if the approach is not suitable, we can skip fixups if we came > > from sysrq. > > I don't think we really need to do fixups when we are "crashing" like > this. The user really isn't shutting down the kernel as it should > normally do. > > Andrew, I really don't want to change the PCI core to handle this, as we > finally fixed a lot of issues with drivers trying to walk these lists > from interrupt context. So if you want to just hide the warning message > as we are shutting down, that's fine with me. Or just don't do the > fixups. But grabbing a reference to the pci device is unsafe in my > opinion and I do not want to do that. >
OK, good decision ;)
One approach would be for some brave soul to pick his way through the reboot code and ensure that we are correctly and reliably setting system_state to SYSTEM_RESTART, then test that in __might_sleep().
But this does suppress somewhat-useful debugging just because of sysrq-B and I really wouldn't want to utilise the horrid system_state any more that we are presently doing. I think on balance that it would be better if we could do something more targetted, like modify emergency_restart() to test in_interrupt() and to then apologetically set some well-named global flag which will shut up __might_sleep(). Pretty foul, but I can't think of anything better.
- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |