diff options
| -rw-r--r-- | fs/proc/inode.c | 8 | ||||
| -rw-r--r-- | fs/proc/proc_sysctl.c | 7 | ||||
| -rw-r--r-- | include/linux/sysctl.h | 14 | ||||
| -rw-r--r-- | kernel/sysctl.c | 15 |
4 files changed, 31 insertions, 13 deletions
diff --git a/fs/proc/inode.c b/fs/proc/inode.c index 176ce4cda68..d6a7ca1fdac 100644 --- a/fs/proc/inode.c +++ b/fs/proc/inode.c @@ -27,6 +27,7 @@ static void proc_evict_inode(struct inode *inode) { struct proc_dir_entry *de; + struct ctl_table_header *head; truncate_inode_pages(&inode->i_data, 0); end_writeback(inode); @@ -38,8 +39,11 @@ static void proc_evict_inode(struct inode *inode) de = PROC_I(inode)->pde; if (de) pde_put(de); - if (PROC_I(inode)->sysctl) - sysctl_head_put(PROC_I(inode)->sysctl); + head = PROC_I(inode)->sysctl; + if (head) { + rcu_assign_pointer(PROC_I(inode)->sysctl, NULL); + sysctl_head_put(head); + } } struct vfsmount *proc_mnt; diff --git a/fs/proc/proc_sysctl.c b/fs/proc/proc_sysctl.c index 09a1f92a34e..8eb2522111c 100644 --- a/fs/proc/proc_sysctl.c +++ b/fs/proc/proc_sysctl.c @@ -408,15 +408,18 @@ static int proc_sys_compare(const struct dentry *parent, const struct dentry *dentry, const struct inode *inode, unsigned int len, const char *str, const struct qstr *name) { + struct ctl_table_header *head; /* Although proc doesn't have negative dentries, rcu-walk means * that inode here can be NULL */ + /* AV: can it, indeed? */ if (!inode) - return 0; + return 1; if (name->len != len) return 1; if (memcmp(name->name, str, len)) return 1; - return !sysctl_is_seen(PROC_I(inode)->sysctl); + head = rcu_dereference(PROC_I(inode)->sysctl); + return !head || !sysctl_is_seen(head); } static const struct dentry_operations proc_sys_dentry_operations = { diff --git a/include/linux/sysctl.h b/include/linux/sysctl.h index 7bb5cb64f3b..bb7c2b086fa 100644 --- a/include/linux/sysctl.h +++ b/include/linux/sysctl.h @@ -25,6 +25,7 @@ #include <linux/kernel.h> #include <linux/types.h> #include <linux/compiler.h> +#include <linux/rcupdate.h> struct completion; @@ -1037,10 +1038,15 @@ struct ctl_table_root { struct ctl_table trees. */ struct ctl_table_header { - struct ctl_table *ctl_table; - struct list_head ctl_entry; - int used; - int count; + union { + struct { + struct ctl_table *ctl_table; + struct list_head ctl_entry; + int used; + int count; + }; + struct rcu_head rcu; + }; struct completion *unregistering; struct ctl_table *ctl_table_arg; struct ctl_table_root *root; diff --git a/kernel/sysctl.c b/kernel/sysctl.c index 0f1bd83db98..4eed0af5d14 100644 --- a/kernel/sysctl.c +++ b/kernel/sysctl.c @@ -194,9 +194,9 @@ static int sysrq_sysctl_handler(ctl_table *table, int write, static struct ctl_table root_table[]; static struct ctl_table_root sysctl_table_root; static struct ctl_table_header root_table_header = { - .count = 1, + {{.count = 1, .ctl_table = root_table, - .ctl_entry = LIST_HEAD_INIT(sysctl_table_root.default_set.list), + .ctl_entry = LIST_HEAD_INIT(sysctl_table_root.default_set.list),}}, .root = &sysctl_table_root, .set = &sysctl_table_root.default_set, }; @@ -1567,11 +1567,16 @@ void sysctl_head_get(struct ctl_table_header *head) spin_unlock(&sysctl_lock); } +static void free_head(struct rcu_head *rcu) +{ + kfree(container_of(rcu, struct ctl_table_header, rcu)); +} + void sysctl_head_put(struct ctl_table_header *head) { spin_lock(&sysctl_lock); if (!--head->count) - kfree(head); + call_rcu(&head->rcu, free_head); spin_unlock(&sysctl_lock); } @@ -1948,10 +1953,10 @@ void unregister_sysctl_table(struct ctl_table_header * header) start_unregistering(header); if (!--header->parent->count) { WARN_ON(1); - kfree(header->parent); + call_rcu(&header->parent->rcu, free_head); } if (!--header->count) - kfree(header); + call_rcu(&header->rcu, free_head); spin_unlock(&sysctl_lock); } |