3.5-stable review patch. If anyone has any objections, please let me know.
------------------ From: Frederic Weisbecker <[email protected]> commit 4c94cada48f7c660eca582be6032427a5e367117 upstream. In the old times, the whole idle task was considered as an RCU quiescent state. But as RCU became more and more successful overtime, some RCU read side critical section have been added even in the code of some architectures idle tasks, for tracing for example. So nowadays, rcu_idle_enter() and rcu_idle_exit() must be called by the architecture to tell RCU about the part in the idle loop that doesn't make use of rcu read side critical sections, typically the part that puts the CPU in low power mode. This is necessary for RCU to find the quiescent states in idle in order to complete grace periods. Add this missing pair of calls in the Alpha's idle loop. Reported-by: Paul E. McKenney <[email protected]> Signed-off-by: Frederic Weisbecker <[email protected]> Tested-by: Michael Cree <[email protected]> Cc: Richard Henderson <[email protected]> Cc: Ivan Kokshaysky <[email protected]> Cc: Matt Turner <[email protected]> Cc: alpha <[email protected]> Cc: Paul E. McKenney <[email protected]> Reviewed-by: Josh Triplett <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- arch/alpha/kernel/process.c | 3 +++ 1 file changed, 3 insertions(+) --- a/arch/alpha/kernel/process.c +++ b/arch/alpha/kernel/process.c @@ -28,6 +28,7 @@ #include <linux/tty.h> #include <linux/console.h> #include <linux/slab.h> +#include <linux/rcupdate.h> #include <asm/reg.h> #include <asm/uaccess.h> @@ -54,8 +55,10 @@ cpu_idle(void) /* FIXME -- EV6 and LCA45 know how to power down the CPU. */ + rcu_idle_enter(); while (!need_resched()) cpu_relax(); + rcu_idle_exit(); schedule(); } } -- 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/
