Gitweb: http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=199f45...
Commit: 199f45c45e8d4f58a5f568464be933534460eb82
Parent: 2172fe8704a1df7cbb988ae1ec4edbfef3e28860
Author: Milton Miller <miltonm@bga.com>
AuthorDate: Fri Oct 10 01:56:44 2008 +0000
Committer: Benjamin Herrenschmidt <benh@kernel.crashing.org>
CommitDate: Mon Oct 13 16:24:19 2008 +1100
powerpc/xics: Reduce and comment xics IPI use of memory barriers
A single full sync (mb()) is requrired to order the mmio to the qirr reg
with the set or clear of the message word. However, test_and_clear_bit
has the effect of smp_mb() and we are not doing any other io from here,
so we don't need a mb per bit processed.
Signed-off-by: Milton Miller <miltonm@bga.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
---
arch/powerpc/platforms/pseries/xics.c | 5 +----
1 files changed, 1 insertions(+), 4 deletions(-)
diff --git a/arch/powerpc/platforms/pseries/xics.c b/arch/powerpc/platforms/pseries/xics.c
index 62b0400..e190477 100644
--- a/arch/powerpc/platforms/pseries/xics.c
+++ b/arch/powerpc/platforms/pseries/xics.c
@@ -498,26 +498,23 @@ static irqreturn_t xics_ipi_dispatch(int cpu)
{
WARN_ON(cpu_is_offline(cpu));
+ mb(); /* order mmio clearing qirr */
while (xics_ipi_message[cpu].value) {
if (test_and_clear_bit(PPC_MSG_CALL_FUNCTION,
&xics_ipi_message[cpu].value)) {
- mb();
smp_message_recv(PPC_MSG_CALL_FUNCTION);
}
if (test_and_clear_bit(PPC_MSG_RESCHEDULE,
&xics_ipi_message[cpu].value)) {
- mb();
smp_message_recv(PPC_MSG_RESCHEDULE);
}
if (test_and_clear_bit(PPC_MSG_CALL_FUNC_SINGLE,
&xics_ipi_message[cpu].value)) {
- mb();
smp_message_recv(PPC_MSG_CALL_FUNC_SINGLE);
}
#if defined(CONFIG_DEBUGGER) || defined(CONFIG_KEXEC)
if (test_and_clear_bit(PPC_MSG_DEBUGGER_BREAK,
&xics_ipi_message[cpu].value)) {
- mb();
smp_message_recv(PPC_MSG_DEBUGGER_BREAK);
}
#endif
--
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