greybus: core: add lower-limit for host-device buffers

Make sure we never end up with a host device with maximum buffer size
smaller than the shortest Greybus message.

Signed-off-by: Johan Hovold <johan@hovoldconsulting.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>

diff --git a/drivers/staging/greybus/core.c b/drivers/staging/greybus/core.c
index e32d6c4..91dcc5b 100644 (file)
--- a/drivers/staging/greybus/core.c
+++ b/drivers/staging/greybus/core.c
@@ -188,6 +188,11 @@ struct greybus_host_device *greybus_create_hd(struct greybus_host_driver *driver
                return NULL;
        }
 
+       if (buffer_size_max < GB_OPERATION_MESSAGE_SIZE_MIN) {
+               dev_err(parent, "greybus host-device buffers too small\n");
+               return NULL;
+       }
+
        /*
         * Make sure to never allocate messages larger than what the Greybus
         * protocol supports.

diff --git a/drivers/staging/greybus/operation.h b/drivers/staging/greybus/operation.h
index 1edd512..740aacc 100644 (file)
--- a/drivers/staging/greybus/operation.h
+++ b/drivers/staging/greybus/operation.h
@@ -69,6 +69,7 @@ struct gb_operation_msg_hdr {
        __u8    pad[2];         /* must be zero (ignore when read) */
 } __aligned(sizeof(u64));
 
+#define GB_OPERATION_MESSAGE_SIZE_MIN  sizeof(struct gb_operation_msg_hdr)
 #define GB_OPERATION_MESSAGE_SIZE_MAX  U16_MAX
 
 /*