rcu: Make rcu_assign_pointer() unconditionally insert a memory barrier
Recent changes to gcc give warning messages on rcu_assign_pointers()'s checks that allow it to determine when it is OK to omit the memory barrier. Stephen Hemminger tried a number of gcc tricks to silence this warning, but #pragmas and CPP macros do not work together in the way that would be required to make this work. However, we now have RCU_INIT_POINTER(), which already omits this memory barrier, and which therefore may be used when assigning NULL to an RCU-protected pointer that is accessible to readers. This commit therefore makes rcu_assign_pointer() unconditionally emit the memory barrier. Reported-by: NStephen Hemminger <shemminger@vyatta.com> Signed-off-by: NEric Dumazet <eric.dumazet@gmail.com> Acked-by: NDavid S. Miller <davem@davemloft.net> Signed-off-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com>
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