On Wed, Jun 13, 2018 at 08:32:13PM +0000, Dexuan Cui wrote: > > From: Dexuan Cui > > Sent: Wednesday, June 6, 2018 17:15 > > To: Haiyang Zhang <haiyangz@xxxxxxxxxxxxx>; Lorenzo Pieralisi > > <lorenzo.pieralisi@xxxxxxx>; Bjorn Helgaas <bhelgaas@xxxxxxxxxx>; > > linux-pci@xxxxxxxxxxxxxxx; KY Srinivasan <kys@xxxxxxxxxxxxx>; Stephen > > Hemminger <sthemmin@xxxxxxxxxxxxx>; olaf@xxxxxxxxx; > > apw@xxxxxxxxxxxxx; jasowang@xxxxxxxxxx > > Cc: linux-kernel@xxxxxxxxxxxxxxx; driverdev-devel@xxxxxxxxxxxxxxxxxxxxxx; > > vkuznets@xxxxxxxxxx; marcelo.cerri@xxxxxxxxxxxxx > > Subject: RE: [PATCH] PCI: hv: Fix a __local_bh_enable_ip warning in > > hv_compose_msi_msg() > > > > > From: Haiyang Zhang > > > Sent: Friday, May 25, 2018 12:52 > > > To: Dexuan Cui <decui@xxxxxxxxxxxxx>; Lorenzo Pieralisi > > > <lorenzo.pieralisi@xxxxxxx>; Bjorn Helgaas <bhelgaas@xxxxxxxxxx>; > > > linux-pci@xxxxxxxxxxxxxxx; KY Srinivasan <kys@xxxxxxxxxxxxx>; Stephen > > > Hemminger <sthemmin@xxxxxxxxxxxxx>; olaf@xxxxxxxxx; > > > apw@xxxxxxxxxxxxx; jasowang@xxxxxxxxxx > > > Cc: linux-kernel@xxxxxxxxxxxxxxx; driverdev-devel@xxxxxxxxxxxxxxxxxxxxxx; > > > vkuznets@xxxxxxxxxx; marcelo.cerri@xxxxxxxxxxxxx > > > Subject: RE: [PATCH] PCI: hv: Fix a __local_bh_enable_ip warning in > > > hv_compose_msi_msg() > > > > > > > From: Dexuan Cui > > > > Sent: Tuesday, May 22, 2018 8:18 PM > > > > To: Lorenzo Pieralisi <lorenzo.pieralisi@xxxxxxx>; Bjorn Helgaas > > > > <bhelgaas@xxxxxxxxxx>; linux-pci@xxxxxxxxxxxxxxx; KY Srinivasan > > > > <kys@xxxxxxxxxxxxx>; Stephen Hemminger <sthemmin@xxxxxxxxxxxxx>; > > > > olaf@xxxxxxxxx; apw@xxxxxxxxxxxxx; jasowang@xxxxxxxxxx > > > > Cc: linux-kernel@xxxxxxxxxxxxxxx; driverdev-devel@xxxxxxxxxxxxxxxxxxxxxx; > > > > Haiyang Zhang <haiyangz@xxxxxxxxxxxxx>; vkuznets@xxxxxxxxxx; > > > > marcelo.cerri@xxxxxxxxxxxxx > > > > Subject: [PATCH] PCI: hv: Fix a __local_bh_enable_ip warning in > > > > hv_compose_msi_msg() > > > > > > > > > > > > Commit de0aa7b2f97d ("PCI: hv: Fix 2 hang issues in > > > hv_compose_msi_msg()") > > > > uses local_bh_disable()/enable(), because hv_pci_onchannelcallback() can > > > also > > > > run in tasklet context as the channel event callback. > > > > > > > > With CONFIG_PROVE_LOCKING=y in the latest mainline, or old kernels that > > > > don't have commit f71b74bca637 ("irq/softirqs: Use lockdep to assert IRQs > > > are > > > > disabled/enabled"), it turns out can we trigger a warning at the beginning > > of > > > > __local_bh_enable_ip(), because the upper layer irq code can call > > > > hv_compose_msi_msg() with local irqs disabled. > > > > > > > > Let's fix the warning by switching to local_irq_save()/restore(). This is not an > > > > issue because hv_pci_onchannelcallback() is not slow, and it not a hot path. > > > > > > > > Fixes: de0aa7b2f97d ("PCI: hv: Fix 2 hang issues in > > hv_compose_msi_msg()") > > > > Signed-off-by: Dexuan Cui <decui@xxxxxxxxxxxxx> > > > > Cc: <stable@xxxxxxxxxxxxxxx> > > > > Cc: Stephen Hemminger <sthemmin@xxxxxxxxxxxxx> > > > > Cc: K. Y. Srinivasan <kys@xxxxxxxxxxxxx> > > > > --- > > > > > > Reviewed-by: Haiyang Zhang <haiyangz@xxxxxxxxxxxxx> > > > > > > Thanks you. > > > > Hi Lorenzo, > > > > Can I have your reply to this patch? > > > > -- Dexuan > > It looks Lorenzo's pci.git tree has not been updated for 3+ weeks. > I guess Lorenzo may be on vacation. > > @Bjorn, can this patch go through your tree? > Should I resubmit it? No need to resubmit it, Lorenzo has been out for a bit, but I'm sure he'll pick this up as he catches up. You might, however, fix the commit log: This is not an issue because hv_pci_onchannelcallback() is not slow, and it not a hot path. This has at least one typo (I think you mean "and *is* not a hot path"). I also don't understand the sentence as a whole because the hv_pci_onchannelcallback() comment says it's called whenever the host sends a packet to this channel, and that *does* sound like a hot path. I also don't understand the "hv_pci_onchannelcallback() is not slow" part. In other words, you're saying hv_pci_onchannelcallback() is fast and it's not a hot path. And apparently this has something to do with the difference between local_bh_disable() and local_irq_save()? Bjorn _______________________________________________ devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxx http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel