staging: vchiq: Have vchiq_dump_* functions return an error code

These functions currently modify the struct dump_context passed
to them, and set context->actual to -EFAULT in case of error.
The issue is that this is never returned to the user (except
accidentally when things align so that that happens). So, have
these functions return 0 on success and the appropriate error
code otherwise, and return nonzero errors to the user.

Reviewed-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Marcelo Diop-Gonzalez <marcgonzalez@google.com>
Reviewed-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
Link: https://lore.kernel.org/r/20191120202102.249121-5-marcgonzalez@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

4 files changed, 104 insertions, 52 deletions

diff --git a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_2835_arm.c b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_2835_arm.c
index e568e9e6eb95..ca30bfd52919 100644
--- a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_2835_arm.c
+++ b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_2835_arm.c
@@ -247,15 +247,14 @@ vchiq_complete_bulk(struct vchiq_bulk *bulk)
 			      bulk->actual);
 }
 
-void
-vchiq_dump_platform_state(void *dump_context)
+int vchiq_dump_platform_state(void *dump_context)
 {
 	char buf[80];
 	int len;
 
 	len = snprintf(buf, sizeof(buf),
 		"  Platform: 2835 (VC master)");
-	vchiq_dump(dump_context, buf, len + 1);
+	return vchiq_dump(dump_context, buf, len + 1);
 }
 
 enum vchiq_status
diff --git a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c
index 8f9cfa083264..02148a24818a 100644
--- a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c
+++ b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c
@@ -2072,14 +2072,13 @@ out:
 *
 ***************************************************************************/
 
-void
-vchiq_dump(void *dump_context, const char *str, int len)
+int vchiq_dump(void *dump_context, const char *str, int len)
 {
 	struct dump_context *context = (struct dump_context *)dump_context;
 	int copy_bytes;
 
 	if (context->actual >= context->space)
-		return;
+		return 0;
 
 	if (context->offset > 0) {
 		int skip_bytes = min_t(int, len, context->offset);
@@ -2088,14 +2087,14 @@ vchiq_dump(void *dump_context, const char *str, int len)
 		len -= skip_bytes;
 		context->offset -= skip_bytes;
 		if (context->offset > 0)
-			return;
+			return 0;
 	}
 	copy_bytes = min_t(int, len, context->space - context->actual);
 	if (copy_bytes == 0)
-		return;
+		return 0;
 	if (copy_to_user(context->buf + context->actual, str,
 			 copy_bytes))
-		context->actual = -EFAULT;
+		return -EFAULT;
 	context->actual += copy_bytes;
 	len -= copy_bytes;
 
@@ -2109,8 +2108,9 @@ vchiq_dump(void *dump_context, const char *str, int len)
 
 		if (copy_to_user(context->buf + context->actual - 1,
 				 &cr, 1))
-			context->actual = -EFAULT;
+			return -EFAULT;
 	}
+	return 0;
 }
 
 /****************************************************************************
@@ -2119,8 +2119,7 @@ vchiq_dump(void *dump_context, const char *str, int len)
 *
 ***************************************************************************/
 
-void
-vchiq_dump_platform_instances(void *dump_context)
+int vchiq_dump_platform_instances(void *dump_context)
 {
 	struct vchiq_state *state = vchiq_get_state();
 	char buf[80];
@@ -2145,6 +2144,7 @@ vchiq_dump_platform_instances(void *dump_context)
 	for (i = 0; i < state->unused_service; i++) {
 		struct vchiq_service *service = state->services[i];
 		struct vchiq_instance *instance;
+		int err;
 
 		if (!service || service->base.callback != service_callback)
 			continue;
@@ -2162,9 +2162,12 @@ vchiq_dump_platform_instances(void *dump_context)
 			       instance->completion_remove,
 			       MAX_COMPLETIONS);
 
-		vchiq_dump(dump_context, buf, len + 1);
+		err = vchiq_dump(dump_context, buf, len + 1);
+		if (err)
+			return err;
 		instance->mark = 1;
 	}
+	return 0;
 }
 
 /****************************************************************************
@@ -2173,9 +2176,8 @@ vchiq_dump_platform_instances(void *dump_context)
 *
 ***************************************************************************/
 
-void
-vchiq_dump_platform_service_state(void *dump_context,
-				  struct vchiq_service *service)
+int vchiq_dump_platform_service_state(void *dump_context,
+				      struct vchiq_service *service)
 {
 	struct user_service *user_service =
 			(struct user_service *)service->base.userdata;
@@ -2196,7 +2198,7 @@ vchiq_dump_platform_service_state(void *dump_context,
 				" (dequeue pending)");
 	}
 
-	vchiq_dump(dump_context, buf, len + 1);
+	return vchiq_dump(dump_context, buf, len + 1);
 }
 
 /****************************************************************************
@@ -2210,13 +2212,16 @@ vchiq_read(struct file *file, char __user *buf,
 	size_t count, loff_t *ppos)
 {
 	struct dump_context context;
+	int err;
 
 	context.buf = buf;
 	context.actual = 0;
 	context.space = count;
 	context.offset = *ppos;
 
-	vchiq_dump_state(&context, &g_state);
+	err = vchiq_dump_state(&context, &g_state);
+	if (err)
+		return err;
 
 	*ppos += context.actual;
 
diff --git a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_core.c b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_core.c
index b9d94f6b9bef..76351078affb 100644
--- a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_core.c
+++ b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_core.c
@@ -3298,7 +3298,7 @@ vchiq_set_service_option(unsigned int handle,
 	return status;
 }
 
-static void
+static int
 vchiq_dump_shared_state(void *dump_context, struct vchiq_state *state,
 			struct vchiq_shared_state *shared, const char *label)
 {
@@ -3318,16 +3318,21 @@ vchiq_dump_shared_state(void *dump_context, struct vchiq_state *state,
 	int i;
 	char buf[80];
 	int len;
+	int err;
 
 	len = scnprintf(buf, sizeof(buf),
 		"  %s: slots %d-%d tx_pos=%x recycle=%x",
 		label, shared->slot_first, shared->slot_last,
 		shared->tx_pos, shared->slot_queue_recycle);
-	vchiq_dump(dump_context, buf, len + 1);
+	err = vchiq_dump(dump_context, buf, len + 1);
+	if (err)
+		return err;
 
 	len = scnprintf(buf, sizeof(buf),
 		"    Slots claimed:");
-	vchiq_dump(dump_context, buf, len + 1);
+	err = vchiq_dump(dump_context, buf, len + 1);
+	if (err)
+		return err;
 
 	for (i = shared->slot_first; i <= shared->slot_last; i++) {
 		struct vchiq_slot_info slot_info =
@@ -3336,27 +3341,34 @@ vchiq_dump_shared_state(void *dump_context, struct vchiq_state *state,
 			len = scnprintf(buf, sizeof(buf),
 				"      %d: %d/%d", i, slot_info.use_count,
 				slot_info.release_count);
-			vchiq_dump(dump_context, buf, len + 1);
+			err = vchiq_dump(dump_context, buf, len + 1);
+			if (err)
+				return err;
 		}
 	}
 
 	for (i = 1; i < shared->debug[DEBUG_ENTRIES]; i++) {
 		len = scnprintf(buf, sizeof(buf), "    DEBUG: %s = %d(%x)",
 			debug_names[i], shared->debug[i], shared->debug[i]);
-		vchiq_dump(dump_context, buf, len + 1);
+		err = vchiq_dump(dump_context, buf, len + 1);
+		if (err)
+			return err;
 	}
+	return 0;
 }
 
-void
-vchiq_dump_state(void *dump_context, struct vchiq_state *state)
+int vchiq_dump_state(void *dump_context, struct vchiq_state *state)
 {
 	char buf[80];
 	int len;
 	int i;
+	int err;
 
 	len = scnprintf(buf, sizeof(buf), "State %d: %s", state->id,
 		conn_state_names[state->conn_state]);
-	vchiq_dump(dump_context, buf, len + 1);
+	err = vchiq_dump(dump_context, buf, len + 1);
+	if (err)
+		return err;
 
 	len = scnprintf(buf, sizeof(buf),
 		"  tx_pos=%x(@%pK), rx_pos=%x(@%pK)",
@@ -3364,12 +3376,16 @@ vchiq_dump_state(void *dump_context, struct vchiq_state *state)
 		state->tx_data + (state->local_tx_pos & VCHIQ_SLOT_MASK),
 		state->rx_pos,
 		state->rx_data + (state->rx_pos & VCHIQ_SLOT_MASK));
-	vchiq_dump(dump_context, buf, len + 1);
+	err = vchiq_dump(dump_context, buf, len + 1);
+	if (err)
+		return err;
 
 	len = scnprintf(buf, sizeof(buf),
 		"  Version: %d (min %d)",
 		VCHIQ_VERSION, VCHIQ_VERSION_MIN);
-	vchiq_dump(dump_context, buf, len + 1);
+	err = vchiq_dump(dump_context, buf, len + 1);
+	if (err)
+		return err;
 
 	if (VCHIQ_ENABLE_STATS) {
 		len = scnprintf(buf, sizeof(buf),
@@ -3377,7 +3393,9 @@ vchiq_dump_state(void *dump_context, struct vchiq_state *state)
 			"error_count=%d",
 			state->stats.ctrl_tx_count, state->stats.ctrl_rx_count,
 			state->stats.error_count);
-		vchiq_dump(dump_context, buf, len + 1);
+		err = vchiq_dump(dump_context, buf, len + 1);
+		if (err)
+			return err;
 	}
 
 	len = scnprintf(buf, sizeof(buf),
@@ -3388,30 +3406,49 @@ vchiq_dump_state(void *dump_context, struct vchiq_state *state)
 		state->data_quota - state->data_use_count,
 		state->local->slot_queue_recycle - state->slot_queue_available,
 		state->stats.slot_stalls, state->stats.data_stalls);
-	vchiq_dump(dump_context, buf, len + 1);
-
-	vchiq_dump_platform_state(dump_context);
-
-	vchiq_dump_shared_state(dump_context, state, state->local, "Local");
-	vchiq_dump_shared_state(dump_context, state, state->remote, "Remote");
-
-	vchiq_dump_platform_instances(dump_context);
+	err = vchiq_dump(dump_context, buf, len + 1);
+	if (err)
+		return err;
+
+	err = vchiq_dump_platform_state(dump_context);
+	if (err)
+		return err;
+
+	err = vchiq_dump_shared_state(dump_context,
+				      state,
+				      state->local,
+				      "Local");
+	if (err)
+		return err;
+	err = vchiq_dump_shared_state(dump_context,
+				      state,
+				      state->remote,
+				      "Remote");
+	if (err)
+		return err;
+
+	err = vchiq_dump_platform_instances(dump_context);
+	if (err)
+		return err;
 
 	for (i = 0; i < state->unused_service; i++) {
 		struct vchiq_service *service = find_service_by_port(state, i);
 
 		if (service) {
-			vchiq_dump_service_state(dump_context, service);
+			err = vchiq_dump_service_state(dump_context, service);
 			unlock_service(service);
+			if (err)
+				return err;
 		}
 	}
+	return 0;
 }
 
-void
-vchiq_dump_service_state(void *dump_context, struct vchiq_service *service)
+int vchiq_dump_service_state(void *dump_context, struct vchiq_service *service)
 {
 	char buf[80];
 	int len;
+	int err;
 
 	len = scnprintf(buf, sizeof(buf), "Service %u: %s (ref %u)",
 		service->localport, srvstate_names[service->srvstate],
@@ -3444,7 +3481,9 @@ vchiq_dump_service_state(void *dump_context, struct vchiq_service *service)
 			service_quota->slot_use_count,
 			service_quota->slot_quota);
 
-		vchiq_dump(dump_context, buf, len + 1);
+		err = vchiq_dump(dump_context, buf, len + 1);
+		if (err)
+			return err;
 
 		tx_pending = service->bulk_tx.local_insert -
 			service->bulk_tx.remote_insert;
@@ -3463,7 +3502,9 @@ vchiq_dump_service_state(void *dump_context, struct vchiq_service *service)
 			BULK_INDEX(service->bulk_rx.remove)].size : 0);
 
 		if (VCHIQ_ENABLE_STATS) {
-			vchiq_dump(dump_context, buf, len + 1);
+			err = vchiq_dump(dump_context, buf, len + 1);
+			if (err)
+				return err;
 
 			len = scnprintf(buf, sizeof(buf),
 				"  Ctrl: tx_count=%d, tx_bytes=%llu, "
@@ -3472,7 +3513,9 @@ vchiq_dump_service_state(void *dump_context, struct vchiq_service *service)
 				service->stats.ctrl_tx_bytes,
 				service->stats.ctrl_rx_count,
 				service->stats.ctrl_rx_bytes);
-			vchiq_dump(dump_context, buf, len + 1);
+			err = vchiq_dump(dump_context, buf, len + 1);
+			if (err)
+				return err;
 
 			len = scnprintf(buf, sizeof(buf),
 				"  Bulk: tx_count=%d, tx_bytes=%llu, "
@@ -3481,7 +3524,9 @@ vchiq_dump_service_state(void *dump_context, struct vchiq_service *service)
 				service->stats.bulk_tx_bytes,
 				service->stats.bulk_rx_count,
 				service->stats.bulk_rx_bytes);
-			vchiq_dump(dump_context, buf, len + 1);
+			err = vchiq_dump(dump_context, buf, len + 1);
+			if (err)
+				return err;
 
 			len = scnprintf(buf, sizeof(buf),
 				"  %d quota stalls, %d slot stalls, "
@@ -3494,10 +3539,13 @@ vchiq_dump_service_state(void *dump_context, struct vchiq_service *service)
 		}
 	}
 
-	vchiq_dump(dump_context, buf, len + 1);
+	err = vchiq_dump(dump_context, buf, len + 1);
+	if (err)
+		return err;
 
 	if (service->srvstate != VCHIQ_SRVSTATE_FREE)
-		vchiq_dump_platform_service_state(dump_context, service);
+		err = vchiq_dump_platform_service_state(dump_context, service);
+	return err;
 }
 
 void
diff --git a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_core.h b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_core.h
index 419bcdd165b4..c31f953a9986 100644
--- a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_core.h
+++ b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_core.h
@@ -526,10 +526,10 @@ vchiq_bulk_transfer(unsigned int handle, void *offset, int size,
 		    void *userdata, enum vchiq_bulk_mode mode,
 		    enum vchiq_bulk_dir dir);
 
-extern void
+extern int
 vchiq_dump_state(void *dump_context, struct vchiq_state *state);
 
-extern void
+extern int
 vchiq_dump_service_state(void *dump_context, struct vchiq_service *service);
 
 extern void
@@ -602,16 +602,16 @@ vchiq_platform_resume(struct vchiq_state *state);
 extern void
 vchiq_platform_resumed(struct vchiq_state *state);
 
-extern void
+extern int
 vchiq_dump(void *dump_context, const char *str, int len);
 
-extern void
+extern int
 vchiq_dump_platform_state(void *dump_context);
 
-extern void
+extern int
 vchiq_dump_platform_instances(void *dump_context);
 
-extern void
+extern int
 vchiq_dump_platform_service_state(void *dump_context,
 	struct vchiq_service *service);