Re: [PATCH][next] scsi: aacraid: Replace one-element array with flexible-array member

[Martin K. Petersen]

Gustavo,

> Precisely this sort of confusion is one of the things we want to avoid
> by using flexible-array members instead of one-element arrays.

Ah, you're right!

Now that I look at it again I also don't think that was the issue that
originally caused concern.

@@ -4020,7 +4020,8 @@ static int aac_convert_sgraw2(struct aac_raw_io2 *rio2, int pages, int nseg, int
 		}
 	}
 	sge[pos] = rio2->sge[nseg-1];
-	memcpy(&rio2->sge[1], &sge[1], (nseg_new-1)*sizeof(struct sge_ieee1212));
+	memcpy(&rio2->sge[1], &sge[1],
+	       flex_array_size(rio2, sge, nseg_new - 1));
 
 	kfree(sge);
 	rio2->sgeCnt = cpu_to_le32(nseg_new);

I find it counter-intuitive to use the type of the destination array to
size the amount of source data to copy. "Are source and destination same
type? Does flex_array_size() do the right thing given the ->sge[1]
destination offset?". It wasn't immediately obvious. To me, "copy this
many scatterlist entries" in the original is much more readable.

That said, this whole function makes my head hurt!

-- 
Martin K. Petersen	Oracle Linux Engineering