[PATCH v2 34/47] perf ftrace: Silence -Wshorten-64-to-32 warnings

[Ian Rogers <irogers@google.com>]

The clang warning -Wshorten-64-to-32 can be useful to catch
inadvertent truncation. In some instances this truncation can lead to
changing the sign of a result, for example, truncation to return an
int to fit a sort routine. Silence the warning by making the implicit
truncation explicit.

Signed-off-by: Ian Rogers <irogers@google.com>
---
 tools/perf/builtin-ftrace.c  | 17 +++++++++++------
 tools/perf/util/bpf_ftrace.c |  4 ++--
 2 files changed, 13 insertions(+), 8 deletions(-)

diff --git a/tools/perf/builtin-ftrace.c b/tools/perf/builtin-ftrace.c
index 7caa18d5ffc3..1484d798de40 100644
--- a/tools/perf/builtin-ftrace.c
+++ b/tools/perf/builtin-ftrace.c
@@ -182,7 +182,8 @@ static int read_tracing_file_to_stdout(const char *name)
 
 	/* read contents to stdout */
 	while (true) {
-		int n = read(fd, buf, sizeof(buf));
+		ssize_t n = read(fd, buf, sizeof(buf));
+
 		if (n == 0)
 			break;
 		else if (n < 0)
@@ -449,7 +450,7 @@ static int set_tracing_percpu_buffer_size(struct perf_ftrace *ftrace)
 		return 0;
 
 	ret = write_tracing_file_int("buffer_size_kb",
-				     ftrace->percpu_buffer_size / 1024);
+				     (int)(ftrace->percpu_buffer_size / 1024));
 	if (ret < 0)
 		return ret;
 
@@ -691,7 +692,8 @@ static int __cmd_ftrace(struct perf_ftrace *ftrace)
 			break;
 
 		if (pollfd.revents & POLLIN) {
-			int n = read(trace_fd, buf, sizeof(buf));
+			ssize_t n = read(trace_fd, buf, sizeof(buf));
+
 			if (n < 0)
 				break;
 			if (fwrite(buf, n, 1, stdout) != 1)
@@ -713,7 +715,8 @@ static int __cmd_ftrace(struct perf_ftrace *ftrace)
 
 	/* read remaining buffer contents */
 	while (true) {
-		int n = read(trace_fd, buf, sizeof(buf));
+		ssize_t n = read(trace_fd, buf, sizeof(buf));
+
 		if (n <= 0)
 			break;
 		if (fwrite(buf, n, 1, stdout) != 1)
@@ -1031,7 +1034,8 @@ static int __cmd_latency(struct perf_ftrace *ftrace)
 			break;
 
 		if (pollfd.revents & POLLIN) {
-			int n = read(trace_fd, buf, sizeof(buf) - 1);
+			ssize_t n = read(trace_fd, buf, sizeof(buf) - 1);
+
 			if (n < 0)
 				break;
 
@@ -1049,7 +1053,8 @@ static int __cmd_latency(struct perf_ftrace *ftrace)
 
 	/* read remaining buffer contents */
 	while (!ftrace->target.use_bpf) {
-		int n = read(trace_fd, buf, sizeof(buf) - 1);
+		ssize_t n = read(trace_fd, buf, sizeof(buf) - 1);
+
 		if (n <= 0)
 			break;
 		make_histogram(ftrace, buckets, buf, n, line);
diff --git a/tools/perf/util/bpf_ftrace.c b/tools/perf/util/bpf_ftrace.c
index 7324668cc83e..c4b3bb4e5922 100644
--- a/tools/perf/util/bpf_ftrace.c
+++ b/tools/perf/util/bpf_ftrace.c
@@ -97,7 +97,7 @@ int perf_ftrace__latency_prepare_bpf(struct perf_ftrace *ftrace)
 							    false, func->name);
 	if (IS_ERR(skel->links.func_begin)) {
 		pr_err("Failed to attach fentry program\n");
-		err = PTR_ERR(skel->links.func_begin);
+		err = (int)PTR_ERR(skel->links.func_begin);
 		goto out;
 	}
 
@@ -105,7 +105,7 @@ int perf_ftrace__latency_prepare_bpf(struct perf_ftrace *ftrace)
 							  true, func->name);
 	if (IS_ERR(skel->links.func_end)) {
 		pr_err("Failed to attach fexit program\n");
-		err = PTR_ERR(skel->links.func_end);
+		err = (int)PTR_ERR(skel->links.func_end);
 		goto out;
 	}
 
-- 
2.49.0.906.g1f30a19c02-goog