Hi Lee, I'm really sorry for the late reply, I had some holidays in between. On Tue, Jul 04, 2023 at 04:07:27PM +0800, Lee Shawn C wrote: > Perform reboot stresss test on a kernel build with lockdebug flag enabled. > Bad unlock balanace detected would happened sometimes. Below is the > problematic scenario. If params.mmio_debug value was changed at step #4. > And it would trigger this issue. Modify code flow that decide to > enable/disable mmio debug before unclaimed_reg_debug() can avoid > this symptom. > > 1. GEN6_READ_HEADER is called with params.mmio_debug = 0 > 2. unclaimed_reg_debug(before = true) is called > 3. unclaimed_reg_debug return without taking a lock > because params.mmio_debug == 0 > 4. other thread modifies params.mmio_debug to 1 > 5. GEN6_READ_FOOTER is called with params.mmio_debug != 0 > 6. unclaimed_reg_debug tries to assert non-taken lock (first WARN) > 7. unclaimed_reg_debug tries to release non-taken lock (second WARN) > > Closes:https://gitlab.freedesktop.org/drm/intel/-/issues/8749 > Signed-off-by: Lee Shawn C <shawn.c.lee@xxxxxxxxx> > Cc: Uma Shankar <uma.shankar@xxxxxxxxx> > Cc: Matt Roper <matthew.d.roper@xxxxxxxxx> > Cc: Andi Shyti <andi.shyti@xxxxxxxxxxxxxxx> > --- > drivers/gpu/drm/i915/intel_uncore.c | 10 +++++----- > 1 file changed, 5 insertions(+), 5 deletions(-) > > diff --git a/drivers/gpu/drm/i915/intel_uncore.c b/drivers/gpu/drm/i915/intel_uncore.c > index 796ebfe6c550..9d665978cc43 100644 > --- a/drivers/gpu/drm/i915/intel_uncore.c > +++ b/drivers/gpu/drm/i915/intel_uncore.c > @@ -1931,9 +1931,6 @@ unclaimed_reg_debug(struct intel_uncore *uncore, > const bool read, > const bool before) > { > - if (likely(!uncore->i915->params.mmio_debug) || !uncore->debug) > - return; > - this is a very good catch! I'm fine with the change from my side: Reviewed-by: Andi Shyti <andi.shyti@xxxxxxxxxxxxxxx> But I'd like to hear from someone else, as well, Matt, Daniele? Thank you, Andi
