drm/amdgpu: add mutex lock for cper ring

Avoid the confliction between read and write of ring buffer.

Signed-off-by: Tao Zhou <[email protected]>
Reviewed-by: Hawking Zhang <[email protected]>
Signed-off-by: Alex Deucher <[email protected]>

Author: Tao Zhou

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

@@ -440,6 +440,7 @@ void amdgpu_cper_ring_write(struct amdgpu_ring *ring,
 
 	wptr_old = ring->wptr;
 
+	mutex_lock(&ring->adev->cper.ring_lock);
 	while (count) {
 		ent_sz = amdgpu_cper_ring_get_ent_sz(ring, ring->wptr);
 		chunk = umin(ent_sz, count);
@@ -468,6 +469,7 @@ void amdgpu_cper_ring_write(struct amdgpu_ring *ring,
 			pos = rptr;
 		} while (!amdgpu_cper_is_hdr(ring, rptr));
 	}
+	mutex_unlock(&ring->adev->cper.ring_lock);
 
 	if (ring->count_dw >= (count >> 2))
 		ring->count_dw -= (count >> 2);
@@ -497,6 +499,8 @@ static int amdgpu_cper_ring_init(struct amdgpu_device *adev)
 {
 	struct amdgpu_ring *ring = &(adev->cper.ring_buf);
 
+	mutex_init(&adev->cper.ring_lock);
+
 	ring->adev = NULL;
 	ring->ring_obj = NULL;
 	ring->use_doorbell = false;

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

@@ -64,6 +64,7 @@ struct amdgpu_cper {
 
 	void *ring[CPER_MAX_ALLOWED_COUNT];
 	struct amdgpu_ring ring_buf;
+	struct mutex ring_lock;
 };
 
 void amdgpu_cper_entry_fill_hdr(struct amdgpu_device *adev,

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

@@ -510,13 +510,18 @@ static ssize_t amdgpu_debugfs_ring_read(struct file *f, char __user *buf,
 	result = 0;
 
 	if (*pos < 12) {
+		if (ring->funcs->type == AMDGPU_RING_TYPE_CPER)
+			mutex_lock(&ring->adev->cper.ring_lock);
+
 		early[0] = amdgpu_ring_get_rptr(ring) & ring->buf_mask;
 		early[1] = amdgpu_ring_get_wptr(ring) & ring->buf_mask;
 		early[2] = ring->wptr & ring->buf_mask;
 		for (i = *pos / 4; i < 3 && size; i++) {
 			r = put_user(early[i], (uint32_t *)buf);
-			if (r)
-				return r;
+			if (r) {
+				result = r;
+				goto out;
+			}
 			buf += 4;
 			result += 4;
 			size -= 4;
@@ -547,12 +552,14 @@ static ssize_t amdgpu_debugfs_ring_read(struct file *f, char __user *buf,
 
 		while (size) {
 			if (p == early[1])
-				return result;
+				goto out;
 
 			value = ring->ring[p];
 			r = put_user(value, (uint32_t *)buf);
-			if (r)
-				return r;
+			if (r) {
+				result = r;
+				goto out;
+			}
 
 			buf += 4;
 			result += 4;
@@ -562,6 +569,10 @@ static ssize_t amdgpu_debugfs_ring_read(struct file *f, char __user *buf,
 		}
 	}
 
+out:
+	if (ring->funcs->type == AMDGPU_RING_TYPE_CPER)
+		mutex_unlock(&ring->adev->cper.ring_lock);
+
 	return result;
 }