ALSA: virtio: Replace zero-length array with flexible-array member

There is a regular need in the kernel to provide a way to declare
having a dynamically sized set of trailing elements in a structure.
Kernel code should always use “flexible array members”[1] for these
cases. The older style of one-element or zero-length arrays should
no longer be used[2].

Also, make use of the struct_size() helper in kzalloc().

[1] https://en.wikipedia.org/wiki/Flexible_array_member
[2] https://www.kernel.org/doc/html/v5.10/process/deprecated.html#zero-length-and-one-element-arrays

Link: https://github.com/KSPP/linux/issues/78
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Link: https://lore.kernel.org/r/20210929191504.GA337268@embeddedor
Signed-off-by: Takashi Iwai <tiwai@suse.de>

diff --git a/sound/virtio/virtio_pcm_msg.c b/sound/virtio/virtio_pcm_msg.c
index f88c8f2..aca2dc1 100644 (file)
--- a/sound/virtio/virtio_pcm_msg.c
+++ b/sound/virtio/virtio_pcm_msg.c
@@ -20,7 +20,7 @@ struct virtio_pcm_msg {
        struct virtio_snd_pcm_xfer xfer;
        struct virtio_snd_pcm_status status;
        size_t length;
-       struct scatterlist sgs[0];
+       struct scatterlist sgs[];
 };
 
 /**
@@ -146,8 +146,7 @@ int virtsnd_pcm_msg_alloc(struct virtio_pcm_substream *vss,
                int sg_num = virtsnd_pcm_sg_num(data, period_bytes);
                struct virtio_pcm_msg *msg;
 
-               msg = kzalloc(sizeof(*msg) + sizeof(*msg->sgs) * (sg_num + 2),
-                             GFP_KERNEL);
+               msg = kzalloc(struct_size(msg, sgs, sg_num + 2), GFP_KERNEL);
                if (!msg)
                        return -ENOMEM;