devlink: protect devlink dump by the instance lock

[ Upstream commit 214964a13ab56a9757d146b79b468a7ca190fbfb ]

Take the instance lock around devlink_nl_fill() when dumping,
doit takes it already.

We are only dumping basic info so in the worst case we were risking
data races around the reload statistics. Until the big devlink mutex
was removed all relevant code was protected by it, so the missing
instance lock was not exposed.

Fixes: d3efc2a6a6d8 ("net: devlink: remove devlink_mutex")
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Link: https://lore.kernel.org/r/20221216044122.1863550-1-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/net/core/devlink.c b/net/core/devlink.c
index e8f1af4231db91e04121e41f5be474015b9e8db2..2aa77d4b80d0a777b72228922aa3a0c0657c8c65 100644 (file)
--- a/net/core/devlink.c
+++ b/net/core/devlink.c
@@ -1505,10 +1505,13 @@ static int devlink_nl_cmd_get_dumpit(struct sk_buff *msg,
                        continue;
                }
 
+               devl_lock(devlink);
                err = devlink_nl_fill(msg, devlink, DEVLINK_CMD_NEW,
                                      NETLINK_CB(cb->skb).portid,
                                      cb->nlh->nlmsg_seq, NLM_F_MULTI);
+               devl_unlock(devlink);
                devlink_put(devlink);
+
                if (err)
                        goto out;
                idx++;