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Message-Id: <20210108002005.3429956-15-olteanv@gmail.com>
Date: Fri, 8 Jan 2021 02:20:01 +0200
From: Vladimir Oltean <olteanv@...il.com>
To: "David S . Miller" <davem@...emloft.net>,
Jakub Kicinski <kuba@...nel.org>,
Nikolay Aleksandrov <nikolay@...dia.com>
Cc: netdev@...r.kernel.org, Andrew Lunn <andrew@...n.ch>,
Florian Fainelli <f.fainelli@...il.com>,
Cong Wang <xiyou.wangcong@...il.com>,
Stephen Hemminger <stephen@...workplumber.org>,
Eric Dumazet <edumazet@...gle.com>,
George McCollister <george.mccollister@...il.com>,
Oleksij Rempel <o.rempel@...gutronix.de>,
Jay Vosburgh <j.vosburgh@...il.com>,
Veaceslav Falico <vfalico@...il.com>,
Andy Gospodarek <andy@...yhouse.net>,
Arnd Bergmann <arnd@...db.de>, Taehee Yoo <ap420073@...il.com>,
Jiri Pirko <jiri@...lanox.com>, Florian Westphal <fw@...len.de>
Subject: [PATCH v4 net-next 14/18] net: openvswitch: ensure dev_get_stats can sleep
From: Vladimir Oltean <vladimir.oltean@....com>
There is an effort to convert .ndo_get_stats64 to sleepable context, and
for that to work, we need to prevent callers of dev_get_stats from using
atomic locking.
The OVS vport driver calls ovs_vport_get_stats from
ovs_vport_cmd_fill_info, a function with 7 callers: 5 under ovs_lock() and
2 under rcu_read_lock(). The RCU-protected callers are the doit and
dumpit callbacks of the OVS_VPORT_CMD_GET genetlink event. Things have
been this way ever since the OVS introduction in commit ccb1352e76cf
("net: Add Open vSwitch kernel components."), probably so that
OVS_PORT_CMD_GET doesn't have to serialize with all the others through
ovs_mutex. Sadly, now they do have to, otherwise we don't have
protection while accessing the datapath and vport structures.
Convert all callers of ovs_vport_cmd_fill_info to assume ovs_mutex
protection. This means that we can get rid of the gfp argument, since
all callers are now sleepable, we can just use GFP_KERNEL for memory
allocation.
Signed-off-by: Vladimir Oltean <vladimir.oltean@....com>
---
Changes in v4:
Patch is new.
net/openvswitch/datapath.c | 38 ++++++++++++++++++--------------------
net/openvswitch/vport.c | 2 +-
2 files changed, 19 insertions(+), 21 deletions(-)
diff --git a/net/openvswitch/datapath.c b/net/openvswitch/datapath.c
index 5c60a23d0c27..bf22ac608487 100644
--- a/net/openvswitch/datapath.c
+++ b/net/openvswitch/datapath.c
@@ -1957,10 +1957,10 @@ static struct genl_family dp_datapath_genl_family __ro_after_init = {
.module = THIS_MODULE,
};
-/* Called with ovs_mutex or RCU read lock. */
+/* Called with ovs_mutex */
static int ovs_vport_cmd_fill_info(struct vport *vport, struct sk_buff *skb,
struct net *net, u32 portid, u32 seq,
- u32 flags, u8 cmd, gfp_t gfp)
+ u32 flags, u8 cmd)
{
struct ovs_header *ovs_header;
struct ovs_vport_stats vport_stats;
@@ -1981,7 +1981,7 @@ static int ovs_vport_cmd_fill_info(struct vport *vport, struct sk_buff *skb,
goto nla_put_failure;
if (!net_eq(net, dev_net(vport->dev))) {
- int id = peernet2id_alloc(net, dev_net(vport->dev), gfp);
+ int id = peernet2id_alloc(net, dev_net(vport->dev), GFP_KERNEL);
if (nla_put_s32(skb, OVS_VPORT_ATTR_NETNSID, id))
goto nla_put_failure;
@@ -2029,15 +2029,14 @@ struct sk_buff *ovs_vport_cmd_build_info(struct vport *vport, struct net *net,
if (!skb)
return ERR_PTR(-ENOMEM);
- retval = ovs_vport_cmd_fill_info(vport, skb, net, portid, seq, 0, cmd,
- GFP_KERNEL);
+ retval = ovs_vport_cmd_fill_info(vport, skb, net, portid, seq, 0, cmd);
if (retval)
return ERR_PTR(retval);
return skb;
}
-/* Called with ovs_mutex or RCU read lock. */
+/* Called with ovs_mutex */
static struct vport *lookup_vport(struct net *net,
const struct ovs_header *ovs_header,
struct nlattr *a[OVS_VPORT_ATTR_MAX + 1])
@@ -2176,7 +2175,7 @@ static int ovs_vport_cmd_new(struct sk_buff *skb, struct genl_info *info)
err = ovs_vport_cmd_fill_info(vport, reply, genl_info_net(info),
info->snd_portid, info->snd_seq, 0,
- OVS_VPORT_CMD_NEW, GFP_KERNEL);
+ OVS_VPORT_CMD_NEW);
if (err)
goto exit_unlock_free;
@@ -2238,7 +2237,7 @@ static int ovs_vport_cmd_set(struct sk_buff *skb, struct genl_info *info)
err = ovs_vport_cmd_fill_info(vport, reply, genl_info_net(info),
info->snd_portid, info->snd_seq, 0,
- OVS_VPORT_CMD_SET, GFP_KERNEL);
+ OVS_VPORT_CMD_SET);
if (err)
goto exit_unlock_free;
@@ -2279,7 +2278,7 @@ static int ovs_vport_cmd_del(struct sk_buff *skb, struct genl_info *info)
err = ovs_vport_cmd_fill_info(vport, reply, genl_info_net(info),
info->snd_portid, info->snd_seq, 0,
- OVS_VPORT_CMD_DEL, GFP_KERNEL);
+ OVS_VPORT_CMD_DEL);
if (err)
goto exit_unlock_free;
@@ -2320,22 +2319,22 @@ static int ovs_vport_cmd_get(struct sk_buff *skb, struct genl_info *info)
if (!reply)
return -ENOMEM;
- rcu_read_lock();
+ ovs_lock();
vport = lookup_vport(sock_net(skb->sk), ovs_header, a);
err = PTR_ERR(vport);
if (IS_ERR(vport))
goto exit_unlock_free;
err = ovs_vport_cmd_fill_info(vport, reply, genl_info_net(info),
info->snd_portid, info->snd_seq, 0,
- OVS_VPORT_CMD_GET, GFP_ATOMIC);
+ OVS_VPORT_CMD_GET);
if (err)
goto exit_unlock_free;
- rcu_read_unlock();
+ ovs_unlock();
return genlmsg_reply(reply, info);
exit_unlock_free:
- rcu_read_unlock();
+ ovs_unlock();
kfree_skb(reply);
return err;
}
@@ -2347,25 +2346,24 @@ static int ovs_vport_cmd_dump(struct sk_buff *skb, struct netlink_callback *cb)
int bucket = cb->args[0], skip = cb->args[1];
int i, j = 0;
- rcu_read_lock();
- dp = get_dp_rcu(sock_net(skb->sk), ovs_header->dp_ifindex);
+ ovs_lock();
+ dp = get_dp(sock_net(skb->sk), ovs_header->dp_ifindex);
if (!dp) {
- rcu_read_unlock();
+ ovs_unlock();
return -ENODEV;
}
for (i = bucket; i < DP_VPORT_HASH_BUCKETS; i++) {
struct vport *vport;
j = 0;
- hlist_for_each_entry_rcu(vport, &dp->ports[i], dp_hash_node) {
+ hlist_for_each_entry(vport, &dp->ports[i], dp_hash_node) {
if (j >= skip &&
ovs_vport_cmd_fill_info(vport, skb,
sock_net(skb->sk),
NETLINK_CB(cb->skb).portid,
cb->nlh->nlmsg_seq,
NLM_F_MULTI,
- OVS_VPORT_CMD_GET,
- GFP_ATOMIC) < 0)
+ OVS_VPORT_CMD_GET) < 0)
goto out;
j++;
@@ -2373,7 +2371,7 @@ static int ovs_vport_cmd_dump(struct sk_buff *skb, struct netlink_callback *cb)
skip = 0;
}
out:
- rcu_read_unlock();
+ ovs_unlock();
cb->args[0] = i;
cb->args[1] = j;
diff --git a/net/openvswitch/vport.c b/net/openvswitch/vport.c
index e66c949fd97a..ba1a52addff2 100644
--- a/net/openvswitch/vport.c
+++ b/net/openvswitch/vport.c
@@ -265,7 +265,7 @@ void ovs_vport_del(struct vport *vport)
*
* Retrieves transmit, receive, and error stats for the given device.
*
- * Must be called with ovs_mutex or rcu_read_lock.
+ * Must be called with ovs_mutex.
*/
int ovs_vport_get_stats(struct vport *vport, struct ovs_vport_stats *stats)
{
--
2.25.1
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