Commit 49f5903b authored by Paul E. McKenney's avatar Paul E. McKenney

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: default avatarPaul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: default avatarJosh Triplett <josh@joshtriplett.org>
parent 7f21aeef
......@@ -215,8 +215,11 @@ static inline int srcu_read_lock_held(struct srcu_struct *sp)
*/
static inline int srcu_read_lock(struct srcu_struct *sp) __acquires(sp)
{
int retval = __srcu_read_lock(sp);
int retval;
preempt_disable();
retval = __srcu_read_lock(sp);
preempt_enable();
rcu_lock_acquire(&(sp)->dep_map);
return retval;
}
......
......@@ -761,7 +761,9 @@ void do_exit(long code)
*/
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
......
......@@ -298,11 +298,9 @@ int __srcu_read_lock(struct srcu_struct *sp)
int idx;
idx = READ_ONCE(sp->completed) & 0x1;
preempt_disable();
__this_cpu_inc(sp->per_cpu_ref->c[idx]);
smp_mb(); /* B */ /* Avoid leaking the critical section. */
__this_cpu_inc(sp->per_cpu_ref->seq[idx]);
preempt_enable();
return idx;
}
EXPORT_SYMBOL_GPL(__srcu_read_lock);
......
Markdown is supported
0% or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment