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SubjectRe: [PATCH net-next v3 3/9] static_key: WARN on usage before jump_label_init was called
On Thu, 17 Oct 2013 07:31:57 +0200
Hannes Frederic Sowa <hannes@stressinduktion.org> wrote:

> Based on a patch from Andi Kleen.

I'm fine with the patch, but the change log needs a lot more work.
Like, why is this needed? I know, but does anyone else?

-- Steve



>
> Cc: Steven Rostedt <rostedt@goodmis.org>
> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
> Cc: Andi Kleen <andi@firstfloor.org>
> Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
> ---
> include/linux/jump_label.h | 10 ++++++++++
> include/linux/jump_label_ratelimit.h | 2 ++
> init/main.c | 7 +++++++
> kernel/jump_label.c | 5 +++++
> 4 files changed, 24 insertions(+)
>
> diff --git a/include/linux/jump_label.h b/include/linux/jump_label.h
> index a507907..e96be72 100644
> --- a/include/linux/jump_label.h
> +++ b/include/linux/jump_label.h
> @@ -48,6 +48,13 @@
>
> #include <linux/types.h>
> #include <linux/compiler.h>
> +#include <linux/bug.h>
> +
> +extern bool static_key_initialized;
> +
> +#define STATIC_KEY_CHECK_USE() WARN(!static_key_initialized, \
> + "%s used before call to jump_label_init", \
> + __func__)
>
> #if defined(CC_HAVE_ASM_GOTO) && defined(CONFIG_JUMP_LABEL)
>
> @@ -128,6 +135,7 @@ struct static_key {
>
> static __always_inline void jump_label_init(void)
> {
> + static_key_initialized = true;
> }
>
> static __always_inline bool static_key_false(struct static_key *key)
> @@ -146,11 +154,13 @@ static __always_inline bool static_key_true(struct static_key *key)
>
> static inline void static_key_slow_inc(struct static_key *key)
> {
> + STATIC_KEY_CHECK_USE();
> atomic_inc(&key->enabled);
> }
>
> static inline void static_key_slow_dec(struct static_key *key)
> {
> + STATIC_KEY_CHECK_USE();
> atomic_dec(&key->enabled);
> }
>
> diff --git a/include/linux/jump_label_ratelimit.h b/include/linux/jump_label_ratelimit.h
> index 1137883..089f70f 100644
> --- a/include/linux/jump_label_ratelimit.h
> +++ b/include/linux/jump_label_ratelimit.h
> @@ -23,12 +23,14 @@ struct static_key_deferred {
> };
> static inline void static_key_slow_dec_deferred(struct static_key_deferred *key)
> {
> + STATIC_KEY_CHECK_USE();
> static_key_slow_dec(&key->key);
> }
> static inline void
> jump_label_rate_limit(struct static_key_deferred *key,
> unsigned long rl)
> {
> + STATIC_KEY_CHECK_USE();
> }
> #endif /* HAVE_JUMP_LABEL */
> #endif /* _LINUX_JUMP_LABEL_RATELIMIT_H */
> diff --git a/init/main.c b/init/main.c
> index af310af..27bbec1a 100644
> --- a/init/main.c
> +++ b/init/main.c
> @@ -136,6 +136,13 @@ static char *execute_command;
> static char *ramdisk_execute_command;
>
> /*
> + * Used to generate warnings if static_key manipulation functions are used
> + * before jump_label_init is called.
> + */
> +bool static_key_initialized __read_mostly = false;
> +EXPORT_SYMBOL_GPL(static_key_initialized);
> +
> +/*
> * If set, this is an indication to the drivers that reset the underlying
> * device before going ahead with the initialization otherwise driver might
> * rely on the BIOS and skip the reset operation.
> diff --git a/kernel/jump_label.c b/kernel/jump_label.c
> index 297a924..9019f15 100644
> --- a/kernel/jump_label.c
> +++ b/kernel/jump_label.c
> @@ -58,6 +58,7 @@ static void jump_label_update(struct static_key *key, int enable);
>
> void static_key_slow_inc(struct static_key *key)
> {
> + STATIC_KEY_CHECK_USE();
> if (atomic_inc_not_zero(&key->enabled))
> return;
>
> @@ -103,12 +104,14 @@ static void jump_label_update_timeout(struct work_struct *work)
>
> void static_key_slow_dec(struct static_key *key)
> {
> + STATIC_KEY_CHECK_USE();
> __static_key_slow_dec(key, 0, NULL);
> }
> EXPORT_SYMBOL_GPL(static_key_slow_dec);
>
> void static_key_slow_dec_deferred(struct static_key_deferred *key)
> {
> + STATIC_KEY_CHECK_USE();
> __static_key_slow_dec(&key->key, key->timeout, &key->work);
> }
> EXPORT_SYMBOL_GPL(static_key_slow_dec_deferred);
> @@ -116,6 +119,7 @@ EXPORT_SYMBOL_GPL(static_key_slow_dec_deferred);
> void jump_label_rate_limit(struct static_key_deferred *key,
> unsigned long rl)
> {
> + STATIC_KEY_CHECK_USE();
> key->timeout = rl;
> INIT_DELAYED_WORK(&key->work, jump_label_update_timeout);
> }
> @@ -212,6 +216,7 @@ void __init jump_label_init(void)
> key->next = NULL;
> #endif
> }
> + static_key_initialized = true;
> jump_label_unlock();
> }
>



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