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| author | Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> | 2011-10-03 11:01:46 -0700 |
|---|---|---|
| committer | Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> | 2011-10-25 11:54:31 -0700 |
| commit | 20284aa77c0f6227da4783a920b72dc61d4bcc09 (patch) | |
| tree | 46fb708a9508e3d718be7eb432367547e71208d3 | |
| parent | 92e02396d7214fdc7c25239eb647eb48e6fe6ba9 (diff) | |
| download | lwn-20284aa77c0f6227da4783a920b72dc61d4bcc09.tar.gz lwn-20284aa77c0f6227da4783a920b72dc61d4bcc09.zip | |
jump_label: add arch_jump_label_transform_static() to optimise non-live code updates
When updating a newly loaded module, the code is definitely not yet
executing on any processor, so it can be updated with no need for any
heavyweight synchronization.
This patch adds arch_jump_label_static() which is implemented as
arch_jump_label_transform() by default, but architectures can override
it if it avoids, say, a call to stop_machine().
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Acked-by: Jason Baron <jbaron@redhat.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
| -rw-r--r-- | include/linux/jump_label.h | 2 | ||||
| -rw-r--r-- | kernel/jump_label.c | 18 |
2 files changed, 17 insertions, 3 deletions
diff --git a/include/linux/jump_label.h b/include/linux/jump_label.h index 12e804ea32ab..56594e45b011 100644 --- a/include/linux/jump_label.h +++ b/include/linux/jump_label.h @@ -45,6 +45,8 @@ extern void jump_label_lock(void); extern void jump_label_unlock(void); extern void arch_jump_label_transform(struct jump_entry *entry, enum jump_label_type type); +extern void arch_jump_label_transform_static(struct jump_entry *entry, + enum jump_label_type type); extern int jump_label_text_reserved(void *start, void *end); extern void jump_label_inc(struct jump_label_key *key); extern void jump_label_dec(struct jump_label_key *key); diff --git a/kernel/jump_label.c b/kernel/jump_label.c index 059202d5b77a..ff2028f35aa8 100644 --- a/kernel/jump_label.c +++ b/kernel/jump_label.c @@ -104,6 +104,18 @@ static int __jump_label_text_reserved(struct jump_entry *iter_start, return 0; } +/* + * Update code which is definitely not currently executing. + * Architectures which need heavyweight synchronization to modify + * running code can override this to make the non-live update case + * cheaper. + */ +void __weak arch_jump_label_transform_static(struct jump_entry *entry, + enum jump_label_type type) +{ + arch_jump_label_transform(entry, type); +} + static void __jump_label_update(struct jump_label_key *key, struct jump_entry *entry, struct jump_entry *stop, int enable) @@ -135,8 +147,8 @@ static __init int jump_label_init(void) struct jump_label_key *iterk; iterk = (struct jump_label_key *)(unsigned long)iter->key; - arch_jump_label_transform(iter, jump_label_enabled(iterk) ? - JUMP_LABEL_ENABLE : JUMP_LABEL_DISABLE); + arch_jump_label_transform_static(iter, jump_label_enabled(iterk) ? + JUMP_LABEL_ENABLE : JUMP_LABEL_DISABLE); if (iterk == key) continue; @@ -208,7 +220,7 @@ void jump_label_apply_nops(struct module *mod) return; for (iter = iter_start; iter < iter_stop; iter++) - arch_jump_label_transform(iter, JUMP_LABEL_DISABLE); + arch_jump_label_transform_static(iter, JUMP_LABEL_DISABLE); } static int jump_label_add_module(struct module *mod) |