Re: deadlock fixes

On Thu, Apr 27, 2006 at 07:27:25AM -0400, Alexander Viro wrote: Patch in question (thanks to Steve for reminding to send it to list): diff --git a/kernel/audit.c b/kernel/audit.c --- a/kernel/audit.c +++ b/kernel/audit.c @@ -368,6 +368,46 @@ static int kauditd_thread(void *dummy) return 0; } +int audit_send_list(void *_dest) +{ + struct audit_netlink_list *dest = _dest; + int pid = dest->pid; + struct sk_buff *skb; + + while ((skb = __skb_dequeue(&dest->q)) != NULL) + netlink_unicast(audit_sock, skb, pid, 0); + + kfree(dest); + + return 0; +} + +struct sk_buff *audit_make_reply(int pid, int seq, int type, int done, + int multi, void *payload, int size) +{ + struct sk_buff *skb; + struct nlmsghdr *nlh; + int len = NLMSG_SPACE(size); + void *data; + int flags = multi ? NLM_F_MULTI : 0; + int t = done ? NLMSG_DONE : type; + + skb = alloc_skb(len, GFP_KERNEL); + if (!skb) + return NULL; + + nlh = NLMSG_PUT(skb, pid, seq, t, size); + nlh->nlmsg_flags = flags; + data = NLMSG_DATA(nlh); + memcpy(data, payload, size); + return skb; + +nlmsg_failure: /* Used by NLMSG_PUT */ + if (skb) + kfree_skb(skb); + return NULL; +} + /** * audit_send_reply - send an audit reply message via netlink * @pid: process id to send reply to @@ -385,29 +425,13 @@ void audit_send_reply(int pid, int seq, void *payload, int size) { struct sk_buff *skb; - struct nlmsghdr *nlh; - int len = NLMSG_SPACE(size); - void *data; - int flags = multi ? NLM_F_MULTI : 0; - int t = done ? NLMSG_DONE : type; - - skb = alloc_skb(len, GFP_KERNEL); + skb = audit_make_reply(pid, seq, type, done, multi, payload, size); if (!skb) return; - - nlh = NLMSG_PUT(skb, pid, seq, t, size); - nlh->nlmsg_flags = flags; - data = NLMSG_DATA(nlh); - memcpy(data, payload, size); - /* Ignore failure. It'll only happen if the sender goes away, because our timeout is set to infinite. */ netlink_unicast(audit_sock, skb, pid, 0); return; - -nlmsg_failure: /* Used by NLMSG_PUT */ - if (skb) - kfree_skb(skb); } /* diff --git a/kernel/audit.h b/kernel/audit.h --- a/kernel/audit.h +++ b/kernel/audit.h @@ -95,12 +95,22 @@ struct audit_entry { extern int audit_pid; extern int audit_comparator(const u32 left, const u32 op, const u32 right); extern int audit_compare_dname_path(const char *dname, const char *path); +extern struct sk_buff * audit_make_reply(int pid, int seq, int type, + int done, int multi, + void *payload, int size); extern void audit_send_reply(int pid, int seq, int type, int done, int multi, void *payload, int size); extern void audit_log_lost(const char *message); extern void audit_panic(const char *message); +struct audit_netlink_list { + int pid; + struct sk_buff_head q; +}; + +int audit_send_list(void *); + struct inotify_watch; extern void audit_handle_ievent(struct inotify_watch *, u32, u32, u32, const char *, struct inode *); diff --git a/kernel/auditfilter.c b/kernel/auditfilter.c --- a/kernel/auditfilter.c +++ b/kernel/auditfilter.c @@ -1065,19 +1065,12 @@ static inline int audit_del_rule(struct /* List rules using struct audit_rule. Exists for backward * compatibility with userspace. */ -static int audit_list(void *_dest) +static void audit_list(int pid, int seq, struct sk_buff_head *q) { - int pid, seq; - int *dest = _dest; + struct sk_buff *skb; struct audit_entry *entry; int i; - pid = dest[0]; - seq = dest[1]; - kfree(dest); - - mutex_lock(&audit_filter_mutex); - /* This is a blocking read, so use audit_filter_mutex instead of rcu * iterator to sync with list writers. */ for (i=0; i<AUDIT_NR_FILTERS; i++) { @@ -1087,31 +1080,25 @@ static int audit_list(void *_dest) rule = audit_krule_to_rule(&entry->rule); if (unlikely(!rule)) break; - audit_send_reply(pid, seq, AUDIT_LIST, 0, 1, + skb = audit_make_reply(pid, seq, AUDIT_LIST, 0, 1, rule, sizeof(*rule)); + if (skb) + skb_queue_tail(q, skb); kfree(rule); } } - audit_send_reply(pid, seq, AUDIT_LIST, 1, 1, NULL, 0); - - mutex_unlock(&audit_filter_mutex); - return 0; + skb = audit_make_reply(pid, seq, AUDIT_LIST, 1, 1, NULL, 0); + if (skb) + skb_queue_tail(q, skb); } /* List rules using struct audit_rule_data. */ -static int audit_list_rules(void *_dest) +static void audit_list_rules(int pid, int seq, struct sk_buff_head *q) { - int pid, seq; - int *dest = _dest; + struct sk_buff *skb; struct audit_entry *e; int i; - pid = dest[0]; - seq = dest[1]; - kfree(dest); - - mutex_lock(&audit_filter_mutex); - /* This is a blocking read, so use audit_filter_mutex instead of rcu * iterator to sync with list writers. */ for (i=0; i<AUDIT_NR_FILTERS; i++) { @@ -1121,15 +1108,16 @@ static int audit_list_rules(void *_dest) data = audit_krule_to_data(&e->rule); if (unlikely(!data)) break; - audit_send_reply(pid, seq, AUDIT_LIST_RULES, 0, 1, + skb = audit_make_reply(pid, seq, AUDIT_LIST_RULES, 0, 1, data, sizeof(*data) + data->buflen); + if (skb) + skb_queue_tail(q, skb); kfree(data); } } - audit_send_reply(pid, seq, AUDIT_LIST_RULES, 1, 1, NULL, 0); - - mutex_unlock(&audit_filter_mutex); - return 0; + skb = audit_make_reply(pid, seq, AUDIT_LIST_RULES, 1, 1, NULL, 0); + if (skb) + skb_queue_tail(q, skb); } /** @@ -1147,7 +1135,7 @@ int audit_receive_filter(int type, int p size_t datasz, uid_t loginuid, u32 sid) { struct task_struct *tsk; - int *dest; + struct audit_netlink_list *dest; int err = 0; struct audit_entry *entry; @@ -1160,18 +1148,22 @@ int audit_receive_filter(int type, int p * happen if we're actually running in the context of auditctl * trying to _send_ the stuff */ - dest = kmalloc(2 * sizeof(int), GFP_KERNEL); + dest = kmalloc(sizeof(struct audit_netlink_list), GFP_KERNEL); if (!dest) return -ENOMEM; - dest[0] = pid; - dest[1] = seq; + dest->pid = pid; + skb_queue_head_init(&dest->q); + mutex_lock(&audit_filter_mutex); if (type == AUDIT_LIST) - tsk = kthread_run(audit_list, dest, "audit_list"); + audit_list(pid, seq, &dest->q); else - tsk = kthread_run(audit_list_rules, dest, - "audit_list_rules"); + audit_list_rules(pid, seq, &dest->q); + mutex_unlock(&audit_filter_mutex); + + tsk = kthread_run(audit_send_list, dest, "audit_send_list"); if (IS_ERR(tsk)) { + skb_queue_purge(&dest->q); kfree(dest); err = PTR_ERR(tsk); } -- 0.99.9.GIT