accel/qaic: Grab ch_lock during QAIC_ATTACH_SLICE_BO

During QAIC_ATTACH_SLICE_BO, we associate a BO to its DBC. We need to
grab the dbc->ch_lock to make sure that DBC does not goes away while
QAIC_ATTACH_SLICE_BO is still running.

Fixes: ff13be830333 ("accel/qaic: Add datapath")
Signed-off-by: Pranjal Ramajor Asha Kanojiya <quic_pkanojiy@quicinc.com>
Reviewed-by: Carl Vanderlip <quic_carlv@quicinc.com>
Reviewed-by: Jeffrey Hugo <quic_jhugo@quicinc.com>
Signed-off-by: Jeffrey Hugo <quic_jhugo@quicinc.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230517193540.14323-5-quic_jhugo@quicinc.com

diff --git a/drivers/accel/qaic/qaic_data.c b/drivers/accel/qaic/qaic_data.c
index c1af99cfd2d143fcf6f5945a55cdf46c5b2271f9..e42c1f9ffff85eb72650b2bc75590d924d4f3d02 100644 (file)
--- a/drivers/accel/qaic/qaic_data.c
+++ b/drivers/accel/qaic/qaic_data.c
@@ -924,8 +924,8 @@ int qaic_attach_slice_bo_ioctl(struct drm_device *dev, void *data, struct drm_fi
 {
        struct qaic_attach_slice_entry *slice_ent;
        struct qaic_attach_slice *args = data;
+       int rcu_id, usr_rcu_id, qdev_rcu_id;
        struct dma_bridge_chan  *dbc;
-       int usr_rcu_id, qdev_rcu_id;
        struct drm_gem_object *obj;
        struct qaic_device *qdev;
        unsigned long arg_size;
@@ -969,12 +969,6 @@ int qaic_attach_slice_bo_ioctl(struct drm_device *dev, void *data, struct drm_fi
                goto unlock_dev_srcu;
        }
 
-       dbc = &qdev->dbc[args->hdr.dbc_id];
-       if (dbc->usr != usr) {
-               ret = -EINVAL;
-               goto unlock_dev_srcu;
-       }
-
        user_data = u64_to_user_ptr(args->data);
 
        slice_ent = kzalloc(arg_size, GFP_KERNEL);
@@ -1006,9 +1000,16 @@ int qaic_attach_slice_bo_ioctl(struct drm_device *dev, void *data, struct drm_fi
                goto put_bo;
        }
 
+       dbc = &qdev->dbc[args->hdr.dbc_id];
+       rcu_id = srcu_read_lock(&dbc->ch_lock);
+       if (dbc->usr != usr) {
+               ret = -EINVAL;
+               goto unlock_ch_srcu;
+       }
+
        ret = qaic_prepare_bo(qdev, bo, &args->hdr);
        if (ret)
-               goto put_bo;
+               goto unlock_ch_srcu;
 
        ret = qaic_attach_slicing_bo(qdev, bo, &args->hdr, slice_ent);
        if (ret)
@@ -1018,6 +1019,7 @@ int qaic_attach_slice_bo_ioctl(struct drm_device *dev, void *data, struct drm_fi
                dma_sync_sgtable_for_cpu(&qdev->pdev->dev, bo->sgt, args->hdr.dir);
 
        bo->dbc = dbc;
+       srcu_read_unlock(&dbc->ch_lock, rcu_id);
        drm_gem_object_put(obj);
        srcu_read_unlock(&qdev->dev_lock, qdev_rcu_id);
        srcu_read_unlock(&usr->qddev_lock, usr_rcu_id);
@@ -1026,6 +1028,8 @@ int qaic_attach_slice_bo_ioctl(struct drm_device *dev, void *data, struct drm_fi
 
 unprepare_bo:
        qaic_unprepare_bo(qdev, bo);
+unlock_ch_srcu:
+       srcu_read_unlock(&dbc->ch_lock, rcu_id);
 put_bo:
        drm_gem_object_put(obj);
 free_slice_ent: