[PATCH 2/2] powerpc/powernv: Fix NVRAM sleep in invalid context when crashing

[Nicholas Piggin]

Similarly to opal_event_shutdown, opal_nvram_write can be called in
the crash path with irqs disabled. Special case the delay to avoid
sleeping in invalid context.

Cc: sta...@vger.kernel.org # v3.2
Fixes: 3b8070335f ("powerpc/powernv: Fix OPAL NVRAM driver OPAL_BUSY loops")
Signed-off-by: Nicholas Piggin <npig...@gmail.com>
---
 arch/powerpc/platforms/powernv/opal-nvram.c | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/platforms/powernv/opal-nvram.c 
b/arch/powerpc/platforms/powernv/opal-nvram.c
index 1bceb95f422d..5584247f5029 100644
--- a/arch/powerpc/platforms/powernv/opal-nvram.c
+++ b/arch/powerpc/platforms/powernv/opal-nvram.c
@@ -44,6 +44,10 @@ static ssize_t opal_nvram_read(char *buf, size_t count, 
loff_t *index)
        return count;
 }
 
+/*
+ * This can be called in the panic path with interrupts off, so use
+ * mdelay in that case.
+ */
 static ssize_t opal_nvram_write(char *buf, size_t count, loff_t *index)
 {
        s64 rc = OPAL_BUSY;
@@ -58,10 +62,16 @@ static ssize_t opal_nvram_write(char *buf, size_t count, 
loff_t *index)
        while (rc == OPAL_BUSY || rc == OPAL_BUSY_EVENT) {
                rc = opal_write_nvram(__pa(buf), count, off);
                if (rc == OPAL_BUSY_EVENT) {
-                       msleep(OPAL_BUSY_DELAY_MS);
+                       if (in_interrupt() || irqs_disabled())
+                               mdelay(OPAL_BUSY_DELAY_MS);
+                       else
+                               msleep(OPAL_BUSY_DELAY_MS);
                        opal_poll_events(NULL);
                } else if (rc == OPAL_BUSY) {
-                       msleep(OPAL_BUSY_DELAY_MS);
+                       if (in_interrupt() || irqs_disabled())
+                               mdelay(OPAL_BUSY_DELAY_MS);
+                       else
+                               msleep(OPAL_BUSY_DELAY_MS);
                }
        }
 
-- 
2.17.0