* [BUG] usb: xhci: Two possible sleep-in-atomic-context bugs
@ 2018-06-20 3:12 Jia-Ju Bai
2018-06-20 3:28 ` Peter Chen
0 siblings, 1 reply; 3+ messages in thread
From: Jia-Ju Bai @ 2018-06-20 3:12 UTC (permalink / raw)
To: mathias.nyman, gregkh; +Cc: linux-usb, Linux Kernel Mailing List
The driver may sleep with holding a spinlock.
The function call paths (from bottom to top) in Linux-4.16.7 are:
[FUNC] schedule
drivers/base/power/runtime.c, 741: schedule in rpm_resume
drivers/base/power/runtime.c, 1322: rpm_resume in pm_runtime_forbid
drivers/usb/host/xhci-hub.c, 647: pm_runtime_forbid in xhci_enter_test_mode
drivers/usb/host/xhci-hub.c, 632: _raw_spin_lock_irqsave in
xhci_enter_test_mode
[FUNC] schedule
drivers/base/power/runtime.c, 570: schedule in rpm_suspend
drivers/base/power/runtime.c, 434: rpm_suspend in rpm_idle
drivers/base/power/runtime.c, 1343: rpm_idle in pm_runtime_allow
drivers/usb/host/xhci-hub.c, 670: pm_runtime_allow in xhci_exit_test_mode
drivers/usb/host/xhci-hub.c, 1387: xhci_exit_test_mode in xhci_hub_control
drivers/usb/host/xhci-hub.c, 1038: _raw_spin_lock_irqsave in
xhci_hub_control
These bugs are found by my static analysis tool (DSAC-2) and checked by my
code review.
I do not know how to correctly fix these bugs, so I just report them.
Best wishes,
Jia-Ju Bai
^ permalink raw reply [flat|nested] 3+ messages in thread
* RE: [BUG] usb: xhci: Two possible sleep-in-atomic-context bugs
2018-06-20 3:12 [BUG] usb: xhci: Two possible sleep-in-atomic-context bugs Jia-Ju Bai
@ 2018-06-20 3:28 ` Peter Chen
2018-06-20 9:15 ` Mathias Nyman
0 siblings, 1 reply; 3+ messages in thread
From: Peter Chen @ 2018-06-20 3:28 UTC (permalink / raw)
To: Jia-Ju Bai, mathias.nyman, gregkh; +Cc: linux-usb, Linux Kernel Mailing List
>
> The driver may sleep with holding a spinlock.
> The function call paths (from bottom to top) in Linux-4.16.7 are:
>
> [FUNC] schedule
> drivers/base/power/runtime.c, 741: schedule in rpm_resume
> drivers/base/power/runtime.c, 1322: rpm_resume in pm_runtime_forbid
> drivers/usb/host/xhci-hub.c, 647: pm_runtime_forbid in xhci_enter_test_mode
> drivers/usb/host/xhci-hub.c, 632: _raw_spin_lock_irqsave in xhci_enter_test_mode
>
> [FUNC] schedule
> drivers/base/power/runtime.c, 570: schedule in rpm_suspend
> drivers/base/power/runtime.c, 434: rpm_suspend in rpm_idle
> drivers/base/power/runtime.c, 1343: rpm_idle in pm_runtime_allow
> drivers/usb/host/xhci-hub.c, 670: pm_runtime_allow in xhci_exit_test_mode
> drivers/usb/host/xhci-hub.c, 1387: xhci_exit_test_mode in xhci_hub_control
> drivers/usb/host/xhci-hub.c, 1038: _raw_spin_lock_irqsave in xhci_hub_control
>
> These bugs are found by my static analysis tool (DSAC-2) and checked by my code
> review.
>
I don't think runtime PM API is needed at xhci_hub_control since the controller should
be always active, Mathias, do you agree I delete pm_runtime_forbid and pm_runtime_allow
to fix this issue?
Peter
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [BUG] usb: xhci: Two possible sleep-in-atomic-context bugs
2018-06-20 3:28 ` Peter Chen
@ 2018-06-20 9:15 ` Mathias Nyman
0 siblings, 0 replies; 3+ messages in thread
From: Mathias Nyman @ 2018-06-20 9:15 UTC (permalink / raw)
To: Peter Chen, Jia-Ju Bai, mathias.nyman, gregkh
Cc: linux-usb, Linux Kernel Mailing List
On 20.06.2018 06:28, Peter Chen wrote:
>
>>
>> The driver may sleep with holding a spinlock.
>> The function call paths (from bottom to top) in Linux-4.16.7 are:
>>
>> [FUNC] schedule
>> drivers/base/power/runtime.c, 741: schedule in rpm_resume
>> drivers/base/power/runtime.c, 1322: rpm_resume in pm_runtime_forbid
>> drivers/usb/host/xhci-hub.c, 647: pm_runtime_forbid in xhci_enter_test_mode
>> drivers/usb/host/xhci-hub.c, 632: _raw_spin_lock_irqsave in xhci_enter_test_mode
>>
>> [FUNC] schedule
>> drivers/base/power/runtime.c, 570: schedule in rpm_suspend
>> drivers/base/power/runtime.c, 434: rpm_suspend in rpm_idle
>> drivers/base/power/runtime.c, 1343: rpm_idle in pm_runtime_allow
>> drivers/usb/host/xhci-hub.c, 670: pm_runtime_allow in xhci_exit_test_mode
>> drivers/usb/host/xhci-hub.c, 1387: xhci_exit_test_mode in xhci_hub_control
>> drivers/usb/host/xhci-hub.c, 1038: _raw_spin_lock_irqsave in xhci_hub_control
>>
>> These bugs are found by my static analysis tool (DSAC-2) and checked by my code
>> review.
>>
>
> I don't think runtime PM API is needed at xhci_hub_control since the controller should
> be always active, Mathias, do you agree I delete pm_runtime_forbid and pm_runtime_allow
> to fix this issue?
>
The USB2 test mode is a bit special, it will disable all connected devices, and halt the host.
Port should stay in test mode until feature is cleared or host reset.
There is a risk runtime suspend will try to suspend the host as no devices seem preset.
But I think pm_runtime_get_noresume() and pm_runtime_put_noidle() could be used instad,
those should be safe.
-Mathias
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2018-06-20 9:12 UTC | newest]
Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2018-06-20 3:12 [BUG] usb: xhci: Two possible sleep-in-atomic-context bugs Jia-Ju Bai
2018-06-20 3:28 ` Peter Chen
2018-06-20 9:15 ` Mathias Nyman
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).