[PATCH v4 1/9] proc/kcore: don't grab lock for kclist_add()

[Omar Sandoval]

From: Omar Sandoval <osan...@fb.com>

kclist_add() is only called at init time, so there's no point in
grabbing any locks. We're also going to replace the rwlock with a rwsem,
which we don't want to try grabbing during early boot.

While we're here, mark kclist_add() with __init so that we'll get a
warning if it's called from non-init code.

Reviewed-by: Andrew Morton <a...@linux-foundation.org>
Signed-off-by: Omar Sandoval <osan...@fb.com>
---
 fs/proc/kcore.c       | 7 +++----
 include/linux/kcore.h | 2 +-
 2 files changed, 4 insertions(+), 5 deletions(-)

diff --git a/fs/proc/kcore.c b/fs/proc/kcore.c
index 66c373230e60..b0b9a76f28d6 100644
--- a/fs/proc/kcore.c
+++ b/fs/proc/kcore.c
@@ -62,16 +62,15 @@ static LIST_HEAD(kclist_head);
 static DEFINE_RWLOCK(kclist_lock);
 static int kcore_need_update = 1;
 
-void
-kclist_add(struct kcore_list *new, void *addr, size_t size, int type)
+/* This doesn't grab kclist_lock, so it should only be used at init time. */
+void __init kclist_add(struct kcore_list *new, void *addr, size_t size,
+                      int type)
 {
        new->addr = (unsigned long)addr;
        new->size = size;
        new->type = type;
 
-       write_lock(&kclist_lock);
        list_add_tail(&new->list, &kclist_head);
-       write_unlock(&kclist_lock);
 }
 
 static size_t get_kcore_size(int *nphdr, size_t *elf_buflen)
diff --git a/include/linux/kcore.h b/include/linux/kcore.h
index 8de55e4b5ee9..c20f296438fb 100644
--- a/include/linux/kcore.h
+++ b/include/linux/kcore.h
@@ -35,7 +35,7 @@ struct vmcoredd_node {
 };
 
 #ifdef CONFIG_PROC_KCORE
-extern void kclist_add(struct kcore_list *, void *, size_t, int type);
+void __init kclist_add(struct kcore_list *, void *, size_t, int type);
 #else
 static inline
 void kclist_add(struct kcore_list *new, void *addr, size_t size, int type)
-- 
2.18.0