From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Date: Wed, 17 Oct 2012 23:36:11 +0000 (+1100)
Subject: Revert "powerpc/perf: Use pmc_overflow() to detect rolled back events"
X-Git-Tag: v3.7-rc2~28^2~4
X-Git-Url: https://asedeno.scripts.mit.edu/gitweb/?a=commitdiff_plain;h=72523d8082df3d89bffe30cbc1356dbb45ab51ae;p=linux.git

Revert "powerpc/perf: Use pmc_overflow() to detect rolled back events"

This reverts commit 813312110bede27bffd082c25cd31730bd567beb.

This revert was requested by the author of the patch as it seems
to cause system hangs with some low frequency events
---

diff --git a/arch/powerpc/perf/core-book3s.c b/arch/powerpc/perf/core-book3s.c
index 0db88f501f91..aa2465e21f1a 100644
--- a/arch/powerpc/perf/core-book3s.c
+++ b/arch/powerpc/perf/core-book3s.c
@@ -1463,7 +1463,7 @@ static void perf_event_interrupt(struct pt_regs *regs)
 		if (!event->hw.idx || is_limited_pmc(event->hw.idx))
 			continue;
 		val = read_pmc(event->hw.idx);
-		if (pmc_overflow(val)) {
+		if ((int)val < 0) {
 			/* event has overflowed */
 			found = 1;
 			record_and_restart(event, val, regs);