Messages in this thread Patch in this message | | | Date | Tue, 25 Apr 2017 19:28:38 +0200 | From | Sebastian Siewior <> | Subject | Re: [patch V2 00/24] cpu/hotplug: Convert get_online_cpus() to a percpu_rwsem |
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On 2017-04-25 17:10:37 [+0100], Mark Rutland wrote: > Hi, Hi,
> When we bring the secondary CPU online, we detect an erratum that wasn't > present on the boot CPU, and try to enable a static branch we use to > track the erratum. The call to static_branch_enable() blows up as above.
this (cpus_set_cap()) seems only to be used used in CPU up part.
> I see that we now have static_branch_disable_cpuslocked(), but we don't > have an equivalent for enable. I'm not sure what we should be doing > here.
We should introduce static_branch_enable_cpuslocked(). Does this work for you (after s/static_branch_enable/static_branch_enable_cpuslocked/ in cpus_set_cap()) ?:
From fe004351e4649da037d5165247e89ab976fe4a26 Mon Sep 17 00:00:00 2001 From: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Date: Tue, 25 Apr 2017 18:43:00 +0200 Subject: [PATCH] jump_label: Provide static_key_[enable|/slow_inc]_cpuslocked()
Provide static_key_[enable|slow_inc]_cpuslocked() variant that don't take cpu_hotplug_lock().
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> --- include/linux/jump_label.h | 7 +++++++ kernel/jump_label.c | 10 ++++++++++ 2 files changed, 17 insertions(+)
diff --git a/include/linux/jump_label.h b/include/linux/jump_label.h index d7b17d1ab875..c80d8b1279b5 100644 --- a/include/linux/jump_label.h +++ b/include/linux/jump_label.h @@ -164,6 +164,7 @@ extern void static_key_slow_dec_cpuslocked(struct static_key *key); extern void jump_label_apply_nops(struct module *mod); extern int static_key_count(struct static_key *key); extern void static_key_enable(struct static_key *key); +extern void static_key_enable_cpuslocked(struct static_key *key); extern void static_key_disable(struct static_key *key); extern void static_key_disable_cpuslocked(struct static_key *key); @@ -252,6 +253,11 @@ static inline void static_key_enable(struct static_key *key) static_key_slow_inc(key); } +static inline void static_key_enable_cpuslocked(struct static_key *key) +{ + static_key_enable(key); +} + static inline void static_key_disable(struct static_key *key) { int count = static_key_count(key); @@ -429,6 +435,7 @@ extern bool ____wrong_branch_error(void); */ #define static_branch_enable(x) static_key_enable(&(x)->key) +#define static_branch_enable_cpuslocked(x) static_key_enable_cpuslocked(&(x)->key) #define static_branch_disable(x) static_key_disable(&(x)->key) #define static_branch_disable_cpuslocked(x) static_key_disable_cpuslocked(&(x)->key) diff --git a/kernel/jump_label.c b/kernel/jump_label.c index d71124ee3b14..6343f4c7e27f 100644 --- a/kernel/jump_label.c +++ b/kernel/jump_label.c @@ -90,6 +90,16 @@ void static_key_enable(struct static_key *key) } EXPORT_SYMBOL_GPL(static_key_enable); +void static_key_enable_cpuslocked(struct static_key *key) +{ + int count = static_key_count(key); + + WARN_ON_ONCE(count < 0 || count > 1); + + if (!count) + static_key_slow_inc_cpuslocked(key); +} + void static_key_disable(struct static_key *key) { int count = static_key_count(key); -- 2.11.0 > Thanks, > Mark.
Sebastian
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