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authorPaul E. McKenney <paulmck@linux.vnet.ibm.com>2014-10-22 10:00:05 -0700
committerPaul E. McKenney <paulmck@linux.vnet.ibm.com>2014-10-23 07:51:17 -0700
commitb2c4623dcd07af4b8ae3b56ae5f879e281c7b4f8 (patch)
tree8a0aaf80f950011fafb6743d42457a22412ae6dd /kernel/rcu/tree.c
parentf114040e3ea6e07372334ade75d1ee0775c355e1 (diff)
rcu: More on deadlock between CPU hotplug and expedited grace periods
Commit dd56af42bd82 (rcu: Eliminate deadlock between CPU hotplug and expedited grace periods) was incomplete. Although it did eliminate deadlocks involving synchronize_sched_expedited()'s acquisition of cpu_hotplug.lock via get_online_cpus(), it did nothing about the similar deadlock involving acquisition of this same lock via put_online_cpus(). This deadlock became apparent with testing involving hibernation. This commit therefore changes put_online_cpus() acquisition of this lock to be conditional, and increments a new cpu_hotplug.puts_pending field in case of acquisition failure. Then cpu_hotplug_begin() checks for this new field being non-zero, and applies any changes to cpu_hotplug.refcount. Reported-by: Jiri Kosina <jkosina@suse.cz> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Tested-by: Jiri Kosina <jkosina@suse.cz> Tested-by: Borislav Petkov <bp@suse.de>
Diffstat (limited to 'kernel/rcu/tree.c')
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