| Message ID | 20180717193504.1d76fb1a43d0c8687d969143@linux-foundation.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Tue, Jul 17, 2018 at 07:35:04PM -0700, Andrew Morton wrote: > On Thu, 12 Jul 2018 17:09:33 -0700 Omar Sandoval <osandov@osandov.com> wrote: > > > From: Omar Sandoval <osandov@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. > > > > ... > > > > --- a/fs/proc/kcore.c > > +++ b/fs/proc/kcore.c > > @@ -62,6 +62,7 @@ static LIST_HEAD(kclist_head); > > static DEFINE_RWLOCK(kclist_lock); > > static int kcore_need_update = 1; > > > > +/* This doesn't grab kclist_lock, so it should only be used at init time. */ > > void > > kclist_add(struct kcore_list *new, void *addr, size_t size, int type) > > { > > @@ -69,9 +70,7 @@ kclist_add(struct kcore_list *new, void *addr, size_t size, int type) > > new->size = size; > > new->type = type; > > > > - write_lock(&kclist_lock); > > list_add_tail(&new->list, &kclist_head); > > - write_unlock(&kclist_lock); > > } > > So we can mark kclist_add() as __init, yes? Yes, thanks, I'll add that in v2. > That way we save a scrap of ram and if someone starts calling > kclist_add() from non-__init code we get a build-time warning. > > --- a/fs/proc/kcore.c~proc-kcore-dont-grab-lock-for-kclist_add-fix > +++ a/fs/proc/kcore.c > @@ -63,7 +63,7 @@ static DEFINE_RWLOCK(kclist_lock); > static int kcore_need_update = 1; > > /* This doesn't grab kclist_lock, so it should only be used at init time. */ > -void > +void __init > kclist_add(struct kcore_list *new, void *addr, size_t size, int type) > { > new->addr = (unsigned long)addr; > --- a/include/linux/kcore.h~proc-kcore-dont-grab-lock-for-kclist_add-fix > +++ a/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); > +extern 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) > >
--- a/fs/proc/kcore.c~proc-kcore-dont-grab-lock-for-kclist_add-fix +++ a/fs/proc/kcore.c @@ -63,7 +63,7 @@ static DEFINE_RWLOCK(kclist_lock); static int kcore_need_update = 1; /* This doesn't grab kclist_lock, so it should only be used at init time. */ -void +void __init kclist_add(struct kcore_list *new, void *addr, size_t size, int type) { new->addr = (unsigned long)addr; --- a/include/linux/kcore.h~proc-kcore-dont-grab-lock-for-kclist_add-fix +++ a/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); +extern 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)