| Message ID | 20171004221157.GL25517@bhelgaas-glaptop.roam.corp.google.com (mailing list archive) |
|---|---|
| State | New, archived |
| Delegated to: | Bjorn Helgaas |
| Headers | show |
On Thursday, October 5, 2017 12:11:57 AM CEST Bjorn Helgaas wrote: > On Sat, Sep 30, 2017 at 10:12:06AM +0800, Qiang Zheng wrote: > > PCIe PME and hot plug share same interrupt number. In some special case, > > Link down event cause hot plug interrupt, devices is not disconnected, > > But read config will return 0xff. > > > > In that case, PME work function will run and not return Because > > Root Status PME bit always 1 and can not be cleared. > > > > This patch add Root Status check in PME interrupt handler, > > Just do same as pciehp isr Slot status check. > > > > Signed-off-by: Qiang Zheng <zhengqiang10@huawei.com> > > --- > > drivers/pci/pcie/pme.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/drivers/pci/pcie/pme.c b/drivers/pci/pcie/pme.c > > index fafdb16..2ff2e57 100644 > > --- a/drivers/pci/pcie/pme.c > > +++ b/drivers/pci/pcie/pme.c > > @@ -273,7 +273,7 @@ static irqreturn_t pcie_pme_irq(int irq, void *context) > > spin_lock_irqsave(&data->lock, flags); > > pcie_capability_read_dword(port, PCI_EXP_RTSTA, &rtsta); > > > > - if (!(rtsta & PCI_EXP_RTSTA_PME)) { > > + if (rtsta == U32_MAX || !(rtsta & PCI_EXP_RTSTA_PME)) { > > spin_unlock_irqrestore(&data->lock, flags); > > return IRQ_NONE; > > } > > > > I applied the patch below to pci/misc for v4.15. > > I think we need a similar test in pcie_pme_work_fn() itself. Without > it, I think there's a race: if we get a legitimate PME, enter > pcie_pme_work_fn(), and the link goes down, we could still get > 0xffffffff the next time we read PCI_EXP_RTSTA. > > I also used "(u32) ~0" instead of U32_MAX because that's the style > used elsewhere. It might be clunkier than necessary, but U32_MAX > suggests a limit, and that's not really the concept here. > > I didn't add your reviewed-by, Rafael, since I made non-trivial > changes to the patch. > > Bjorn > > > > commit 303029d6d55ba10a37c82c31a89eb5550cde77ec > Author: Qiang <zhengqiang10@huawei.com> > Date: Thu Sep 28 11:54:34 2017 +0800 > > PCI/PME: Handle invalid data when reading Root Status > > PCIe PME and native hotplug share the same interrupt number, so hotplug > interrupts are also processed by PME. In some cases, e.g., a Link Down > interrupt, a device may be present but unreachable, so when we try to > read its Root Status register, the read fails and we get all ones data > (0xffffffff). > > Previously, we interpreted that data as PCI_EXP_RTSTA_PME being set, i.e., > "some device has asserted PME," so we scheduled pcie_pme_work_fn(). This > caused an infinite loop because pcie_pme_work_fn() tried to handle PME > requests until PCI_EXP_RTSTA_PME is cleared, but with the link down, > PCI_EXP_RTSTA_PME can't be cleared. > > Check for the invalid 0xffffffff data everywhere we read the Root Status > register. > > 1469d17dd341 ("PCI: pciehp: Handle invalid data when reading from > non-existent devices") added similar checks in the hotplug driver. > > Signed-off-by: Qiang Zheng <zhengqiang10@huawei.com> > [bhelgaas: changelog, also check in pcie_pme_work_fn(), use "~0" to follow > other similar checks] > Signed-off-by: Bjorn Helgaas <bhelgaas@google.com> > > diff --git a/drivers/pci/pcie/pme.c b/drivers/pci/pcie/pme.c > index fafdb165dd2e..df290aa58dce 100644 > --- a/drivers/pci/pcie/pme.c > +++ b/drivers/pci/pcie/pme.c > @@ -226,6 +226,9 @@ static void pcie_pme_work_fn(struct work_struct *work) > break; > > pcie_capability_read_dword(port, PCI_EXP_RTSTA, &rtsta); > + if (rtsta == (u32) ~0) > + break; > + > if (rtsta & PCI_EXP_RTSTA_PME) { > /* > * Clear PME status of the port. If there are other > @@ -273,7 +276,7 @@ static irqreturn_t pcie_pme_irq(int irq, void *context) > spin_lock_irqsave(&data->lock, flags); > pcie_capability_read_dword(port, PCI_EXP_RTSTA, &rtsta); > > - if (!(rtsta & PCI_EXP_RTSTA_PME)) { > + if (rtsta == (u32) ~0 || !(rtsta & PCI_EXP_RTSTA_PME)) { > spin_unlock_irqrestore(&data->lock, flags); > return IRQ_NONE; > } > FWIW, it looks OK to me. Thanks, Rafael
diff --git a/drivers/pci/pcie/pme.c b/drivers/pci/pcie/pme.c index fafdb165dd2e..df290aa58dce 100644 --- a/drivers/pci/pcie/pme.c +++ b/drivers/pci/pcie/pme.c @@ -226,6 +226,9 @@ static void pcie_pme_work_fn(struct work_struct *work) break; pcie_capability_read_dword(port, PCI_EXP_RTSTA, &rtsta); + if (rtsta == (u32) ~0) + break; + if (rtsta & PCI_EXP_RTSTA_PME) { /* * Clear PME status of the port. If there are other @@ -273,7 +276,7 @@ static irqreturn_t pcie_pme_irq(int irq, void *context) spin_lock_irqsave(&data->lock, flags); pcie_capability_read_dword(port, PCI_EXP_RTSTA, &rtsta); - if (!(rtsta & PCI_EXP_RTSTA_PME)) { + if (rtsta == (u32) ~0 || !(rtsta & PCI_EXP_RTSTA_PME)) { spin_unlock_irqrestore(&data->lock, flags); return IRQ_NONE; }