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 b3a869ccc8ed6fc43a6cd9cea7b9a3875917ba22..5f894bd20c3103c49030119c0d3c74ba8e79c61d 100644 (file)
--- a/net/core/devlink.c
+++ b/net/core/devlink.c
@@ -1498,10 +1498,13 @@ 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++;