Messages in this thread Patch in this message | | | From | Haibo Li <> | Subject | [PATCH v2 2/2] cfi: free old cfi shadow asynchronously | Date | Mon, 4 Jul 2022 09:40:46 +0800 |
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Currenly, it uses synchronize_rcu() to wait old rcu reader to go away in update_shadow.In embedded platform like ARM CA7X, load_module blocks 40~50ms in update_shadow. When there are more than one hundred kernel modules, it blocks several seconds.
To accelerate load_module,change synchronize_rcu to call_rcu.
Signed-off-by: Haibo Li <haibo.li@mediatek.com> Signed-off-by: Lecopzer Chen <lecopzer.chen@mediatek.com> --- kernel/cfi.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-)
diff --git a/kernel/cfi.c b/kernel/cfi.c index 6c8ae07b5835..f61439392bf8 100644 --- a/kernel/cfi.c +++ b/kernel/cfi.c @@ -43,6 +43,8 @@ typedef u16 shadow_t; struct cfi_shadow { /* Page index for the beginning of the shadow */ unsigned long base; + /* rcu to free old cfi_shadow asynchronously */ + struct rcu_head rcu; /* An array of __cfi_check locations (as indices to the shadow) */ shadow_t shadow[1]; } __packed; @@ -182,6 +184,13 @@ static void remove_module_from_shadow(struct cfi_shadow *s, struct module *mod, } } +static void free_shadow(struct rcu_head *rcu) +{ + struct cfi_shadow *old = container_of(rcu, struct cfi_shadow, rcu); + + vfree(old); +} + typedef void (*update_shadow_fn)(struct cfi_shadow *, struct module *, unsigned long min_addr, unsigned long max_addr); @@ -211,11 +220,10 @@ static void update_shadow(struct module *mod, unsigned long base_addr, rcu_assign_pointer(cfi_shadow, next); mutex_unlock(&shadow_update_lock); - synchronize_rcu(); if (prev) { set_memory_rw((unsigned long)prev, SHADOW_PAGES); - vfree(prev); + call_rcu(&prev->rcu, free_shadow); } } -- 2.25.1
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