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* [PATCH net-next 0/4] improve ethtool/rtnl vs devlink locking
@ 2021-10-30  4:06 Jakub Kicinski
  2021-10-30  4:06 ` [PATCH net-next 1/4] ethtool: push the rtnl_lock into dev_ethtool() Jakub Kicinski
                   ` (3 more replies)
  0 siblings, 4 replies; 6+ messages in thread
From: Jakub Kicinski @ 2021-10-30  4:06 UTC (permalink / raw)
  To: davem; +Cc: netdev, jiri, leon, mkubecek, andrew, f.fainelli, Jakub Kicinski

During ethtool netlink development we decided to move some of
the commmands to devlink. Since we don't want drivers to implement
both devlink and ethtool version of the commands ethtool ioctl
falls back to calling devlink. Unfortunately devlink locks must
be taken before rtnl_lock. This results in a questionable
dev_hold() / rtnl_unlock() / devlink / rtnl_lock() / dev_put()
pattern.

This method "works" but it working depends on drivers in question
not doing much in ethtool_ops->begin / complete, and on the netdev
not having needs_free_netdev set.

Since commit 437ebfd90a25 ("devlink: Count struct devlink consumers")
we can hold a reference on a devlink instance and prevent it from
going away (sort of like netdev with dev_hold()). We can use this
to create a more natural reference nesting where we get a ref on
the devlink instance and make the devlink call entirely outside
of the rtnl_lock section.

Jakub Kicinski (4):
  ethtool: push the rtnl_lock into dev_ethtool()
  ethtool: handle info/flash data copying outside rtnl_lock
  devlink: expose get/put functions
  ethtool: don't drop the rtnl_lock half way thru the ioctl

 include/net/devlink.h |  16 ++++-
 net/core/dev_ioctl.c  |   2 -
 net/core/devlink.c    |  53 ++++-----------
 net/ethtool/ioctl.c   | 148 ++++++++++++++++++++++++++++++------------
 4 files changed, 134 insertions(+), 85 deletions(-)

-- 
2.31.1


^ permalink raw reply	[flat|nested] 6+ messages in thread

end of thread, other threads:[~2021-10-30  8:51 UTC | newest]

Thread overview: 6+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2021-10-30  4:06 [PATCH net-next 0/4] improve ethtool/rtnl vs devlink locking Jakub Kicinski
2021-10-30  4:06 ` [PATCH net-next 1/4] ethtool: push the rtnl_lock into dev_ethtool() Jakub Kicinski
2021-10-30  4:06 ` [PATCH net-next 2/4] ethtool: handle info/flash data copying outside rtnl_lock Jakub Kicinski
2021-10-30  4:06 ` [PATCH net-next 3/4] devlink: expose get/put functions Jakub Kicinski
2021-10-30  4:06 ` [PATCH net-next 4/4] ethtool: don't drop the rtnl_lock half way thru the ioctl Jakub Kicinski
2021-10-30  8:50   ` kernel test robot

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