tree 255a017e47aff33b910160161a55e7abd9d2cd5f
parent 416eb33cd60ef405e2860a186364e57bcb2d89f6
author Paul E. McKenney <paul.mckenney@linaro.org> 1318557912 -0700
committer Paul E. McKenney <paulmck@linux.vnet.ibm.com> 1323628299 -0800

powerpc: Tell RCU about idle after hcall tracing

The PowerPC pSeries platform (CONFIG_PPC_PSERIES=y) enables
hypervisor-call tracing for CONFIG_TRACEPOINTS=y kernels.  One of the
hypervisor calls that is traced is the H_CEDE call in the idle loop
that tells the hypervisor that this OS instance no longer needs the
current CPU.  However, tracing uses RCU, so this combination of kernel
configuration variables needs to avoid telling RCU about the current CPU's
idleness until after the H_CEDE-entry tracing completes on the one hand,
and must tell RCU that the the current CPU is no longer idle before the
H_CEDE-exit tracing starts.

In all other cases, it suffices to inform RCU of CPU idleness upon
idle-loop entry and exit.

This commit makes the required adjustments.

Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>