[PATCH v8] 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_is_injection_active() 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>
Reviewed-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>

---
V7 -> V8;
- Moved xe_is_injection_active() definition to .c file and declaration to .h
  file.

V6 -> V7:
- Moved the xe_is_injection_active() function from .h file to .c file as
compiler is optimizing static function defined in header file into inline
function which is not injecting fault into helper function.

V5 -> V6:
- Fixed review comments.
- Updated helper function description.

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.h |  2 ++
 drivers/gpu/drm/xe/xe_guc_ct.c | 24 ++++++++++++++++++++++++
 2 files changed, 26 insertions(+)

diff --git a/drivers/gpu/drm/xe/xe_device.h b/drivers/gpu/drm/xe/xe_device.h
index 0bc3bc8e6803..e4da797a984b 100644
--- a/drivers/gpu/drm/xe/xe_device.h
+++ b/drivers/gpu/drm/xe/xe_device.h
@@ -195,6 +195,8 @@ 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);
 
+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..d3ec18687139 100644
--- a/drivers/gpu/drm/xe/xe_guc_ct.c
+++ b/drivers/gpu/drm/xe/xe_guc_ct.c
@@ -2030,6 +2030,24 @@ void xe_guc_ct_print(struct xe_guc_ct *ct, struct drm_printer *p, bool want_ctb)
 }
 
 #if IS_ENABLED(CONFIG_DRM_XE_DEBUG)
+
+#ifdef CONFIG_FUNCTION_ERROR_INJECTION
+/*
+ * This is a helper function which assists the driver in identifying if a fault
+ * injection test is currently active, allowing it to reduce unnecessary debug
+ * output. Typically, the function returns zero, but the fault injection
+ * framework can alter this to return an error. Since faults are injected
+ * through this function, it's important to ensure the compiler doesn't optimize
+ * it into an inline function. To avoid such optimization, the 'noinline'
+ * attribute is applied. Compiler optimizes the static function defined in the
+ * header file as an inline function.
+ */
+noinline int xe_is_injection_active(void) { return 0; }
+ALLOW_ERROR_INJECTION(xe_is_injection_active, ERRNO);
+#else
+int xe_is_injection_active(void) { return 0; }
+#endif
+
 static void ct_dead_capture(struct xe_guc_ct *ct, struct guc_ctb *ctb, u32 reason_code)
 {
 	struct xe_guc_log_snapshot *snapshot_log;
@@ -2040,6 +2058,12 @@ 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)
-- 
2.43.0