selftests/bpf: fix a clang compilation error

When building selftests/bpf with clang
  make -j LLVM=1
  make -C tools/testing/selftests/bpf -j LLVM=1
I hit the following compilation error:

  trace_helpers.c:152:9: error: variable 'found' is used uninitialized whenever 'while' loop exits because its condition is false [-Werror,-Wsometimes-uninitialized]
          while (fscanf(f, "%zx-%zx %s %zx %*[^\n]\n", &start, &end, buf, &base) == 4) {
                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  trace_helpers.c:161:7: note: uninitialized use occurs here
          if (!found)
               ^~~~~
  trace_helpers.c:152:9: note: remove the condition if it is always true
          while (fscanf(f, "%zx-%zx %s %zx %*[^\n]\n", &start, &end, buf, &base) == 4) {
                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
                 1
  trace_helpers.c:145:12: note: initialize the variable 'found' to silence this warning
          bool found;
                    ^
                     = false

It is possible that for sane /proc/self/maps we may never hit the above issue
in practice. But let us initialize variable 'found' properly to silence the
compilation error.

Signed-off-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/r/20220127163726.1442032-1-yhs@fb.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

diff --git a/tools/testing/selftests/bpf/trace_helpers.c b/tools/testing/selftests/bpf/trace_helpers.c
index 65ab533..ca6abae 100644 (file)
--- a/tools/testing/selftests/bpf/trace_helpers.c
+++ b/tools/testing/selftests/bpf/trace_helpers.c
@@ -142,7 +142,7 @@ ssize_t get_uprobe_offset(const void *addr)
 {
        size_t start, end, base;
        char buf[256];
-       bool found;
+       bool found = false;
        FILE *f;
 
        f = fopen("/proc/self/maps", "r");