perf dso: Simplify dso_cache__read function

There's no need for the while loop now, also we can connect two (ret >
0) condition legs together.
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Acked-by: Song Liu <songliubraving@fb.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Song Liu <songliubraving@fb.com>
Cc: Stanislav Fomichev <sdf@google.com>
Link: http://lkml.kernel.org/r/20190508132010.14512-4-jolsa@kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/dso.c

@@ -823,25 +823,20 @@ static ssize_t
 dso_cache__read(struct dso *dso, struct machine *machine,
 		u64 offset, u8 *data, ssize_t size)
 {
+	u64 cache_offset = offset & DSO__DATA_CACHE_MASK;
 	struct dso_cache *cache;
 	struct dso_cache *old;
 	ssize_t ret;
 
-	do {
-		u64 cache_offset = offset & DSO__DATA_CACHE_MASK;
-
-		cache = zalloc(sizeof(*cache) + DSO__DATA_CACHE_SIZE);
-		if (!cache)
-			return -ENOMEM;
-
-		ret = file_read(dso, machine, cache_offset, cache->data);
+	cache = zalloc(sizeof(*cache) + DSO__DATA_CACHE_SIZE);
+	if (!cache)
+		return -ENOMEM;
 
+	ret = file_read(dso, machine, cache_offset, cache->data);
+	if (ret > 0) {
 		cache->offset = cache_offset;
 		cache->size   = ret;
-	} while (0);
-
 
-	if (ret > 0) {
 		old = dso_cache__insert(dso, cache);
 		if (old) {
 			/* we lose the race */