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Jarno Rajahalme authored
Reduce and clarify locking requirements for ovs_flow_cmd_alloc_info(), ovs_flow_cmd_fill_info() and ovs_flow_cmd_build_info(). A datapath pointer is available only when holding a lock. Change ovs_flow_cmd_fill_info() and ovs_flow_cmd_build_info() to take a dp_ifindex directly, rather than a datapath pointer that is then (only) used to get the dp_ifindex. This is useful, since the dp_ifindex is available even when the datapath pointer is not, both before and after taking a lock, which makes further critical section reduction possible. Make ovs_flow_cmd_alloc_info() take an 'acts' argument instead a 'flow' pointer. This allows some future patches to do the allocation before acquiring the flow pointer. The locking requirements after this patch are: ovs_flow_cmd_alloc_info(): May be called without locking, must not be called while holding the RCU read lock (due to memory allocation). If 'acts' belong to a flow in the flow table, however, then the caller must hold ovs_mutex. ovs_flow_cmd_fill_info(): Either ovs_mutex or RCU read lock must be held. ovs_flow_cmd_build_info(): This calls both of the above, so the caller must hold ovs_mutex. Signed-off-by: Jarno Rajahalme <jrajahalme@nicira.com> Signed-off-by: Pravin B Shelar <pshelar@nicira.com>
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