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Date: Fri, 10 Aug 2007 10:52:33 +0200
From: Richard MUSIL <richard.musil@...com>
To: Richard Musil <richard.musil@...com>, Thomas Graf <tgraf@...g.ch>
Cc: Patrick McHardy <kaber@...sh.net>, netdev@...r.kernel.org
Subject: Re: [GENETLINK]: Question: global lock (genl_mutex) possible refinement?
Hello Thomas,
I wonder, if you had time to take a look at the patch I posted back then.
Richard
----
Thomas Graf wrote:
> > Please provide a new overall patch which is not based on your
> > initial patch so I can review your idea properly.
Here it goes (merging two previous patches). I have diffed
against v2.6.22, which I am using currently as my base:
include/net/genetlink.h | 1 +
net/netlink/genetlink.c | 106 +++++++++++++++++++++++++++++++++++------------
2 files changed, 80 insertions(+), 27 deletions(-)
diff --git a/include/net/genetlink.h b/include/net/genetlink.h
index b6eaca1..681ad13 100644
--- a/include/net/genetlink.h
+++ b/include/net/genetlink.h
@@ -25,6 +25,7 @@ struct genl_family
struct nlattr ** attrbuf; /* private */
struct list_head ops_list; /* private */
struct list_head family_list; /* private */
+ struct mutex lock; /* private */
};
/**
diff --git a/net/netlink/genetlink.c b/net/netlink/genetlink.c
index b9ab62f..0104267 100644
--- a/net/netlink/genetlink.c
+++ b/net/netlink/genetlink.c
@@ -38,6 +38,32 @@ static void genl_unlock(void)
genl_sock->sk_data_ready(genl_sock, 0);
}
+static DEFINE_MUTEX(genl_fam_mutex); /* serialization for family list management */
+
+static inline void genl_fam_lock(struct genl_family *family)
+{
+ mutex_lock(&genl_fam_mutex);
+ if (family)
+ mutex_lock(&family->lock);
+}
+
+static inline void genl_fam_unlock(struct genl_family *family)
+{
+ if (family)
+ mutex_unlock(&family->lock);
+ mutex_unlock(&genl_fam_mutex);
+}
+
+static inline void genl_onefam_lock(struct genl_family *family)
+{
+ mutex_lock(&family->lock);
+}
+
+static inline void genl_onefam_unlock(struct genl_family *family)
+{
+ mutex_unlock(&family->lock);
+}
+
#define GENL_FAM_TAB_SIZE 16
#define GENL_FAM_TAB_MASK (GENL_FAM_TAB_SIZE - 1)
@@ -150,9 +176,9 @@ int genl_register_ops(struct genl_family *family, struct genl_ops *ops)
if (ops->policy)
ops->flags |= GENL_CMD_CAP_HASPOL;
- genl_lock();
+ genl_fam_lock(family);
list_add_tail(&ops->ops_list, &family->ops_list);
- genl_unlock();
+ genl_fam_unlock(family);
genl_ctrl_event(CTRL_CMD_NEWOPS, ops);
err = 0;
@@ -180,16 +206,16 @@ int genl_unregister_ops(struct genl_family *family, struct genl_ops *ops)
{
struct genl_ops *rc;
- genl_lock();
+ genl_fam_lock(family);
list_for_each_entry(rc, &family->ops_list, ops_list) {
if (rc == ops) {
list_del(&ops->ops_list);
- genl_unlock();
+ genl_fam_unlock(family);
genl_ctrl_event(CTRL_CMD_DELOPS, ops);
return 0;
}
}
- genl_unlock();
+ genl_fam_unlock(family);
return -ENOENT;
}
@@ -216,8 +242,9 @@ int genl_register_family(struct genl_family *family)
goto errout;
INIT_LIST_HEAD(&family->ops_list);
+ mutex_init(&family->lock);
- genl_lock();
+ genl_fam_lock(family);
if (genl_family_find_byname(family->name)) {
err = -EEXIST;
@@ -251,14 +278,14 @@ int genl_register_family(struct genl_family *family)
family->attrbuf = NULL;
list_add_tail(&family->family_list, genl_family_chain(family->id));
- genl_unlock();
+ genl_fam_unlock(family);
genl_ctrl_event(CTRL_CMD_NEWFAMILY, family);
return 0;
errout_locked:
- genl_unlock();
+ genl_fam_unlock(family);
errout:
return err;
}
@@ -275,7 +302,7 @@ int genl_unregister_family(struct genl_family *family)
{
struct genl_family *rc;
- genl_lock();
+ genl_fam_lock(family);
list_for_each_entry(rc, genl_family_chain(family->id), family_list) {
if (family->id != rc->id || strcmp(rc->name, family->name))
@@ -283,14 +310,16 @@ int genl_unregister_family(struct genl_family *family)
list_del(&rc->family_list);
INIT_LIST_HEAD(&family->ops_list);
- genl_unlock();
+
+ genl_fam_unlock(family);
+ mutex_destroy(&family->lock);
kfree(family->attrbuf);
genl_ctrl_event(CTRL_CMD_DELFAMILY, family);
return 0;
}
- genl_unlock();
+ genl_fam_unlock(family);
return -ENOENT;
}
@@ -303,38 +332,57 @@ static int genl_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
struct genlmsghdr *hdr = nlmsg_data(nlh);
int hdrlen, err;
+ genl_fam_lock(NULL);
family = genl_family_find_byid(nlh->nlmsg_type);
- if (family == NULL)
+ if (family == NULL) {
+ genl_fam_unlock(NULL);
return -ENOENT;
+ }
+
+ /* get particular family lock, but release global family lock
+ * so registering operations for other families are possible */
+ genl_onefam_lock(family);
+ genl_fam_unlock(NULL);
hdrlen = GENL_HDRLEN + family->hdrsize;
- if (nlh->nlmsg_len < nlmsg_msg_size(hdrlen))
- return -EINVAL;
+ if (nlh->nlmsg_len < nlmsg_msg_size(hdrlen)) {
+ err = -EINVAL;
+ goto unlock_out;
+ }
ops = genl_get_cmd(hdr->cmd, family);
- if (ops == NULL)
- return -EOPNOTSUPP;
+ if (ops == NULL) {
+ err = -EOPNOTSUPP;
+ goto unlock_out;
+ }
if ((ops->flags & GENL_ADMIN_PERM) &&
- security_netlink_recv(skb, CAP_NET_ADMIN))
- return -EPERM;
+ security_netlink_recv(skb, CAP_NET_ADMIN)) {
+ err = -EPERM;
+ goto unlock_out;
+ }
if (nlh->nlmsg_flags & NLM_F_DUMP) {
- if (ops->dumpit == NULL)
- return -EOPNOTSUPP;
+ if (ops->dumpit == NULL) {
+ err = -EOPNOTSUPP;
+ goto unlock_out;
+ }
- return netlink_dump_start(genl_sock, skb, nlh,
+ err = netlink_dump_start(genl_sock, skb, nlh,
ops->dumpit, ops->done);
+ goto unlock_out;
}
- if (ops->doit == NULL)
- return -EOPNOTSUPP;
+ if (ops->doit == NULL) {
+ err = -EOPNOTSUPP;
+ goto unlock_out;
+ }
if (family->attrbuf) {
err = nlmsg_parse(nlh, hdrlen, family->attrbuf, family->maxattr,
ops->policy);
if (err < 0)
- return err;
+ goto unlock_out;
}
info.snd_seq = nlh->nlmsg_seq;
@@ -344,7 +392,11 @@ static int genl_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
info.userhdr = nlmsg_data(nlh) + GENL_HDRLEN;
info.attrs = family->attrbuf;
- return ops->doit(skb, &info);
+ err = ops->doit(skb, &info);
+
+unlock_out:
+ genl_onefam_unlock(family);
+ return err;
}
static void genl_rcv(struct sock *sk, int len)
@@ -425,7 +477,7 @@ static int ctrl_dumpfamily(struct sk_buff *skb, struct netlink_callback *cb)
int fams_to_skip = cb->args[1];
if (chains_to_skip != 0)
- genl_lock();
+ genl_fam_lock(NULL);
for (i = 0; i < GENL_FAM_TAB_SIZE; i++) {
if (i < chains_to_skip)
@@ -445,7 +497,7 @@ static int ctrl_dumpfamily(struct sk_buff *skb, struct netlink_callback *cb)
errout:
if (chains_to_skip != 0)
- genl_unlock();
+ genl_fam_unlock(NULL);
cb->args[0] = i;
cb->args[1] = n;
-
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