rcu: Move preemption disabling out of __srcu_read_lock()
Currently, __srcu_read_lock() cannot be invoked from restricted
environments because it contains calls to preempt_disable() and
preempt_enable(), both of which can invoke lockdep, which is a bad
idea in some restricted execution modes. This commit therefore moves
the preempt_disable() and preempt_enable() from __srcu_read_lock()
to srcu_read_lock(). It also inserts the preempt_disable() and
preempt_enable() around the call to __srcu_read_lock() in do_exit().
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
diff --git a/kernel/exit.c b/kernel/exit.c
index ea95ee1..0e93b63 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -761,7 +761,9 @@
*/
flush_ptrace_hw_breakpoint(tsk);
+ TASKS_RCU(preempt_disable());
TASKS_RCU(tasks_rcu_i = __srcu_read_lock(&tasks_rcu_exit_srcu));
+ TASKS_RCU(preempt_enable());
exit_notify(tsk, group_dead);
proc_exit_connector(tsk);
#ifdef CONFIG_NUMA