powerpc/nvram: Don't overwrite oops/panic report on normal shutdown

For normal halt, reboot, and poweroff events, refrain from overwriting
the lnx,oops-log partition.  Also, don't save the dmesg buffer on an
emergency-restart event if we've already saved it earlier in panic().

Signed-off-by: Jim Keniston <jkenisto@us.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

1 files changed, 24 insertions, 0 deletions

diff --git a/arch/powerpc/platforms/pseries/nvram.c b/arch/powerpc/platforms/pseries/nvram.c
index 419707b07248..00cc3a094885 100644
--- a/arch/powerpc/platforms/pseries/nvram.c
+++ b/arch/powerpc/platforms/pseries/nvram.c
@@ -480,8 +480,32 @@ static void oops_to_nvram(struct kmsg_dumper *dumper,
                 const char *new_msgs, unsigned long new_len)
 {
         static unsigned int oops_count = 0;
+        static bool panicking = false;
         size_t text_len;
 
+        switch (reason) {
+        case KMSG_DUMP_RESTART:
+        case KMSG_DUMP_HALT:
+        case KMSG_DUMP_POWEROFF:
+                /* These are almost always orderly shutdowns. */
+                return;
+        case KMSG_DUMP_OOPS:
+        case KMSG_DUMP_KEXEC:
+                break;
+        case KMSG_DUMP_PANIC:
+                panicking = true;
+                break;
+        case KMSG_DUMP_EMERG:
+                if (panicking)
+                        /* Panic report already captured. */
+                        return;
+                break;
+        default:
+                pr_err("%s: ignoring unrecognized KMSG_DUMP_* reason %d\n",
+                                                __FUNCTION__, (int) reason);
+                return;
+        }
+
         if (clobbering_unread_rtas_event())
                 return;