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| author | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2015-09-01 00:42:57 -0700 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2015-10-06 11:15:43 -0700 |
| commit | 49f5903b473c5f63f3b57856d1bd4593db0a2eef (patch) | |
| tree | 99ac386a68b59fea8b9e26ce38d3d05df90da20e | |
| parent | 7f21aeef722d598ba350d1834f6e4134c7b5e8de (diff) | |
| download | linux-49f5903b473c5f63f3b57856d1bd4593db0a2eef.tar.bz2 | |
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>
| -rw-r--r-- | include/linux/srcu.h | 5 | ||||
| -rw-r--r-- | kernel/exit.c | 2 | ||||
| -rw-r--r-- | kernel/rcu/srcu.c | 2 |
3 files changed, 6 insertions, 3 deletions
diff --git a/include/linux/srcu.h b/include/linux/srcu.h index bdeb4567b71e..f5f80c5643ac 100644 --- a/include/linux/srcu.h +++ b/include/linux/srcu.h @@ -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; } diff --git a/kernel/exit.c b/kernel/exit.c index ea95ee1b5ef7..0e93b63bbc59 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -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 diff --git a/kernel/rcu/srcu.c b/kernel/rcu/srcu.c index 9e6122540d28..a63a1ea5a41b 100644 --- a/kernel/rcu/srcu.c +++ b/kernel/rcu/srcu.c @@ -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); |