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authorFrederic Weisbecker <fweisbec@gmail.com>2011-10-08 16:01:00 +0200
committerPaul E. McKenney <paulmck@linux.vnet.ibm.com>2011-12-11 10:31:36 -0800
commit2bbb6817c0ac1b5f2a68d720f364f98eeb1ac4fd (patch)
tree05bb5ba54671a8eaeca4fe4406a75e820317e473 /arch/x86/kernel
parent280f06774afedf849f0b34248ed6aff57d0f6908 (diff)
nohz: Allow rcu extended quiescent state handling seperately from tick stop
It is assumed that rcu won't be used once we switch to tickless mode and until we restart the tick. However this is not always true, as in x86-64 where we dereference the idle notifiers after the tick is stopped. To prepare for fixing this, add two new APIs: tick_nohz_idle_enter_norcu() and tick_nohz_idle_exit_norcu(). If no use of RCU is made in the idle loop between tick_nohz_enter_idle() and tick_nohz_exit_idle() calls, the arch must instead call the new *_norcu() version such that the arch doesn't need to call rcu_idle_enter() and rcu_idle_exit(). Otherwise the arch must call tick_nohz_enter_idle() and tick_nohz_exit_idle() and also call explicitly: - rcu_idle_enter() after its last use of RCU before the CPU is put to sleep. - rcu_idle_exit() before the first use of RCU after the CPU is woken up. Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Mike Frysinger <vapier@gentoo.org> Cc: Guan Xuetao <gxt@mprc.pku.edu.cn> Cc: David Miller <davem@davemloft.net> Cc: Chris Metcalf <cmetcalf@tilera.com> Cc: Hans-Christian Egtvedt <hans-christian.egtvedt@atmel.com> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Russell King <linux@arm.linux.org.uk> Cc: Paul Mackerras <paulus@samba.org> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Paul Mundt <lethal@linux-sh.org> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Diffstat (limited to 'arch/x86/kernel')
-rw-r--r--arch/x86/kernel/process_32.c4
-rw-r--r--arch/x86/kernel/process_64.c4
2 files changed, 4 insertions, 4 deletions
diff --git a/arch/x86/kernel/process_32.c b/arch/x86/kernel/process_32.c
index 6d9d4d52cac5..f94da3920c36 100644
--- a/arch/x86/kernel/process_32.c
+++ b/arch/x86/kernel/process_32.c
@@ -99,7 +99,7 @@ void cpu_idle(void)
/* endless idle loop with no priority at all */
while (1) {
- tick_nohz_idle_enter();
+ tick_nohz_idle_enter_norcu();
while (!need_resched()) {
check_pgt_cache();
@@ -116,7 +116,7 @@ void cpu_idle(void)
pm_idle();
start_critical_timings();
}
- tick_nohz_idle_exit();
+ tick_nohz_idle_exit_norcu();
preempt_enable_no_resched();
schedule();
preempt_disable();
diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
index b069e9d7875f..18e8cf3581f6 100644
--- a/arch/x86/kernel/process_64.c
+++ b/arch/x86/kernel/process_64.c
@@ -122,7 +122,7 @@ void cpu_idle(void)
/* endless idle loop with no priority at all */
while (1) {
- tick_nohz_idle_enter();
+ tick_nohz_idle_enter_norcu();
while (!need_resched()) {
rmb();
@@ -149,7 +149,7 @@ void cpu_idle(void)
__exit_idle();
}
- tick_nohz_idle_exit();
+ tick_nohz_idle_exit_norcu();
preempt_enable_no_resched();
schedule();
preempt_disable();

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