diff mbox series

[v6,02/11] cpu/hotplug: Move idle_thread_get() to <linux/smpboot.h>

Message ID 20230202215625.3248306-3-usama.arif@bytedance.com (mailing list archive)
State Superseded
Headers show
Series Parallel CPU bringup for x86_64 | expand

Commit Message

Usama Arif Feb. 2, 2023, 9:56 p.m. UTC 
From: David Woodhouse <dwmw@amazon.co.uk>

Instead of relying purely on the special-case wrapper in bringup_cpu()
to pass the idle thread to __cpu_up(), expose idle_thread_get() so that
the architecture code can obtain it directly when necessary.

This will be useful when the existing __cpu_up() is split into multiple
phases, only *one* of which will actually need the idle thread.

If the architecture code is to register its new pre-bringup states with
the cpuhp core, having a special-case wrapper to pass extra arguments is
non-trivial and it's easier just to let the arch register its function
pointer to be invoked with the standard API.

Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
---
 include/linux/smpboot.h | 7 +++++++
 kernel/smpboot.h        | 2 --
 2 files changed, 7 insertions(+), 2 deletions(-)

Comments

Thomas Gleixner Feb. 6, 2023, 11:33 p.m. UTC | #1 
On Thu, Feb 02 2023 at 21:56, Usama Arif wrote:
> If the architecture code is to register its new pre-bringup states with
> the cpuhp core, having a special-case wrapper to pass extra arguments is
> non-trivial and it's easier just to let the arch register its function
> pointer to be invoked with the standard API.
>
> Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

Same issue vs. the SOB chain.

Other than that:

Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Paul E. McKenney Feb. 7, 2023, 1:24 a.m. UTC | #2 
On Tue, Feb 07, 2023 at 12:33:03AM +0100, Thomas Gleixner wrote:
> On Thu, Feb 02 2023 at 21:56, Usama Arif wrote:
> > If the architecture code is to register its new pre-bringup states with
> > the cpuhp core, having a special-case wrapper to pass extra arguments is
> > non-trivial and it's easier just to let the arch register its function
> > pointer to be invoked with the standard API.
> >
> > Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
> > Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
> 
> Same issue vs. the SOB chain.
> 
> Other than that:
> 
> Reviewed-by: Thomas Gleixner <tglx@linutronix.de>

I pulled David's earlier version of this series into -rcu strictly
for testing purposes, so perhaps Usama pulled the series from my repo.
I don't have any record of doing anything more than test that series,
so dropping my SoB entirely makes the most sense here.

							Thanx, Paul
diff mbox series

Patch

diff --git a/include/linux/smpboot.h b/include/linux/smpboot.h
index 9d1bc65d226c..3862addcaa34 100644
--- a/include/linux/smpboot.h
+++ b/include/linux/smpboot.h
@@ -5,6 +5,13 @@ 
 #include <linux/types.h>
 
 struct task_struct;
+
+#ifdef CONFIG_GENERIC_SMP_IDLE_THREAD
+struct task_struct *idle_thread_get(unsigned int cpu);
+#else
+static inline struct task_struct *idle_thread_get(unsigned int cpu) { return NULL; }
+#endif
+
 /* Cookie handed to the thread_fn*/
 struct smpboot_thread_data;
 
diff --git a/kernel/smpboot.h b/kernel/smpboot.h
index 34dd3d7ba40b..60c609318ad6 100644
--- a/kernel/smpboot.h
+++ b/kernel/smpboot.h
@@ -5,11 +5,9 @@ 
 struct task_struct;
 
 #ifdef CONFIG_GENERIC_SMP_IDLE_THREAD
-struct task_struct *idle_thread_get(unsigned int cpu);
 void idle_thread_set_boot_cpu(void);
 void idle_threads_init(void);
 #else
-static inline struct task_struct *idle_thread_get(unsigned int cpu) { return NULL; }
 static inline void idle_thread_set_boot_cpu(void) { }
 static inline void idle_threads_init(void) { }
 #endif