* [PATCH] PCI: pciehp: Fix re-enabling the slot marked for safe removal
@ 2019-03-01 16:12 Sergey Miroshnichenko
2019-03-05 11:01 ` Lukas Wunner
0 siblings, 1 reply; 3+ messages in thread
From: Sergey Miroshnichenko @ 2019-03-01 16:12 UTC (permalink / raw)
To: linux-pci; +Cc: linux, Sergey Miroshnichenko, Lukas Wunner
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);
--
2.20.1
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] PCI: pciehp: Fix re-enabling the slot marked for safe removal
2019-03-01 16:12 [PATCH] PCI: pciehp: Fix re-enabling the slot marked for safe removal Sergey Miroshnichenko
@ 2019-03-05 11:01 ` Lukas Wunner
2019-03-12 12:03 ` Sergey Miroshnichenko
0 siblings, 1 reply; 3+ messages in thread
From: Lukas Wunner @ 2019-03-05 11:01 UTC (permalink / raw)
To: Sergey Miroshnichenko; +Cc: linux-pci, linux
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
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] PCI: pciehp: Fix re-enabling the slot marked for safe removal
2019-03-05 11:01 ` Lukas Wunner
@ 2019-03-12 12:03 ` Sergey Miroshnichenko
0 siblings, 0 replies; 3+ messages in thread
From: Sergey Miroshnichenko @ 2019-03-12 12:03 UTC (permalink / raw)
To: Lukas Wunner; +Cc: linux-pci, linux
[-- Attachment #1.1: Type: text/plain, Size: 2365 bytes --]
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
>
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^ permalink raw reply [flat|nested] 3+ messages in thread
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2019-03-01 16:12 [PATCH] PCI: pciehp: Fix re-enabling the slot marked for safe removal Sergey Miroshnichenko
2019-03-05 11:01 ` Lukas Wunner
2019-03-12 12:03 ` Sergey Miroshnichenko
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