| Message ID | 20190301161251.26774-1-s.miroshnichenko@yadro.com |
|---|---|
| State | Superseded |
| Delegated to: | Bjorn Helgaas |
| Headers | show |
| Series | PCI: pciehp: Fix re-enabling the slot marked for safe removal | expand |
On Fri, Mar 01, 2019 at 07:12:51PM +0300, Sergey Miroshnichenko wrote: > During the safe removal procedure, a Data Link Layer State Changed event > may occur after pciehp_power_off_slot(), and it is handled when the slot is > already set to OFF_STATE. This results in re-enabling the device and makes > it impossible to actually safely remove it. > > Add a check for a Presence Detect Changed bit to filter out this interrupt. > > It is still possible to re-enable the device if it remains in the slot > after pressing the Attention Button by pressing it again. > > Signed-off-by: Sergey Miroshnichenko <s.miroshnichenko@yadro.com> > Cc: Lukas Wunner <lukas@wunner.de> > --- > drivers/pci/hotplug/pciehp_ctrl.c | 8 ++++++++ > 1 file changed, 8 insertions(+) > > diff --git a/drivers/pci/hotplug/pciehp_ctrl.c b/drivers/pci/hotplug/pciehp_ctrl.c > index 3f3df4c29f6e..941f77b71df4 100644 > --- a/drivers/pci/hotplug/pciehp_ctrl.c > +++ b/drivers/pci/hotplug/pciehp_ctrl.c > @@ -251,6 +251,14 @@ void pciehp_handle_presence_or_link_change(struct controller *ctrl, u32 events) > return; > } > > + /* Handle the DLLSC from the slot which just has been turned off */ > + if ((events & PCI_EXP_SLTSTA_DLLSC) && > + !(events & PCI_EXP_SLTSTA_PDC) && > + present && !link_active) { > + mutex_unlock(&ctrl->state_lock); > + return; > + } > + > switch (ctrl->state) { > case BLINKINGON_STATE: > cancel_delayed_work(&ctrl->button_work); Hm, I'd instead prefer amending remove_board() like this: if (POWER_CTRL(ctrl)) { pciehp_power_off_slot(ctrl); /* * After turning power off, we must wait for at least 1 second * before taking any action that relies on power having been * removed from the slot/adapter. */ msleep(1000); + /* ignore link or presence changes caused by power off */ + atomic_and(~(PCI_EXP_SLTSTA_DLLSC | PCI_EXP_SLTSTA_PDC), + &ctrl->pending_events); } Would this work for you? Thanks, Lukas
On 3/5/19 2:01 PM, Lukas Wunner wrote: > On Fri, Mar 01, 2019 at 07:12:51PM +0300, Sergey Miroshnichenko wrote: >> During the safe removal procedure, a Data Link Layer State Changed event >> may occur after pciehp_power_off_slot(), and it is handled when the slot is >> already set to OFF_STATE. This results in re-enabling the device and makes >> it impossible to actually safely remove it. >> >> Add a check for a Presence Detect Changed bit to filter out this interrupt. >> >> It is still possible to re-enable the device if it remains in the slot >> after pressing the Attention Button by pressing it again. >> >> Signed-off-by: Sergey Miroshnichenko <s.miroshnichenko@yadro.com> >> Cc: Lukas Wunner <lukas@wunner.de> >> --- >> drivers/pci/hotplug/pciehp_ctrl.c | 8 ++++++++ >> 1 file changed, 8 insertions(+) >> >> diff --git a/drivers/pci/hotplug/pciehp_ctrl.c b/drivers/pci/hotplug/pciehp_ctrl.c >> index 3f3df4c29f6e..941f77b71df4 100644 >> --- a/drivers/pci/hotplug/pciehp_ctrl.c >> +++ b/drivers/pci/hotplug/pciehp_ctrl.c >> @@ -251,6 +251,14 @@ void pciehp_handle_presence_or_link_change(struct controller *ctrl, u32 events) >> return; >> } >> >> + /* Handle the DLLSC from the slot which just has been turned off */ >> + if ((events & PCI_EXP_SLTSTA_DLLSC) && >> + !(events & PCI_EXP_SLTSTA_PDC) && >> + present && !link_active) { >> + mutex_unlock(&ctrl->state_lock); >> + return; >> + } >> + >> switch (ctrl->state) { >> case BLINKINGON_STATE: >> cancel_delayed_work(&ctrl->button_work); > > Hm, I'd instead prefer amending remove_board() like this: > > if (POWER_CTRL(ctrl)) { > pciehp_power_off_slot(ctrl); > > /* > * After turning power off, we must wait for at least 1 second > * before taking any action that relies on power having been > * removed from the slot/adapter. > */ > msleep(1000); > > + /* ignore link or presence changes caused by power off */ > + atomic_and(~(PCI_EXP_SLTSTA_DLLSC | PCI_EXP_SLTSTA_PDC), > + &ctrl->pending_events); > } > > Would this work for you? Thank you for the review and for the proposed change! This discards exactly the event which caused the issue - I've just checked it on our hardware, and will resend it as a v2. Best regards, Serge > > Thanks, > > Lukas >
diff --git a/drivers/pci/hotplug/pciehp_ctrl.c b/drivers/pci/hotplug/pciehp_ctrl.c index 3f3df4c29f6e..941f77b71df4 100644 --- a/drivers/pci/hotplug/pciehp_ctrl.c +++ b/drivers/pci/hotplug/pciehp_ctrl.c @@ -251,6 +251,14 @@ void pciehp_handle_presence_or_link_change(struct controller *ctrl, u32 events) return; } + /* Handle the DLLSC from the slot which just has been turned off */ + if ((events & PCI_EXP_SLTSTA_DLLSC) && + !(events & PCI_EXP_SLTSTA_PDC) && + present && !link_active) { + mutex_unlock(&ctrl->state_lock); + return; + } + switch (ctrl->state) { case BLINKINGON_STATE: cancel_delayed_work(&ctrl->button_work);
During the safe removal procedure, a Data Link Layer State Changed event may occur after pciehp_power_off_slot(), and it is handled when the slot is already set to OFF_STATE. This results in re-enabling the device and makes it impossible to actually safely remove it. Add a check for a Presence Detect Changed bit to filter out this interrupt. It is still possible to re-enable the device if it remains in the slot after pressing the Attention Button by pressing it again. Signed-off-by: Sergey Miroshnichenko <s.miroshnichenko@yadro.com> Cc: Lukas Wunner <lukas@wunner.de> --- drivers/pci/hotplug/pciehp_ctrl.c | 8 ++++++++ 1 file changed, 8 insertions(+)