tests: serialize bpf-obj_get_info_by_fd based executables

Concurrent execution of many bpf-obj_get_info_by_fd based tests may
lead to a temporary resource shortage that causes them to fail with
the following error diagnostics:

	BPF_MAP_CREATE failed: Operation not permitted

Avoid this issue by serializing execution of all relevant tests.

* tests/lock_file.c: New file.
* tests/Makefile.am (libtests_a_SOURCES): Add lock_file.c
* tests/tests.h (lock_file_by_dirname): New prototype.
* tests/bpf-obj_get_info_by_fd.c (main): Call lock_file_by_dirname
to obtain an exclusive lock on bpf-obj_get_info_by_fd executable.

References: https://github.com/strace/strace/issues/74
References: https://github.com/strace/strace/issues/105

diff --git a/tests/Makefile.am b/tests/Makefile.am
index ab2ae78d03430c72e626bd5e7490c46c731dd779..05aede5d3edee6b7859bb7be4d4f9e7addbaa552 100644 (file)
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -40,6 +40,7 @@ libtests_a_SOURCES = \
        inode_of_sockfd.c \
        libmmsg.c \
        libsocketcall.c \
+       lock_file.c \
        overflowuid.c \
        pipe_maxfd.c \
        print_quoted_string.c \

diff --git a/tests/bpf-obj_get_info_by_fd.c b/tests/bpf-obj_get_info_by_fd.c
index 3e18591d3c300ab995c704ae63520a950e1abe2e..2bbebc30c0d3333163d8848c984dff02e714ac15 100644 (file)
--- a/tests/bpf-obj_get_info_by_fd.c
+++ b/tests/bpf-obj_get_info_by_fd.c
@@ -232,8 +232,10 @@ try_bpf(kernel_ulong_t cmd, void (*printer)(void *attr, size_t size, long rc),
 }
 
 int
-main(void)
+main(int ac, char **av)
 {
+       lock_file_by_dirname(av[0], "bpf-obj_get_info_by_fd");
+
        struct BPF_MAP_CREATE_struct bpf_map_create_attr = {
                .map_type    = BPF_MAP_TYPE_ARRAY,
                .key_size    = 4,

diff --git a/tests/lock_file.c b/tests/lock_file.c
new file mode 100644 (file)
index 0000000..56cf112
--- /dev/null
+++ b/tests/lock_file.c
@@ -0,0 +1,38 @@
+/*
+ * Copyright (c) 2019 The strace developers.
+ * All rights reserved.
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
+#include "tests.h"
+
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <sys/file.h>
+
+/* Obtain an exclusive lock on dirname(path_name)/lock_name file.  */
+int
+lock_file_by_dirname(const char *path_name, const char *lock_name)
+{
+       const char *slash = path_name ? strrchr(path_name, '/') : NULL;
+       const int plen = slash ? (int) (slash - path_name) + 1 : 0;
+
+       char *lock_file = NULL;
+       if (asprintf(&lock_file, "%.*s%s", plen, path_name, lock_name) < 0)
+               perror_msg_and_fail("asprintf");
+
+       int lock_fd = open(lock_file, O_RDONLY);
+       if (lock_fd < 0)
+               perror_msg_and_fail("open: %s", lock_file);
+
+       if (flock(lock_fd, LOCK_EX))
+               perror_msg_and_fail("flock: %s", lock_file);
+
+       free(lock_file);
+
+       return lock_fd;
+}

diff --git a/tests/tests.h b/tests/tests.h
index 4fca98862239c611cf0c68e191a0b99abacffd7c..8403bbb9fea769396332d5a1b393eca5047fc8a7 100644 (file)
--- a/tests/tests.h
+++ b/tests/tests.h
@@ -86,6 +86,12 @@ void perror_msg_and_skip(const char *, ...)
 /* Stat the specified file and skip the test if the stat call failed. */
 void skip_if_unavailable(const char *);
 
+/*
+ * Obtain an exclusive lock on dirname(path_name)/lock_name file
+ * using open and flock.
+ */
+int lock_file_by_dirname(const char *path_name, const char *lock_name);
+
 /*
  * Allocate memory that ends on the page boundary.
  * Pages allocated by this call are preceded by an unmapped page