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[PATCH PKT_SCHED 4/6]: act_api.c: drop rtnl for loading modules

To: "David S. Miller" <davem@xxxxxxxxxxxxx>
Subject: [PATCH PKT_SCHED 4/6]: act_api.c: drop rtnl for loading modules
From: Patrick McHardy <kaber@xxxxxxxxx>
Date: Tue, 11 Jan 2005 22:46:30 +0100
Cc: Maillist netdev <netdev@xxxxxxxxxxx>
Sender: netdev-bounce@xxxxxxxxxxx
User-agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.7.3) Gecko/20041008 Debian/1.7.3-5

# This is a BitKeeper generated diff -Nru style patch.
#
# ChangeSet
#   2005/01/11 22:10:34+01:00 kaber@xxxxxxxxxxxx 
#   [PKT_SCHED]: act_api.c: drop rtnl for loading modules
#   
#   Signed-off-by: Patrick McHardy <kaber@xxxxxxxxx>
# 
# net/sched/cls_api.c
#   2005/01/11 22:10:27+01:00 kaber@xxxxxxxxxxxx +18 -7
#   [PKT_SCHED]: act_api.c: drop rtnl for loading modules
#   
#   Signed-off-by: Patrick McHardy <kaber@xxxxxxxxx>
# 
# net/sched/act_api.c
#   2005/01/11 22:10:26+01:00 kaber@xxxxxxxxxxxx +19 -4
#   [PKT_SCHED]: act_api.c: drop rtnl for loading modules
#   
#   Signed-off-by: Patrick McHardy <kaber@xxxxxxxxx>
# 
diff -Nru a/net/sched/act_api.c b/net/sched/act_api.c
--- a/net/sched/act_api.c       2005-01-11 22:32:20 +01:00
+++ b/net/sched/act_api.c       2005-01-11 22:32:20 +01:00
@@ -291,16 +291,28 @@
                        goto err_out;
        }
 
-       *err = -ENOENT;
        a_o = tc_lookup_action_n(act_name);
-#ifdef CONFIG_KMOD
        if (a_o == NULL) {
+#ifdef CONFIG_KMOD
+               rtnl_unlock();
                request_module(act_name);
+               rtnl_lock();
+
                a_o = tc_lookup_action_n(act_name);
-       }
+
+               /* We dropped the RTNL semaphore in order to
+                * perform the module load.  So, even if we
+                * succeeded in loading the module we have to
+                * tell the caller to replay the request.  We
+                * indicate this using -EAGAIN.
+                */
+               if (a_o != NULL) {
+                       *err = -EAGAIN;
+                       goto err_mod;
+               }
 #endif
-       if (a_o == NULL)
                goto err_out;
+       }
 
        *err = -ENOMEM;
        a = kmalloc(sizeof(*a), GFP_KERNEL);
@@ -740,7 +752,10 @@
                 */
                if (n->nlmsg_flags&NLM_F_REPLACE)
                        ovr = 1;
+replay:
                ret = tcf_action_add(tca[TCA_ACT_TAB-1], n, pid, ovr);
+               if (ret == -EAGAIN)
+                       goto replay;
                break;
        case RTM_DELACTION:
                ret = tca_action_gd(tca[TCA_ACT_TAB-1], n, pid, RTM_DELACTION);
diff -Nru a/net/sched/cls_api.c b/net/sched/cls_api.c
--- a/net/sched/cls_api.c       2005-01-11 22:32:20 +01:00
+++ b/net/sched/cls_api.c       2005-01-11 22:32:20 +01:00
@@ -130,22 +130,30 @@
 
 static int tc_ctl_tfilter(struct sk_buff *skb, struct nlmsghdr *n, void *arg)
 {
-       struct rtattr **tca = arg;
-       struct tcmsg *t = NLMSG_DATA(n);
-       u32 protocol = TC_H_MIN(t->tcm_info);
-       u32 prio = TC_H_MAJ(t->tcm_info);
-       u32 nprio = prio;
-       u32 parent = t->tcm_parent;
+       struct rtattr **tca;
+       struct tcmsg *t;
+       u32 protocol;
+       u32 prio;
+       u32 nprio;
+       u32 parent;
        struct net_device *dev;
        struct Qdisc  *q;
        struct tcf_proto **back, **chain;
-       struct tcf_proto *tp = NULL;
+       struct tcf_proto *tp;
        struct tcf_proto_ops *tp_ops;
        struct Qdisc_class_ops *cops;
        unsigned long cl = 0;
        unsigned long fh;
        int err;
 
+replay:
+       tca = arg;
+       t = NLMSG_DATA(n);
+       protocol = TC_H_MIN(t->tcm_info);
+       prio = TC_H_MAJ(t->tcm_info);
+       nprio = prio;
+       parent = t->tcm_parent;
+
        if (prio == 0) {
                /* If no priority is given, user wants we allocated it. */
                if (n->nlmsg_type != RTM_NEWTFILTER || 
!(n->nlmsg_flags&NLM_F_CREATE))
@@ -294,6 +302,9 @@
 errout:
        if (cl)
                cops->put(q, cl);
+       if (err == -EAGAIN)
+               /* Replay the request. */
+               goto replay;
        return err;
 }
 
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