• Vlad Buslov's avatar
    net: sched: take reference to psample group in flow_action infra · 4a5da47d
    Vlad Buslov authored
    With recent patch set that removed rtnl lock dependency from cls hardware
    offload API rtnl lock is only taken when reading action data and can be
    released after action-specific data is parsed into intermediate
    representation. However, sample action psample group is passed by pointer
    without obtaining reference to it first, which makes it possible to
    concurrently overwrite the action and deallocate object pointed by
    psample_group pointer after rtnl lock is released but before driver
    finished using the pointer.
    
    To prevent such race condition, obtain reference to psample group while it
    is used by flow_action infra. Extend psample API with function
    psample_group_take() that increments psample group reference counter.
    Extend struct tc_action_ops with new get_psample_group() API. Implement the
    API for action sample using psample_group_take() and already existing
    psample_group_put() as a destructor. Use it in tc_setup_flow_action() to
    take reference to psample group pointed to by entry->sample.psample_group
    and release it in tc_cleanup_flow_action().
    
    Disable bh when taking psample_groups_lock. The lock is now taken while
    holding action tcf_lock that is used by data path and requires bh to be
    disabled, so doing the same for psample_groups_lock is necessary to
    preserve SOFTIRQ-irq-safety.
    
    Fixes: 918190f5 ("net: sched: flower: don't take rtnl lock for cls hw offloads API")
    Signed-off-by: default avatarVlad Buslov <vladbu@mellanox.com>
    Acked-by: default avatarJiri Pirko <jiri@mellanox.com>
    Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
    4a5da47d
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