| From | Lucian Adrian Grijincu <> | Subject | [v2 075/115] sysctl: move removal from list out of start_unregistering | Date | Mon, 9 May 2011 00:39:27 +0200 |
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Later on we'll switch form a global list protected by the sysctl_lock spin lock to rwsem protected per-header lists.
At that point we'll need to hold the parent header's rwlock to remove the header from the list, not the sysctl_lock spin lock.
As start_unregistering is called under the sysctl_lock, we move the list removal out.
Signed-off-by: Lucian Adrian Grijincu <lucian.grijincu@gmail.com> --- kernel/sysctl.c | 12 +++++++----- 1 files changed, 7 insertions(+), 5 deletions(-)
diff --git a/kernel/sysctl.c b/kernel/sysctl.c index 8dde087..a863b56 100644 --- a/kernel/sysctl.c +++ b/kernel/sysctl.c @@ -1552,11 +1552,6 @@ static void start_unregistering(struct ctl_table_header *p) /* anything non-NULL; we'll never dereference it */ p->unregistering = ERR_PTR(-EINVAL); } - /* - * do not remove from the list until nobody holds it; walking the - * list in do_sysctl() relies on that. - */ - list_del_init(&p->ctl_entry); } void sysctl_proc_inode_get(struct ctl_table_header *head) @@ -1949,6 +1944,13 @@ void unregister_sysctl_table(struct ctl_table_header * header) spin_lock(&sysctl_lock); start_unregistering(header); + + /* after start_unregistering has finished no one holds a + * ctl_use_refs or is able to acquire one => no one is going + * to access internal fields of this object, so we can remove + * it from the list and schedule it for deletion. */ + list_del_init(&p->ctl_entry); + if (!--header->parent->ctl_header_refs) { WARN_ON(1); if (!header->parent->ctl_procfs_refs) -- 1.7.5.134.g1c08b
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