From: "Paul E. McKenney" <[email protected]> There is a need to use RCU from interrupt context, but either before rcu_irq_enter() is called or after rcu_irq_exit() is called. If the interrupt occurs from idle, then lockdep-RCU will complain about such uses, as they appear to be illegal uses of RCU from the idle loop. In other environments, RCU_NONIDLE() could be used to properly protect the use of RCU, but RCU_NONIDLE() currently cannot be invoked except from process context.
This commit therefore modifies RCU_NONIDLE() to permit its use more globally. Reported-by: Steven Rostedt <[email protected]> Signed-off-by: Paul E. McKenney <[email protected]> Signed-off-by: Paul E. McKenney <[email protected]> --- include/linux/rcupdate.h | 6 ++---- kernel/rcutiny.c | 2 ++ kernel/rcutree.c | 2 ++ 3 files changed, 6 insertions(+), 4 deletions(-) diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h index 115ead2..0fbbd52 100644 --- a/include/linux/rcupdate.h +++ b/include/linux/rcupdate.h @@ -210,14 +210,12 @@ extern void exit_rcu(void); * to nest RCU_NONIDLE() wrappers, but the nesting level is currently * quite limited. If deeper nesting is required, it will be necessary * to adjust DYNTICK_TASK_NESTING_VALUE accordingly. - * - * This macro may be used from process-level code only. */ #define RCU_NONIDLE(a) \ do { \ - rcu_idle_exit(); \ + rcu_irq_enter(); \ do { a; } while (0); \ - rcu_idle_enter(); \ + rcu_irq_exit(); \ } while (0) /* diff --git a/kernel/rcutiny.c b/kernel/rcutiny.c index e4163c5..2e073a2 100644 --- a/kernel/rcutiny.c +++ b/kernel/rcutiny.c @@ -115,6 +115,7 @@ void rcu_irq_exit(void) rcu_idle_enter_common(newval); local_irq_restore(flags); } +EXPORT_SYMBOL_GPL(rcu_irq_exit); /* Common code for rcu_idle_exit() and rcu_irq_enter(), see kernel/rcutree.c. */ static void rcu_idle_exit_common(long long oldval) @@ -172,6 +173,7 @@ void rcu_irq_enter(void) rcu_idle_exit_common(oldval); local_irq_restore(flags); } +EXPORT_SYMBOL_GPL(rcu_irq_enter); #ifdef CONFIG_DEBUG_LOCK_ALLOC diff --git a/kernel/rcutree.c b/kernel/rcutree.c index f280e54..96b8aff 100644 --- a/kernel/rcutree.c +++ b/kernel/rcutree.c @@ -447,6 +447,7 @@ void rcu_irq_exit(void) rcu_idle_enter_common(rdtp, oldval); local_irq_restore(flags); } +EXPORT_SYMBOL_GPL(rcu_irq_exit); /* * rcu_idle_exit_common - inform RCU that current CPU is moving away from idle @@ -542,6 +543,7 @@ void rcu_irq_enter(void) rcu_idle_exit_common(rdtp, oldval); local_irq_restore(flags); } +EXPORT_SYMBOL_GPL(rcu_irq_enter); /** * rcu_nmi_enter - inform RCU of entry to NMI context -- 1.7.8 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
