| Message ID | 20231013121029.353351-1-jiri@resnulli.us (mailing list archive) |
|---|---|
| Headers | show |
| Series | devlink: fix a deadlock when taking devlink instance lock while holding RTNL lock | expand |
Hello: This series was applied to netdev/net-next.git (main) by David S. Miller <davem@davemloft.net>: On Fri, 13 Oct 2023 14:10:22 +0200 you wrote: > From: Jiri Pirko <jiri@nvidia.com> > > devlink_port_fill() may be called sometimes with RTNL lock held. > When putting the nested port function devlink instance attrs, > current code takes nested devlink instance lock. In that case lock > ordering is wrong. > > [...] Here is the summary with links: - [net-next,v3,1/7] net: treat possible_net_t net pointer as an RCU one and add read_pnet_rcu() https://git.kernel.org/netdev/net-next/c/2034d90ae41a - [net-next,v3,2/7] devlink: call peernet2id_alloc() with net pointer under RCU read lock https://git.kernel.org/netdev/net-next/c/c503bc7df602 - [net-next,v3,3/7] devlink: take device reference for devlink object https://git.kernel.org/netdev/net-next/c/a380687200e0 - [net-next,v3,4/7] devlink: don't take instance lock for nested handle put https://git.kernel.org/netdev/net-next/c/b5f4e371336a - [net-next,v3,5/7] Documentation: devlink: add nested instance section https://git.kernel.org/netdev/net-next/c/b6f23b319aad - [net-next,v3,6/7] Documentation: devlink: add a note about RTNL lock into locking section https://git.kernel.org/netdev/net-next/c/bb11cf9b2c4a - [net-next,v3,7/7] devlink: document devlink_rel_nested_in_notify() function https://git.kernel.org/netdev/net-next/c/5d77371e8c85 You are awesome, thank you!
From: Jiri Pirko <jiri@nvidia.com> devlink_port_fill() may be called sometimes with RTNL lock held. When putting the nested port function devlink instance attrs, current code takes nested devlink instance lock. In that case lock ordering is wrong. Patch #1 is a dependency of patch #2. Patch #2 converts the peernet2id_alloc() call to rely in RCU so it could called without devlink instance lock. Patch #3 takes device reference for devlink instance making sure that device does not disappear before devlink_release() is called. Patch #4 benefits from the preparations done in patches #2 and #3 and removes the problematic nested devlink lock aquisition. Patched #5-#7 improve documentation to reflect this issue so it is avoided in the future. Jiri Pirko (7): net: treat possible_net_t net pointer as an RCU one and add read_pnet_rcu() devlink: call peernet2id_alloc() with net pointer under RCU read lock devlink: take device reference for devlink object devlink: don't take instance lock for nested handle put Documentation: devlink: add nested instance section Documentation: devlink: add a note about RTNL lock into locking section devlink: document devlink_rel_nested_in_notify() function Documentation/networking/devlink/index.rst | 28 ++++++++++++++++++ include/net/net_namespace.h | 15 ++++++++-- net/devlink/core.c | 34 ++++++++++++---------- net/devlink/netlink.c | 12 ++++++-- 4 files changed, 68 insertions(+), 21 deletions(-)