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-rw-r--r--fs/proc/proc_sysctl.c31
1 files changed, 18 insertions, 13 deletions
diff --git a/fs/proc/proc_sysctl.c b/fs/proc/proc_sysctl.c
index 8efb1e10b025..3e64c6502dc8 100644
--- a/fs/proc/proc_sysctl.c
+++ b/fs/proc/proc_sysctl.c
@@ -266,21 +266,19 @@ static void proc_sys_prune_dcache(struct ctl_table_header *head)
struct inode *inode, *prev = NULL;
struct proc_inode *ei;
- list_for_each_entry(ei, &head->inodes, sysctl_inodes) {
+ rcu_read_lock();
+ list_for_each_entry_rcu(ei, &head->inodes, sysctl_inodes) {
inode = igrab(&ei->vfs_inode);
if (inode) {
- spin_unlock(&sysctl_lock);
+ rcu_read_unlock();
iput(prev);
prev = inode;
d_prune_aliases(inode);
- spin_lock(&sysctl_lock);
+ rcu_read_lock();
}
}
- if (prev) {
- spin_unlock(&sysctl_lock);
- iput(prev);
- spin_lock(&sysctl_lock);
- }
+ rcu_read_unlock();
+ iput(prev);
}
/* called under sysctl_lock, will reacquire if has to wait */
@@ -296,10 +294,10 @@ static void start_unregistering(struct ctl_table_header *p)
p->unregistering = &wait;
spin_unlock(&sysctl_lock);
wait_for_completion(&wait);
- spin_lock(&sysctl_lock);
} else {
/* anything non-NULL; we'll never dereference it */
p->unregistering = ERR_PTR(-EINVAL);
+ spin_unlock(&sysctl_lock);
}
/*
* Prune dentries for unregistered sysctls: namespaced sysctls
@@ -310,6 +308,7 @@ static void start_unregistering(struct ctl_table_header *p)
* do not remove from the list until nobody holds it; walking the
* list in do_sysctl() relies on that.
*/
+ spin_lock(&sysctl_lock);
erase_header(p);
}
@@ -455,11 +454,17 @@ static struct inode *proc_sys_make_inode(struct super_block *sb,
inode->i_ino = get_next_ino();
ei = PROC_I(inode);
- ei->sysctl = head;
- ei->sysctl_entry = table;
spin_lock(&sysctl_lock);
- list_add(&ei->sysctl_inodes, &head->inodes);
+ if (unlikely(head->unregistering)) {
+ spin_unlock(&sysctl_lock);
+ iput(inode);
+ inode = NULL;
+ goto out;
+ }
+ ei->sysctl = head;
+ ei->sysctl_entry = table;
+ list_add_rcu(&ei->sysctl_inodes, &head->inodes);
head->count++;
spin_unlock(&sysctl_lock);
@@ -487,7 +492,7 @@ out:
void proc_sys_evict_inode(struct inode *inode, struct ctl_table_header *head)
{
spin_lock(&sysctl_lock);
- list_del(&PROC_I(inode)->sysctl_inodes);
+ list_del_rcu(&PROC_I(inode)->sysctl_inodes);
if (!--head->count)
kfree_rcu(head, rcu);
spin_unlock(&sysctl_lock);