From: Chris Wilson chris@chris-wilson.co.uk
The breadcrumbs use a GT wakeref for guarding the interrupt, but are disarmed during release of the engine wakeref. This leaves a hole where we may attach a breadcrumb just as the engine is parking (after it has parked its breadcrumbs), execute the irq worker with some signalers still attached, but never be woken again.
That issue manifests itself in CI with IGT runner timeouts while tests are waiting indefinitely for release of all GT wakerefs.
<6> [209.151778] i915: Running live_engine_pm_selftests/live_engine_busy_stats <7> [209.231628] i915 0000:00:02.0: [drm:intel_power_well_disable [i915]] disabling PW_5 <7> [209.231816] i915 0000:00:02.0: [drm:intel_power_well_disable [i915]] disabling PW_4 <7> [209.231944] i915 0000:00:02.0: [drm:intel_power_well_disable [i915]] disabling PW_3 <7> [209.232056] i915 0000:00:02.0: [drm:intel_power_well_disable [i915]] disabling PW_2 <7> [209.232166] i915 0000:00:02.0: [drm:intel_power_well_disable [i915]] disabling DC_off <7> [209.232270] i915 0000:00:02.0: [drm:skl_enable_dc6 [i915]] Enabling DC6 <7> [209.232368] i915 0000:00:02.0: [drm:gen9_set_dc_state.part.0 [i915]] Setting DC state from 00 to 02 <4> [299.356116] [IGT] Inactivity timeout exceeded. Killing the current test with SIGQUIT. ... <6> [299.356526] sysrq: Show State ... <6> [299.373964] task:i915_selftest state:D stack:11784 pid:5578 tgid:5578 ppid:873 flags:0x00004002 <6> [299.373967] Call Trace: <6> [299.373968] <TASK> <6> [299.373970] __schedule+0x3bb/0xda0 <6> [299.373974] schedule+0x41/0x110 <6> [299.373976] intel_wakeref_wait_for_idle+0x82/0x100 [i915] <6> [299.374083] ? __pfx_var_wake_function+0x10/0x10 <6> [299.374087] live_engine_busy_stats+0x9b/0x500 [i915] <6> [299.374173] __i915_subtests+0xbe/0x240 [i915] <6> [299.374277] ? __pfx___intel_gt_live_setup+0x10/0x10 [i915] <6> [299.374369] ? __pfx___intel_gt_live_teardown+0x10/0x10 [i915] <6> [299.374456] intel_engine_live_selftests+0x1c/0x30 [i915] <6> [299.374547] __run_selftests+0xbb/0x190 [i915] <6> [299.374635] i915_live_selftests+0x4b/0x90 [i915] <6> [299.374717] i915_pci_probe+0x10d/0x210 [i915]
At the end of the interrupt worker, if there are no more engines awake, disarm the breadcrumb and go to sleep.
Fixes: 9d5612ca165a ("drm/i915/gt: Defer enabling the breadcrumb interrupt to after submission") Closes: https://gitlab.freedesktop.org/drm/intel/issues/10026 Signed-off-by: Chris Wilson chris@chris-wilson.co.uk Cc: Andrzej Hajda andrzej.hajda@intel.com Cc: stable@vger.kernel.org # v5.12+ Signed-off-by: Janusz Krzysztofik janusz.krzysztofik@linux.intel.com Acked-by: Nirmoy Das nirmoy.das@intel.com Reviewed-by: Andrzej Hajda andrzej.hajda@intel.com Reviewed-by: Andi Shyti andi.shyti@linux.intel.com Signed-off-by: Andi Shyti andi.shyti@linux.intel.com Link: https://patchwork.freedesktop.org/patch/msgid/20240423165505.465734-2-janusz... (cherry picked from commit fbad43eccae5cb14594195c20113369aabaa22b5) Signed-off-by: Jani Nikula jani.nikula@intel.com (cherry picked from commit 70cb9188ffc75e643debf292fcddff36c9dbd4ae) Signed-off-by: Janusz Krzysztofik janusz.krzysztofik@linux.intel.com --- drivers/gpu/drm/i915/gt/intel_breadcrumbs.c | 13 ++++++------- 1 file changed, 6 insertions(+), 7 deletions(-)
diff --git a/drivers/gpu/drm/i915/gt/intel_breadcrumbs.c b/drivers/gpu/drm/i915/gt/intel_breadcrumbs.c index 209cf265bf746..ad8c0a4f4a31f 100644 --- a/drivers/gpu/drm/i915/gt/intel_breadcrumbs.c +++ b/drivers/gpu/drm/i915/gt/intel_breadcrumbs.c @@ -257,8 +257,13 @@ static void signal_irq_work(struct irq_work *work) i915_request_put(rq); }
+ /* Lazy irq enabling after HW submission */ if (!READ_ONCE(b->irq_armed) && !list_empty(&b->signalers)) intel_breadcrumbs_arm_irq(b); + + /* And confirm that we still want irqs enabled before we yield */ + if (READ_ONCE(b->irq_armed) && !atomic_read(&b->active)) + intel_breadcrumbs_disarm_irq(b); }
struct intel_breadcrumbs * @@ -309,13 +314,7 @@ void __intel_breadcrumbs_park(struct intel_breadcrumbs *b) return;
/* Kick the work once more to drain the signalers, and disarm the irq */ - irq_work_sync(&b->irq_work); - while (READ_ONCE(b->irq_armed) && !atomic_read(&b->active)) { - local_irq_disable(); - signal_irq_work(&b->irq_work); - local_irq_enable(); - cond_resched(); - } + irq_work_queue(&b->irq_work); }
void intel_breadcrumbs_free(struct kref *kref)