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| author | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2014-08-14 16:01:53 -0700 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2014-09-07 16:27:34 -0700 |
| commit | 1d082fd061884a587c490c4fc8a2056ce1e47624 (patch) | |
| tree | a8f715a674a036b1b7500a16ea11381d40659e42 /include/linux/init_task.h | |
| parent | 4ff475ed4cf61a7f56bbfbc424147189d0022b38 (diff) | |
| download | linux-1d082fd061884a587c490c4fc8a2056ce1e47624.tar.gz | |
rcu: Remove local_irq_disable() in rcu_preempt_note_context_switch()
The rcu_preempt_note_context_switch() function is on a scheduling fast
path, so it would be good to avoid disabling irqs. The reason that irqs
are disabled is to synchronize process-level and irq-handler access to
the task_struct ->rcu_read_unlock_special bitmask. This commit therefore
makes ->rcu_read_unlock_special instead be a union of bools with a short
allowing single-access checks in RCU's __rcu_read_unlock(). This results
in the process-level and irq-handler accesses being simple loads and
stores, so that irqs need no longer be disabled. This commit therefore
removes the irq disabling from rcu_preempt_note_context_switch().
Reported-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Diffstat (limited to 'include/linux/init_task.h')
| -rw-r--r-- | include/linux/init_task.h | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/include/linux/init_task.h b/include/linux/init_task.h index 03b274873b06f..77fc43f8fb72c 100644 --- a/include/linux/init_task.h +++ b/include/linux/init_task.h @@ -111,7 +111,7 @@ extern struct group_info init_groups; #ifdef CONFIG_PREEMPT_RCU #define INIT_TASK_RCU_PREEMPT(tsk) \ .rcu_read_lock_nesting = 0, \ - .rcu_read_unlock_special = 0, \ + .rcu_read_unlock_special.s = 0, \ .rcu_node_entry = LIST_HEAD_INIT(tsk.rcu_node_entry), \ INIT_TASK_RCU_TREE_PREEMPT() #else |