On Mon, 2012-07-16 at 08:07 +0000, Thomas Gleixner wrote:
I know you are on vacation (hope you are enjoying yourself ;-)
> ---
> include/linux/sched.h | 7 ++
> kernel/cpu.c | 236 +++++++++++++++++++++++++++++++++++++++++--------
> kernel/sched/core.c | 82 +++++++++++++++++-
> 3 files changed, 285 insertions(+), 40 deletions(-)
>
> diff --git a/include/linux/sched.h b/include/linux/sched.h
> index 7fc8321..777f7bb 100644
> --- a/include/linux/sched.h
> +++ b/include/linux/sched.h
> @@ -1973,6 +1973,10 @@ extern void do_set_cpus_allowed(struct task_struct *p,
>
> extern int set_cpus_allowed_ptr(struct task_struct *p,
> const struct cpumask *new_mask);
> +int migrate_me(void);
> +void tell_sched_cpu_down_begin(int cpu);
> +void tell_sched_cpu_down_done(int cpu);
> +
> #else
> static inline void do_set_cpus_allowed(struct task_struct *p,
> const struct cpumask *new_mask)
> @@ -1985,6 +1989,9 @@ static inline int set_cpus_allowed_ptr(struct task_struct *p,
> return -EINVAL;
> return 0;
> }
> +static inline int migrate_me(void) { return 0; }
> +static inline void tell_sched_cpu_down_begin(int cpu) { }
> +static inline void tell_sched_cpu_down_done(int cpu) { }
> #endif
>
> #ifndef CONFIG_CPUMASK_OFFSTACK
> diff --git a/kernel/cpu.c b/kernel/cpu.c
> index d79d33a..c5b3273 100644
> --- a/kernel/cpu.c
> +++ b/kernel/cpu.c
> @@ -46,12 +46,7 @@ static int cpu_hotplug_disabled;
>
> static struct {
> struct task_struct *active_writer;
> -#ifdef CONFIG_PREEMPT_RT_FULL
> - /* Makes the lock keep the task's state */
> - spinlock_t lock;
> -#else
> struct mutex lock; /* Synchronizes accesses to refcount, */
> -#endif
> /*
> * Also blocks the new readers during
> * an ongoing cpu hotplug operation.
> @@ -67,20 +62,42 @@ static struct {
As I was backporting this to 3.0-rt, I noticed that the following is
needed too:
diff --git a/kernel/cpu.c b/kernel/cpu.c
index c5b3273..3e722c0 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -54,11 +54,7 @@ static struct {
int refcount;
} cpu_hotplug = {
.active_writer = NULL,
-#ifdef CONFIG_PREEMPT_RT_FULL
- .lock = __SPIN_LOCK_UNLOCKED(cpu_hotplug.lock),
-#else
.lock = __MUTEX_INITIALIZER(cpu_hotplug.lock),
-#endif
.refcount = 0,
};
As this goes with part of the applied patch above.
I'll add this on top, if no one objects.
-- Steve
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