| From | Greg Kroah-Hartman <> | Subject | [ 104/133] frv: Add missing RCU idle APIs on idle loop | Date | Thu, 11 Oct 2012 07:52:10 +0900 |
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3.5-stable review patch. If anyone has any objections, please let me know.
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From: Frederic Weisbecker <fweisbec@gmail.com>
commit 41d8fe5bb3cf91ce2716ac8f43e4b40d802a99c8 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 Frv's idle loop.
Reported-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: David Howells <dhowells@redhat.com> Acked-by: David Howells <dhowells@redhat.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
--- arch/frv/kernel/process.c | 3 +++ 1 file changed, 3 insertions(+)
--- a/arch/frv/kernel/process.c +++ b/arch/frv/kernel/process.c @@ -25,6 +25,7 @@ #include <linux/reboot.h> #include <linux/interrupt.h> #include <linux/pagemap.h> +#include <linux/rcupdate.h> #include <asm/asm-offsets.h> #include <asm/uaccess.h> @@ -69,12 +70,14 @@ void cpu_idle(void) { /* endless idle loop with no priority at all */ while (1) { + rcu_idle_enter(); while (!need_resched()) { check_pgt_cache(); if (!frv_dma_inprogress && idle) idle(); } + rcu_idle_exit(); schedule_preempt_disabled(); }
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