[PATCH v5] drm/xe: Add helper function to inject fault into ct_dead_capture()

[Satyanarayana K V P]

When injecting fault to xe_guc_ct_send_recv() & xe_guc_mmio_send_recv()
functions, the CI test systems are going out of space and crashing. To
avoid this issue, a new helper function is created and when fault is
injected into this xe_inject_fault() helper function, ct dead capture
is avoided which suppresses ct dumps in the log.

Signed-off-by: Satyanarayana K V P <satyanarayana.k.v.p at intel.com>
Suggested-by: John Harrison <John.C.Harrison at Intel.com>
---
Cc: Michal Wajdeczko <michal.wajdeczko at intel.com>
Cc: Jani Nikula <jani.nikula at intel.com>

V4 -> V5:
- Fixed review comments.

V3 -> V4:
- Updated the name of helper function and moved to xe_device.h file.

V2 -> V3:
- Added inline function to avoid compilation error in the absence of
CONFIG_FUNCTION_ERROR_INJECTION.

V1 -> V2:
- Fixed review comments.
---
 drivers/gpu/drm/xe/xe_device.c | 18 ++++++++++++++++++
 drivers/gpu/drm/xe/xe_device.h | 14 ++++++++++++++
 drivers/gpu/drm/xe/xe_guc_ct.c |  6 ++++++
 3 files changed, 38 insertions(+)

diff --git a/drivers/gpu/drm/xe/xe_device.c b/drivers/gpu/drm/xe/xe_device.c
index 660b0c5126dc..e1b4087a2974 100644
--- a/drivers/gpu/drm/xe/xe_device.c
+++ b/drivers/gpu/drm/xe/xe_device.c
@@ -1120,6 +1120,24 @@ static void xe_device_wedged_fini(struct drm_device *drm, void *arg)
 	xe_pm_runtime_put(xe);
 }
 
+/**
+ * xe_is_injection_active() - Helper function to test whether a fault
+ * inject test is running.
+ *
+ * This is a helper function that the driver can use to detect whether
+ * a fault injection test is running in order to suppress excessive debug
+ * output. By default, the return value is fixed as zero but it can be modified
+ * by the fault injection framework to return an error.
+ *
+ * Returns:
+ * 0 if no fault is injected.
+ * Injected error if fault is injected.
+ */
+int xe_is_injection_active(void)
+{
+	return xe_inject_fault();
+}
+
 /**
  * xe_device_declare_wedged - Declare device wedged
  * @xe: xe device instance
diff --git a/drivers/gpu/drm/xe/xe_device.h b/drivers/gpu/drm/xe/xe_device.h
index 0bc3bc8e6803..13a43fe4fb64 100644
--- a/drivers/gpu/drm/xe/xe_device.h
+++ b/drivers/gpu/drm/xe/xe_device.h
@@ -195,6 +195,20 @@ void xe_device_declare_wedged(struct xe_device *xe);
 struct xe_file *xe_file_get(struct xe_file *xef);
 void xe_file_put(struct xe_file *xef);
 
+#ifdef CONFIG_FUNCTION_ERROR_INJECTION
+/*
+ * As fault is injected using this function, need to make sure that
+ * the compiler does not optimize and make it as a inline function.
+ * To prevent compile optimization, "noinline" is added.
+ */
+static noinline int xe_inject_fault(void) { return 0; }
+ALLOW_ERROR_INJECTION(xe_inject_fault, ERRNO);
+#else
+static inline int xe_inject_fault(void) { return 0; }
+#endif
+
+int xe_is_injection_active(void);
+
 /*
  * Occasionally it is seen that the G2H worker starts running after a delay of more than
  * a second even after being queued and activated by the Linux workqueue subsystem. This
diff --git a/drivers/gpu/drm/xe/xe_guc_ct.c b/drivers/gpu/drm/xe/xe_guc_ct.c
index 822f4c33f730..89f992feba31 100644
--- a/drivers/gpu/drm/xe/xe_guc_ct.c
+++ b/drivers/gpu/drm/xe/xe_guc_ct.c
@@ -2040,6 +2040,12 @@ static void ct_dead_capture(struct xe_guc_ct *ct, struct guc_ctb *ctb, u32 reaso
 
 	if (ctb)
 		ctb->info.broken = true;
+	/*
+	 * Huge dump is getting generated when injecting error for guc CT/MMIO
+	 * functions. So, let us suppress the dump when fault is injected.
+	 */
+	if (xe_is_injection_active())
+		return;
 
 	/* Ignore further errors after the first dump until a reset */
 	if (ct->dead.reported)
-- 
2.34.1