Re: request_module while holding rtnl semaphore

[Patrick McHardy <kaber@xxxxxxxxx>]

Thomas Graf wrote:

> > Of course, then there is no problem. Will you fix the request_module in
> > cls_api.c as well?
> Just saw your patch, never mind.
Oops, embarassing :) The cls_api.c changes in my patch only deal with
EAGAIN from act_api.c, but I didn't fix module loading in cls_api.c
itself. Patch on top of the previous ones attached, I will also update
the bitkeeper tree.

Regards
Patrick

# This is a BitKeeper generated diff -Nru style patch.
#
# ChangeSet
#   2005/01/11 23:15:28+01:00 kaber@xxxxxxxxxxxx 
#   [PKT_SCHED]: cls_api.c: drop rtnl for loading modules
#   
#   Signed-off-by: Patrick McHardy <kaber@xxxxxxxxx>
# 
# net/sched/cls_api.c
#   2005/01/11 23:15:20+01:00 kaber@xxxxxxxxxxxx +14 -5
#   [PKT_SCHED]: cls_api.c: drop rtnl for loading modules
#   
#   Signed-off-by: Patrick McHardy <kaber@xxxxxxxxx>
# 
diff -Nru a/net/sched/cls_api.c b/net/sched/cls_api.c
--- a/net/sched/cls_api.c       2005-01-11 23:17:58 +01:00
+++ b/net/sched/cls_api.c       2005-01-11 23:17:58 +01:00
@@ -219,20 +219,29 @@
                err = -ENOBUFS;
                if ((tp = kmalloc(sizeof(*tp), GFP_KERNEL)) == NULL)
                        goto errout;
+               err = -EINVAL;
                tp_ops = tcf_proto_lookup_ops(tca[TCA_KIND-1]);
+               if (tp_ops == NULL) {
 #ifdef CONFIG_KMOD
-               if (tp_ops==NULL && tca[TCA_KIND-1] != NULL) {
                        struct rtattr *kind = tca[TCA_KIND-1];
                        char name[IFNAMSIZ];
 
-                       if (rtattr_strlcpy(name, kind, IFNAMSIZ) < IFNAMSIZ) {
+                       if (kind != NULL &&
+                           rtattr_strlcpy(name, kind, IFNAMSIZ) < IFNAMSIZ) {
+                               rtnl_unlock();
                                request_module("cls_%s", name);
+                               rtnl_lock();
                                tp_ops = tcf_proto_lookup_ops(kind);
+                               /* We dropped the RTNL semaphore in order to
+                                * perform the module load.  So, even if we
+                                * succeeded in loading the module we have to
+                                * replay the request.  We indicate this using
+                                * -EAGAIN.
+                                */
+                               if (tp_ops != NULL)
+                                       err = -EAGAIN;
                        }
-               }
 #endif
-               if (tp_ops == NULL) {
-                       err = -EINVAL;
                        kfree(tp);
                        goto errout;
                }