No need for syscall slowpath if no CPU is full dynticks,
rather nop this in this case.
Signed-off-by: Frederic Weisbecker <fweis...@gmail.com>
Cc: Steven Rostedt <rost...@goodmis.org>
Cc: Paul E. McKenney <paul...@linux.vnet.ibm.com>
Cc: Ingo Molnar <mi...@kernel.org>
Cc: Thomas Gleixner <t...@linutronix.de>
Cc: Peter Zijlstra <pet...@infradead.org>
Cc: Borislav Petkov <b...@alien8.de>
Cc: Li Zhong <zh...@linux.vnet.ibm.com>
Cc: Mike Galbraith <efa...@gmx.de>
Cc: Kevin Hilman <khil...@linaro.org>
---
include/linux/context_tracking.h | 11 +++++++++--
kernel/context_tracking.c | 6 +++---
2 files changed, 12 insertions(+), 5 deletions(-)
diff --git a/include/linux/context_tracking.h b/include/linux/context_tracking.h
index 03a32b0..66a8397 100644
--- a/include/linux/context_tracking.h
+++ b/include/linux/context_tracking.h
@@ -40,6 +40,8 @@ extern void context_tracking_cpu_set(int cpu);
extern void context_tracking_user_enter(void);
extern void context_tracking_user_exit(void);
+extern void __context_tracking_task_switch(struct task_struct *prev,
+ struct task_struct *next);
static inline void user_enter(void)
{
@@ -74,8 +76,12 @@ static inline void exception_exit(enum ctx_state prev_ctx)
}
}
-extern void context_tracking_task_switch(struct task_struct *prev,
- struct task_struct *next);
+static inline void context_tracking_task_switch(struct task_struct *prev,
+ struct task_struct *next)
+{
+ if (static_key_false(&context_tracking_enabled))
+ __context_tracking_task_switch(prev, next);
+}
#else
static inline bool context_tracking_in_user(void) { return false; }
static inline void user_enter(void) { }
@@ -104,6 +110,7 @@ static inline void guest_exit(void)
else
current->flags &= ~PF_VCPU;
}
+
#else
static inline void guest_enter(void)
{
diff --git a/kernel/context_tracking.c b/kernel/context_tracking.c
index 5afa36b..ef21e4f 100644
--- a/kernel/context_tracking.c
+++ b/kernel/context_tracking.c
@@ -166,7 +166,7 @@ void context_tracking_user_exit(void)
}
/**
- * context_tracking_task_switch - context switch the syscall callbacks
+ * __context_tracking_task_switch - context switch the syscall callbacks
* @prev: the task that is being switched out
* @next: the task that is being switched in
*
@@ -178,8 +178,8 @@ void context_tracking_user_exit(void)
* migrate to some CPU that doesn't do the context tracking. As such the TIF
* flag may not be desired there.
*/
-void context_tracking_task_switch(struct task_struct *prev,
- struct task_struct *next)
+void __context_tracking_task_switch(struct task_struct *prev,
+ struct task_struct *next)
{
clear_tsk_thread_flag(prev, TIF_NOHZ);
set_tsk_thread_flag(next, TIF_NOHZ);
--
1.7.5.4
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