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author | Rafael J. Wysocki <rjw@sisk.pl> | 2009-05-24 21:15:07 +0200 |
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committer | Rafael J. Wysocki <rjw@sisk.pl> | 2009-05-24 21:15:07 +0200 |
commit | 32bdfac5462d777f35b00838893c4f87baf23efe (patch) | |
tree | 92e4ef3af7b68007e8004eaca978865a29e543b0 /kernel/fork.c | |
parent | 59a3759d0fe8d969888c741bb33f4946e4d3750d (diff) |
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/fork.c')
0 files changed, 0 insertions, 0 deletions