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| author | Rafael J. Wysocki <rjw@sisk.pl> | 2009-05-24 21:15:07 +0200 |
|---|---|---|
| committer | Rafael J. Wysocki <rjw@sisk.pl> | 2009-05-24 21:15:07 +0200 |
| commit | 32bdfac5462d777f35b00838893c4f87baf23efe (patch) | |
| tree | 92e4ef3af7b68007e8004eaca978865a29e543b0 /kernel/kexec.c | |
| parent | Linux 2.6.30-rc7 (diff) | |
| download | linux-32bdfac5462d777f35b00838893c4f87baf23efe.tar.xz linux-32bdfac5462d777f35b00838893c4f87baf23efe.zip | |
PM: Do not hold dpm_list_mtx while disabling/enabling nonboot CPUs
We shouldn't hold dpm_list_mtx while executing
[disable|enable]_nonboot_cpus(), because theoretically this may lead
to a deadlock as shown by the following example (provided by Johannes
Berg):
CPU 3 CPU 2 CPU 1
suspend/hibernate
something:
rtnl_lock() device_pm_lock()
-> mutex_lock(&dpm_list_mtx)
mutex_lock(&dpm_list_mtx)
linkwatch_work
-> rtnl_lock()
disable_nonboot_cpus()
-> flush CPU 3 workqueue
Fortunately, device drivers are supposed to stop any activities that
might lead to the registration of new device objects way before
disable_nonboot_cpus() is called, so it shouldn't be necessary to
hold dpm_list_mtx over the entire late part of device suspend and
early part of device resume.
Thus, during the late suspend and the early resume of devices acquire
dpm_list_mtx only when dpm_list is going to be traversed and release
it right after that.
This patch is reported to fix the regressions tracked as
http://bugzilla.kernel.org/show_bug.cgi?id=13245.
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Reported-by: Miles Lane <miles.lane@gmail.com>
Tested-by: Ming Lei <tom.leiming@gmail.com>
Diffstat (limited to 'kernel/kexec.c')
| -rw-r--r-- | kernel/kexec.c | 2 |
1 files changed, 0 insertions, 2 deletions
diff --git a/kernel/kexec.c b/kernel/kexec.c index 5a758c6e4950..e4983770913b 100644 --- a/kernel/kexec.c +++ b/kernel/kexec.c @@ -1451,7 +1451,6 @@ int kernel_kexec(void) error = device_suspend(PMSG_FREEZE); if (error) goto Resume_console; - device_pm_lock(); /* At this point, device_suspend() has been called, * but *not* device_power_down(). We *must* * device_power_down() now. Otherwise, drivers for @@ -1489,7 +1488,6 @@ int kernel_kexec(void) enable_nonboot_cpus(); device_power_up(PMSG_RESTORE); Resume_devices: - device_pm_unlock(); device_resume(PMSG_RESTORE); Resume_console: resume_console(); |