[net-next,00/19] ipmr: get rid of rwlocks

Message

Eric Dumazet June 22, 2022, 5:12 a.m. UTC

We need to get rid of rwlocks in networking stacks,
if read_lock() is (ab)used from softirq context.

As discussed recently [1], rwlock are unfair by design in this case,
and writers can starve and trigger soft lockups.

This series convert ipmr code (both IPv4 and IPv6 families)
to RCU and spinlocks.

[1] https://lkml.org/lkml/2022/6/17/272

Eric Dumazet (19):
  ip6mr: do not get a device reference in pim6_rcv()
  ipmr: add rcu protection over (struct vif_device)->dev
  ipmr: change igmpmsg_netlink_event() prototype
  ipmr: ipmr_cache_report() changes
  ipmr: do not acquire mrt_lock in __pim_rcv()
  ipmr: do not acquire mrt_lock in ioctl(SIOCGETVIFCNT)
  ipmr: do not acquire mrt_lock before calling ipmr_cache_unresolved()
  ipmr: do not acquire mrt_lock while calling ip_mr_forward()
  ipmr: do not acquire mrt_lock in ipmr_get_route()
  ip6mr: ip6mr_cache_report() changes
  ip6mr: do not acquire mrt_lock in pim6_rcv()
  ip6mr: do not acquire mrt_lock in ioctl(SIOCGETMIFCNT_IN6)
  ip6mr: do not acquire mrt_lock before calling ip6mr_cache_unresolved
  ip6mr: do not acquire mrt_lock while calling ip6_mr_forward()
  ip6mr: switch ip6mr_get_route() to rcu_read_lock()
  ipmr: adopt rcu_read_lock() in mr_dump()
  ipmr: conver /proc handlers to rcu_read_lock()
  ipmr: convert mrt_lock to a spinlock
  ip6mr: convert mrt_lock to a spinlock

 include/linux/mroute_base.h |  15 ++-
 net/ipv4/ipmr.c             | 215 +++++++++++++++++++-----------------
 net/ipv4/ipmr_base.c        |  53 +++++----
 net/ipv6/ip6mr.c            | 202 ++++++++++++++++-----------------
 4 files changed, 255 insertions(+), 230 deletions(-)

Comments

Jakub Kicinski June 23, 2022, 12:34 a.m. UTC | #1

On Wed, 22 Jun 2022 05:12:36 +0000 Eric Dumazet wrote:
>   ipmr: conver /proc handlers to rcu_read_lock()

convert

>   ipmr: convert mrt_lock to a spinlock
>   ip6mr: convert mrt_lock to a spinlock

patch 19 did not make it :(