remoteproc: core: Task sync during rproc_fw_boot()

By default, rproc_fw_boot() needs to wait for rproc to be configured,
but a race may occur when using rpmsg/virtio.  In this case, it can
be called locally in a safe manor.

This patch represents two usecases:

 - External call (via exported rproc_boot()), which waits
 - Internal call can use 'nowait' version of rproc_boot()
Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>

drivers/remoteproc/remoteproc_core.c

@@ -1030,8 +1030,9 @@ static void rproc_crash_handler_work(struct work_struct *work)
 }
 
 /**
- * rproc_boot() - boot a remote processor
+ * __rproc_boot() - boot a remote processor
  * @rproc: handle of a remote processor
+ * @wait: wait for rproc registration completion
  *
  * Boot a remote processor (i.e. load its firmware, power it on, ...).
  *
@@ -1040,7 +1041,7 @@ static void rproc_crash_handler_work(struct work_struct *work)
  *
  * Returns 0 on success, and an appropriate error value otherwise.
  */
-int rproc_boot(struct rproc *rproc)
+static int __rproc_boot(struct rproc *rproc, bool wait)
 {
 	const struct firmware *firmware_p;
 	struct device *dev;
@@ -1088,6 +1089,10 @@ int rproc_boot(struct rproc *rproc)
 		goto downref_rproc;
 	}
 
+	/* if rproc virtio is not yet configured, wait */
+	if (wait)
+		wait_for_completion(&rproc->firmware_loading_complete);
+
 	ret = rproc_fw_boot(rproc, firmware_p);
 
 	release_firmware(firmware_p);
@@ -1101,8 +1106,28 @@ int rproc_boot(struct rproc *rproc)
 	mutex_unlock(&rproc->lock);
 	return ret;
 }
+
+/**
+ * rproc_boot() - boot a remote processor
+ * @rproc: handle of a remote processor
+ */
+int rproc_boot(struct rproc *rproc)
+{
+	return __rproc_boot(rproc, true);
+}
 EXPORT_SYMBOL(rproc_boot);
 
+/**
+ * rproc_boot_nowait() - boot a remote processor
+ * @rproc: handle of a remote processor
+ *
+ * Same as rproc_boot() but don't wait for rproc registration completion
+ */
+int rproc_boot_nowait(struct rproc *rproc)
+{
+	return __rproc_boot(rproc, false);
+}
+
 /**
  * rproc_shutdown() - power off the remote processor
  * @rproc: the remote processor

drivers/remoteproc/remoteproc_internal.h

@@ -48,6 +48,7 @@ struct rproc_fw_ops {
 /* from remoteproc_core.c */
 void rproc_release(struct kref *kref);
 irqreturn_t rproc_vq_interrupt(struct rproc *rproc, int vq_id);
+int rproc_boot_nowait(struct rproc *rproc);
 
 /* from remoteproc_virtio.c */
 int rproc_add_virtio_dev(struct rproc_vdev *rvdev, int id);

drivers/remoteproc/remoteproc_virtio.c

@@ -161,7 +161,7 @@ static int rproc_virtio_find_vqs(struct virtio_device *vdev, unsigned nvqs,
 	}
 
 	/* now that the vqs are all set, boot the remote processor */
-	ret = rproc_boot(rproc);
+	ret = rproc_boot_nowait(rproc);
 	if (ret) {
 		dev_err(&rproc->dev, "rproc_boot() failed %d\n", ret);
 		goto error;