[PATCH v2] powernv: don't attempt to refetch the FSP dump until the user has explicitly acked it.

[Stewart Smith]

This fixes a bug where we would get two events from OPAL with DUMP_AVAIL
set (which is valid for OPAL to do) and in the second run of extract_dump()
we would fail to free the memory previously allocated for the dump
(leaking ~6MB+) as well as on the second dump_read_data() call OPAL
would not retrieve the dump, leaving us with a dump in linux that was
the correct size but all zeros.

Changes since v1: fixed typo

Signed-off-by: Stewart Smith <stewart at linux.vnet.ibm.com>
Acked-by: Benjamin Herrenschmidt <benh at kernel.crashing.org>
---
 arch/powerpc/platforms/powernv/opal-dump.c |    8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/arch/powerpc/platforms/powernv/opal-dump.c b/arch/powerpc/platforms/powernv/opal-dump.c
index 4447027..53c2675 100644
--- a/arch/powerpc/platforms/powernv/opal-dump.c
+++ b/arch/powerpc/platforms/powernv/opal-dump.c
@@ -238,6 +238,14 @@ static int extract_dump(void)
 {
 	int rc;
 
+	/* We can get notified that a dump is available multiple times
+	 * (dump_read_info clears the bit in the event from OPAL).
+	 * But we should not re-read the dump from OPAL as we
+	 * don't get the next dump until we've explicitly acked this one.
+	 */
+	if (dump_avail)
+		return OPAL_SUCCESS;
+
 	/* Get dump ID, size */
 	rc = dump_read_info();
 	if (rc != OPAL_SUCCESS)
-- 
1.7.10.4