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authorFrederic Weisbecker <fweisbec@gmail.com>2012-12-16 20:00:34 +0100
committerFrederic Weisbecker <fweisbec@gmail.com>2013-01-27 20:35:47 +0100
commit6a61671bb2f3a1bd12cd17b8fca811a624782632 (patch)
tree0afc2915fb7e517472710a49a524510322dd5baa /kernel/context_tracking.c
parentc11f11fcbdb5be790c565aed46411486a7586afc (diff)
downloadlinux-sh-6a61671bb2f3a1bd12cd17b8fca811a624782632.tar.gz
cputime: Safely read cputime of full dynticks CPUs
While remotely reading the cputime of a task running in a full dynticks CPU, the values stored in utime/stime fields of struct task_struct may be stale. Its values may be those of the last kernel <-> user transition time snapshot and we need to add the tickless time spent since this snapshot. To fix this, flush the cputime of the dynticks CPUs on kernel <-> user transition and record the time / context where we did this. Then on top of this snapshot and the current time, perform the fixup on the reader side from task_times() accessors. Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Ingo Molnar <mingo@kernel.org> Cc: Li Zhong <zhong@linux.vnet.ibm.com> Cc: Namhyung Kim <namhyung.kim@lge.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Paul Gortmaker <paul.gortmaker@windriver.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de> [fixed kvm module related build errors] Signed-off-by: Sedat Dilek <sedat.dilek@gmail.com>
Diffstat (limited to 'kernel/context_tracking.c')
-rw-r--r--kernel/context_tracking.c21
1 files changed, 20 insertions, 1 deletions
diff --git a/kernel/context_tracking.c b/kernel/context_tracking.c
index 9002e92e6372..74f68f4dc6c2 100644
--- a/kernel/context_tracking.c
+++ b/kernel/context_tracking.c
@@ -1,8 +1,9 @@
#include <linux/context_tracking.h>
+#include <linux/kvm_host.h>
#include <linux/rcupdate.h>
#include <linux/sched.h>
#include <linux/hardirq.h>
-
+#include <linux/export.h>
DEFINE_PER_CPU(struct context_tracking, context_tracking) = {
#ifdef CONFIG_CONTEXT_TRACKING_FORCE
@@ -61,6 +62,24 @@ void user_exit(void)
local_irq_restore(flags);
}
+void guest_enter(void)
+{
+ if (vtime_accounting_enabled())
+ vtime_guest_enter(current);
+ else
+ __guest_enter();
+}
+EXPORT_SYMBOL_GPL(guest_enter);
+
+void guest_exit(void)
+{
+ if (vtime_accounting_enabled())
+ vtime_guest_exit(current);
+ else
+ __guest_exit();
+}
+EXPORT_SYMBOL_GPL(guest_exit);
+
void context_tracking_task_switch(struct task_struct *prev,
struct task_struct *next)
{