[PATCH v3] 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_should_fail_ct_dead_capture() 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>
Tested-by: Aditya Chauhan <aditya.chauhan at intel.com>

---
Cc: Jani Nikula <jani.nikula at intel.com>

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_guc_ct.c | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/drivers/gpu/drm/xe/xe_guc_ct.c b/drivers/gpu/drm/xe/xe_guc_ct.c
index 2447de0ebedf..d959cc2e7b40 100644
--- a/drivers/gpu/drm/xe/xe_guc_ct.c
+++ b/drivers/gpu/drm/xe/xe_guc_ct.c
@@ -1770,6 +1770,24 @@ void xe_guc_ct_print(struct xe_guc_ct *ct, struct drm_printer *p, bool want_ctb)
 }
 
 #if IS_ENABLED(CONFIG_DRM_XE_DEBUG)
+/**
+ * xe_should_fail_ct_dead_capture - Helper function to inject fault.
+ *
+ * This is a helper function to inject fault into ct_dead_capture().
+ * 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.
+ */
+#ifdef CONFIG_FUNCTION_ERROR_INJECTION
+static noinline int xe_should_fail_ct_dead_capture(void)
+{
+	return 0;
+}
+ALLOW_ERROR_INJECTION(xe_should_fail_ct_dead_capture, ERRNO);
+#else
+static inline int xe_should_fail_ct_dead_capture(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;
@@ -1778,6 +1796,13 @@ static void ct_dead_capture(struct xe_guc_ct *ct, struct guc_ctb *ctb, u32 reaso
 	unsigned long flags;
 	bool have_capture;
 
+	/*
+	 * 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_should_fail_ct_dead_capture())
+		return;
+
 	if (ctb)
 		ctb->info.broken = true;
 
-- 
2.43.0