drm/amdgpu: Use delayed work to collect RAS error counters

On Context Query2 IOCTL return the correctable and
uncorrectable errors in O(1) fashion, from cached
values, and schedule a delayed work function to
calculate and cache them for the next such IOCTL.

v2: Cancel pending delayed work at ras_fini().
v3: Remove conditionals when dealing with delayed
    work manipulation as they're inherently racy.

Cc: Alexander Deucher <Alexander.Deucher@amd.com>
Cc: Christian König <christian.koenig@amd.com>
Cc: John Clements <john.clements@amd.com>
Cc: Hawking Zhang <Hawking.Zhang@amd.com>
Signed-off-by: Luben Tuikov <luben.tuikov@amd.com>
Reviewed-by: Alexander Deucher <Alexander.Deucher@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c

@@ -331,10 +331,13 @@ static int amdgpu_ctx_query(struct amdgpu_device *adev,
 	return 0;
 }
 
+#define AMDGPU_RAS_COUNTE_DELAY_MS 3000
+
 static int amdgpu_ctx_query2(struct amdgpu_device *adev,
 			     struct amdgpu_fpriv *fpriv, uint32_t id,
 			     union drm_amdgpu_ctx_out *out)
 {
+	struct amdgpu_ras *con = amdgpu_ras_get_context(adev);
 	struct amdgpu_ctx *ctx;
 	struct amdgpu_ctx_mgr *mgr;
 
@@ -361,6 +364,30 @@ static int amdgpu_ctx_query2(struct amdgpu_device *adev,
 	if (atomic_read(&ctx->guilty))
 		out->state.flags |= AMDGPU_CTX_QUERY2_FLAGS_GUILTY;
 
+	if (adev->ras_enabled && con) {
+		/* Return the cached values in O(1),
+		 * and schedule delayed work to cache
+		 * new vaues.
+		 */
+		int ce_count, ue_count;
+
+		ce_count = atomic_read(&con->ras_ce_count);
+		ue_count = atomic_read(&con->ras_ue_count);
+
+		if (ce_count != ctx->ras_counter_ce) {
+			ctx->ras_counter_ce = ce_count;
+			out->state.flags |= AMDGPU_CTX_QUERY2_FLAGS_RAS_CE;
+		}
+
+		if (ue_count != ctx->ras_counter_ue) {
+			ctx->ras_counter_ue = ue_count;
+			out->state.flags |= AMDGPU_CTX_QUERY2_FLAGS_RAS_UE;
+		}
+
+		schedule_delayed_work(&con->ras_counte_delay_work,
+				      msecs_to_jiffies(AMDGPU_RAS_COUNTE_DELAY_MS));
+	}
+
 	mutex_unlock(&mgr->lock);
 	return 0;
 }

drivers/gpu/drm/amd/amdgpu/amdgpu_ras.c

@@ -27,6 +27,7 @@
 #include <linux/uaccess.h>
 #include <linux/reboot.h>
 #include <linux/syscalls.h>
+#include <linux/pm_runtime.h>
 
 #include "amdgpu.h"
 #include "amdgpu_ras.h"
@@ -2116,6 +2117,30 @@ static void amdgpu_ras_check_supported(struct amdgpu_device *adev)
 		adev->ras_hw_enabled & amdgpu_ras_mask;
 }
 
+static void amdgpu_ras_counte_dw(struct work_struct *work)
+{
+	struct amdgpu_ras *con = container_of(work, struct amdgpu_ras,
+					      ras_counte_delay_work.work);
+	struct amdgpu_device *adev = con->adev;
+	struct drm_device *dev = &adev->ddev;
+	unsigned long ce_count, ue_count;
+	int res;
+
+	res = pm_runtime_get_sync(dev->dev);
+	if (res < 0)
+		goto Out;
+
+	/* Cache new values.
+	 */
+	amdgpu_ras_query_error_count(adev, &ce_count, &ue_count);
+	atomic_set(&con->ras_ce_count, ce_count);
+	atomic_set(&con->ras_ue_count, ue_count);
+
+	pm_runtime_mark_last_busy(dev->dev);
+Out:
+	pm_runtime_put_autosuspend(dev->dev);
+}
+
 int amdgpu_ras_init(struct amdgpu_device *adev)
 {
 	struct amdgpu_ras *con = amdgpu_ras_get_context(adev);
@@ -2130,6 +2155,11 @@ int amdgpu_ras_init(struct amdgpu_device *adev)
 	if (!con)
 		return -ENOMEM;
 
+	con->adev = adev;
+	INIT_DELAYED_WORK(&con->ras_counte_delay_work, amdgpu_ras_counte_dw);
+	atomic_set(&con->ras_ce_count, 0);
+	atomic_set(&con->ras_ue_count, 0);
+
 	con->objs = (struct ras_manager *)(con + 1);
 
 	amdgpu_ras_set_context(adev, con);
@@ -2233,6 +2263,8 @@ int amdgpu_ras_late_init(struct amdgpu_device *adev,
 			 struct ras_fs_if *fs_info,
 			 struct ras_ih_if *ih_info)
 {
+	struct amdgpu_ras *con = amdgpu_ras_get_context(adev);
+	unsigned long ue_count, ce_count;
 	int r;
 
 	/* disable RAS feature per IP block if it is not supported */
@@ -2273,6 +2305,12 @@ int amdgpu_ras_late_init(struct amdgpu_device *adev,
 	if (r)
 		goto sysfs;
 
+	/* Those are the cached values at init.
+	 */
+	amdgpu_ras_query_error_count(adev, &ce_count, &ue_count);
+	atomic_set(&con->ras_ce_count, ce_count);
+	atomic_set(&con->ras_ue_count, ue_count);
+
 	return 0;
 cleanup:
 	amdgpu_ras_sysfs_remove(adev, ras_block);
@@ -2390,6 +2428,8 @@ int amdgpu_ras_fini(struct amdgpu_device *adev)
 	if (con->features)
 		amdgpu_ras_disable_all_features(adev, 1);
 
+	cancel_delayed_work_sync(&con->ras_counte_delay_work);
+
 	amdgpu_ras_set_context(adev, NULL);
 	kfree(con);
 

drivers/gpu/drm/amd/amdgpu/amdgpu_ras.h

@@ -340,6 +340,11 @@ struct amdgpu_ras {
 
 	/* disable ras error count harvest in recovery */
 	bool disable_ras_err_cnt_harvest;
+
+	/* RAS count errors delayed work */
+	struct delayed_work ras_counte_delay_work;
+	atomic_t ras_ue_count;
+	atomic_t ras_ce_count;
 };
 
 struct ras_fs_data {