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[5.12.227.87]) by smtp.gmail.com with ESMTPSA id h16sm4776714eji.110.2021.01.09.09.27.38 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 09 Jan 2021 09:27:39 -0800 (PST) From: Vladimir Oltean To: "David S . Miller" , Jakub Kicinski Cc: netdev@vger.kernel.org, Andrew Lunn , Florian Fainelli , Cong Wang , Stephen Hemminger , Eric Dumazet , George McCollister , Oleksij Rempel , Jay Vosburgh , Veaceslav Falico , Andy Gospodarek , Arnd Bergmann , Taehee Yoo , Jiri Pirko , Florian Westphal , Nikolay Aleksandrov , Pravin B Shelar , Sridhar Samudrala , Saeed Mahameed Subject: [PATCH v6 net-next 12/15] net: openvswitch: ensure dev_get_stats can sleep Date: Sat, 9 Jan 2021 19:26:21 +0200 Message-Id: <20210109172624.2028156-13-olteanv@gmail.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20210109172624.2028156-1-olteanv@gmail.com> References: <20210109172624.2028156-1-olteanv@gmail.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org X-Patchwork-Delegate: kuba@kernel.org From: Vladimir Oltean 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 --- Changes in v6: None. Changes in v5: None. 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 160b8dc453da..318caa8f12c2 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; @@ -2029,8 +2029,7 @@ 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); BUG_ON(retval == -EMSGSIZE); if (retval) return ERR_PTR(retval); @@ -2038,7 +2037,7 @@ struct sk_buff *ovs_vport_cmd_build_info(struct vport *vport, struct net *net, 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]) @@ -2177,7 +2176,7 @@ 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); BUG_ON(err == -EMSGSIZE); if (err) goto exit_unlock_free; @@ -2240,7 +2239,7 @@ 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); BUG_ON(err == -EMSGSIZE); if (err) goto exit_unlock_free; @@ -2282,7 +2281,7 @@ 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); BUG_ON(err == -EMSGSIZE); if (err) goto exit_unlock_free; @@ -2324,23 +2323,23 @@ 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); BUG_ON(err == -EMSGSIZE); 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; } @@ -2352,25 +2351,24 @@ 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++; @@ -2378,7 +2376,7 @@ 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) {