4.4-stable review patch. If anyone has any objections, please let me know.
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From: Nicholas Piggin npiggin@gmail.com
commit 3b8070335f751aac9f1526ae2e012e6f5b8b0f21 upstream.
The OPAL NVRAM driver does not sleep in case it gets OPAL_BUSY or OPAL_BUSY_EVENT from firmware, which causes large scheduling latencies, and various lockup errors to trigger (again, BMC reboot can cause it).
Fix this by converting it to the standard form OPAL_BUSY loop that sleeps.
Fixes: 628daa8d5abf ("powerpc/powernv: Add RTC and NVRAM support plus RTAS fallbacks") Depends-on: 34dd25de9fe3 ("powerpc/powernv: define a standard delay for OPAL_BUSY type retry loops") Cc: stable@vger.kernel.org # v3.2+ Signed-off-by: Nicholas Piggin npiggin@gmail.com Signed-off-by: Michael Ellerman mpe@ellerman.id.au Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- arch/powerpc/platforms/powernv/opal-nvram.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-)
--- a/arch/powerpc/platforms/powernv/opal-nvram.c +++ b/arch/powerpc/platforms/powernv/opal-nvram.c @@ -11,6 +11,7 @@
#define DEBUG
+#include <linux/delay.h> #include <linux/kernel.h> #include <linux/init.h> #include <linux/of.h> @@ -56,8 +57,12 @@ static ssize_t opal_nvram_write(char *bu
while (rc == OPAL_BUSY || rc == OPAL_BUSY_EVENT) { rc = opal_write_nvram(__pa(buf), count, off); - if (rc == OPAL_BUSY_EVENT) + if (rc == OPAL_BUSY_EVENT) { + msleep(OPAL_BUSY_DELAY_MS); opal_poll_events(NULL); + } else if (rc == OPAL_BUSY) { + msleep(OPAL_BUSY_DELAY_MS); + } }
if (rc)