From 372cf1244d7c271806b83b32b09a1c8b1b31b353 Mon Sep 17 00:00:00 2001 From: Gavin Shan Date: Thu, 24 Apr 2014 18:00:22 +1000 Subject: [PATCH 1/2] powerpc/powernv: Reset root port in firmware Resetting root port has more stuff to do than that for PCIe switch ports and we should have resetting root port done in firmware instead of the kernel itself. The problem was introduced by commit 5b2e198e ("powerpc/powernv: Rework EEH reset"). Cc: linux-stable Signed-off-by: Gavin Shan Signed-off-by: Benjamin Herrenschmidt --- arch/powerpc/platforms/powernv/eeh-ioda.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/arch/powerpc/platforms/powernv/eeh-ioda.c b/arch/powerpc/platforms/powernv/eeh-ioda.c index 253fefe3d1a0..5b51079f3e3b 100644 --- a/arch/powerpc/platforms/powernv/eeh-ioda.c +++ b/arch/powerpc/platforms/powernv/eeh-ioda.c @@ -549,7 +549,8 @@ static int ioda_eeh_reset(struct eeh_pe *pe, int option) ret = ioda_eeh_phb_reset(hose, option); } else { bus = eeh_pe_bus_get(pe); - if (pci_is_root_bus(bus)) + if (pci_is_root_bus(bus) || + pci_is_root_bus(bus->parent)) ret = ioda_eeh_root_reset(hose, option); else ret = ioda_eeh_bridge_reset(hose, bus->self, option); From 8050936caf125fbe54111ba5e696b68a360556ba Mon Sep 17 00:00:00 2001 From: Anton Blanchard Date: Fri, 9 May 2014 17:47:12 +1000 Subject: [PATCH 2/2] powerpc: irq work racing with timer interrupt can result in timer interrupt hang I am seeing an issue where a CPU running perf eventually hangs. Traces show timer interrupts happening every 4 seconds even when a userspace task is running on the CPU. /proc/timer_list also shows pending hrtimers have not run in over an hour, including the scheduler. Looking closer, decrementers_next_tb is getting set to 0xffffffffffffffff, and at that point we will never take a timer interrupt again. In __timer_interrupt() we set decrementers_next_tb to 0xffffffffffffffff and rely on ->event_handler to update it: *next_tb = ~(u64)0; if (evt->event_handler) evt->event_handler(evt); In this case ->event_handler is hrtimer_interrupt. This will eventually call back through the clockevents code with the next event to be programmed: static int decrementer_set_next_event(unsigned long evt, struct clock_event_device *dev) { /* Don't adjust the decrementer if some irq work is pending */ if (test_irq_work_pending()) return 0; __get_cpu_var(decrementers_next_tb) = get_tb_or_rtc() + evt; If irq work came in between these two points, we will return before updating decrementers_next_tb and we never process a timer interrupt again. This looks to have been introduced by 0215f7d8c53f (powerpc: Fix races with irq_work). Fix it by removing the early exit and relying on code later on in the function to force an early decrementer: /* We may have raced with new irq work */ if (test_irq_work_pending()) set_dec(1); Signed-off-by: Anton Blanchard Cc: stable@vger.kernel.org # 3.14+ Signed-off-by: Benjamin Herrenschmidt --- arch/powerpc/kernel/time.c | 3 --- 1 file changed, 3 deletions(-) diff --git a/arch/powerpc/kernel/time.c b/arch/powerpc/kernel/time.c index 122a580f7322..7e711bdcc6da 100644 --- a/arch/powerpc/kernel/time.c +++ b/arch/powerpc/kernel/time.c @@ -813,9 +813,6 @@ static void __init clocksource_init(void) static int decrementer_set_next_event(unsigned long evt, struct clock_event_device *dev) { - /* Don't adjust the decrementer if some irq work is pending */ - if (test_irq_work_pending()) - return 0; __get_cpu_var(decrementers_next_tb) = get_tb_or_rtc() + evt; set_dec(evt);