perf dso: Separate generic code in dso_cache__read

Move the file specific code in the dso_cache__read function to a
separate file_read function. I'll add BPF specific code in the following
patches.
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: Stanislav Fomichev <sdf@google.com>
Link: http://lkml.kernel.org/r/20190508132010.14512-3-jolsa@kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/dso.c

@@ -794,21 +794,11 @@ dso_cache__memcpy(struct dso_cache *cache, u64 offset,
 	return cache_size;
 }
 
-static ssize_t
-dso_cache__read(struct dso *dso, struct machine *machine,
-		u64 offset, u8 *data, ssize_t size)
+static ssize_t file_read(struct dso *dso, struct machine *machine,
+			 u64 offset, char *data)
 {
-	struct dso_cache *cache;
-	struct dso_cache *old;
 	ssize_t ret;
 
-	do {
-		u64 cache_offset;
-
-		cache = zalloc(sizeof(*cache) + DSO__DATA_CACHE_SIZE);
-		if (!cache)
-			return -ENOMEM;
-
 	pthread_mutex_lock(&dso__data_open_lock);
 
 	/*
@@ -818,22 +808,38 @@ dso_cache__read(struct dso *dso, struct machine *machine,
 	try_to_open_dso(dso, machine);
 
 	if (dso->data.fd < 0) {
-			ret = -errno;
 		dso->data.status = DSO_DATA_STATUS_ERROR;
-			break;
+		ret = -errno;
+		goto out;
 	}
 
-		cache_offset = offset & DSO__DATA_CACHE_MASK;
+	ret = pread(dso->data.fd, data, DSO__DATA_CACHE_SIZE, offset);
+out:
+	pthread_mutex_unlock(&dso__data_open_lock);
+	return ret;
+}
+
+static ssize_t
+dso_cache__read(struct dso *dso, struct machine *machine,
+		u64 offset, u8 *data, ssize_t size)
+{
+	struct dso_cache *cache;
+	struct dso_cache *old;
+	ssize_t ret;
+
+	do {
+		u64 cache_offset = offset & DSO__DATA_CACHE_MASK;
 
-		ret = pread(dso->data.fd, cache->data, DSO__DATA_CACHE_SIZE, cache_offset);
-		if (ret <= 0)
-			break;
+		cache = zalloc(sizeof(*cache) + DSO__DATA_CACHE_SIZE);
+		if (!cache)
+			return -ENOMEM;
+
+		ret = file_read(dso, machine, cache_offset, cache->data);
 
 		cache->offset = cache_offset;
 		cache->size   = ret;
 	} while (0);
 
-	pthread_mutex_unlock(&dso__data_open_lock);
 
 	if (ret > 0) {
 		old = dso_cache__insert(dso, cache);