greybus: core: avoid I/O to disconnected interfaces

Add new helper to disable connections to interfaces that have already
been disconnected (e.g. forcibly removed).

The connection tear-down procedure differs enough depending on whether
the interface is still present or already gone to warrant a dedicated
helper. This will become more obvious with the new tear-down procedure,
which involves I/O on the connection being tore down.

This also simplifies handling of the legacy bootrom, which does not
support the new tear-down operations.

Specifically, this allows us to remove the early control-connection
tear down during interface disable, and also avoids some error messages
currently printed during legacy mode switch (i.e. bootrom
boot-over-UniPro) and forcible removal.

Reviewed-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Johan Hovold <johan@hovoldconsulting.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>

1 files changed, 21 insertions, 0 deletions

diff --git a/drivers/staging/greybus/connection.c b/drivers/staging/greybus/connection.c
index ac3be2fceade..7e07ef832b7c 100644
--- a/drivers/staging/greybus/connection.c
+++ b/drivers/staging/greybus/connection.c
@@ -654,6 +654,27 @@ out_unlock:
 }
 EXPORT_SYMBOL_GPL(gb_connection_disable);
 
+/* Disable a connection without communicating with the remote end. */
+void gb_connection_disable_forced(struct gb_connection *connection)
+{
+	mutex_lock(&connection->mutex);
+
+	if (connection->state == GB_CONNECTION_STATE_DISABLED)
+		goto out_unlock;
+
+	spin_lock_irq(&connection->lock);
+	connection->state = GB_CONNECTION_STATE_DISABLED;
+	gb_connection_cancel_operations(connection, -ESHUTDOWN);
+	spin_unlock_irq(&connection->lock);
+
+	gb_connection_svc_connection_destroy(connection);
+	gb_connection_hd_cport_disable(connection);
+
+out_unlock:
+	mutex_unlock(&connection->mutex);
+}
+EXPORT_SYMBOL_GPL(gb_connection_disable_forced);
+
 /* Caller must have disabled the connection before destroying it. */
 void gb_connection_destroy(struct gb_connection *connection)
 {