[LTP] [RFC PATCH] tst_get_unused_pid and system_specific_process_info

* [LTP] [RFC PATCH] tst_get_unused_pid and system_specific_process_info
@ 2014-06-25 10:00 Stanislav Kholmanskikh
  2014-06-25 12:14 ` chrubis
  0 siblings, 1 reply; 3+ messages in thread
From: Stanislav Kholmanskikh @ 2014-06-25 10:00 UTC (permalink / raw)
  To: ltp-list; +Cc: vasily.isaenko

Hi!

1. We remove get_max_pids(), because it's used only in one place (get_free_pids())
   and can be subsituted with
   SAFE_FILE_SCANF(cleanup_fn, PID_MAX_PATH, "%d", &pid);

2. We rename get_free_pids() to tst_get_free_pids() for consistency. And changing a bit its
   declaration to use SAFE_FILE_SCANF().

3. system_specific_process_info.h is used only in one place - msgctl11.
   I think it's not a problem if I move its content to test.h. For consistency.

4. And add tst_get_unused_pid() to system_specific_process_info.c. To not
   create a new source file. And this funcion looks logically coupled with tst_get_free_pids().

I'm going to present pp. 1-3 in one patch, and p. 4 - in a separate patch.

What do you think about the general idea?

Thanks.

Signed-off-by: Stanislav Kholmanskikh <stanislav.kholmanskikh@oracle.com>
---
 include/system_specific_process_info.h          |   29 -------------
 include/test.h                                  |   15 +++++++
 lib/system_specific_process_info.c              |   49 ++++++----------------
 testcases/kernel/syscalls/ipc/msgctl/msgctl11.c |    3 +-
 4 files changed, 30 insertions(+), 66 deletions(-)
 delete mode 100644 include/system_specific_process_info.h

diff --git a/include/system_specific_process_info.h b/include/system_specific_process_info.h
deleted file mode 100644
index ba8cc9d..0000000
--- a/include/system_specific_process_info.h
+++ /dev/null
@@ -1,29 +0,0 @@
-/*
- *
- *   Copyright (c) International Business Machines  Corp., 2009
- *
- *   This program is free software;  you can redistribute it and/or modify
- *   it under the terms of the GNU General Public License as published by
- *   the Free Software Foundation; either version 2 of the License, or
- *   (at your option) any later version.
- *
- *   This program is distributed in the hope that it will be useful,
- *   but WITHOUT ANY WARRANTY;  without even the implied warranty of
- *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See
- *   the GNU General Public License for more details.
- *
- *   You should have received a copy of the GNU General Public License
- *   along with this program;  if not, write to the Free Software
- *   Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
- */
-
-#ifndef _SYS_SPECIFIC_PROCESS_INFO_H_
-#define _SYS_SPECIFIC_PROCESS_INFO_H_
-
-/* Returns max pid count obtained from reading /proc/sys/kernel/pid_max */
-int get_max_pids(void);
-
-/* Returns number of free pids */
-int get_free_pids(void);
-
-#endif
diff --git a/include/test.h b/include/test.h
index 97ce0f0..bf6deed 100644
--- a/include/test.h
+++ b/include/test.h
@@ -390,6 +390,21 @@ int tst_fs_fill_hardlinks(void (*cleanup) (void), const char *dir);
  */
 int tst_fs_fill_subdirs(void (*cleanup) (void), const char *dir);
 
+/*
+ * lib/system_specific_process_info.c
+ *
+ * Get a pid value not used by the OS
+ */
+pid_t tst_get_unused_pid(void (*cleanup_fn) (void));
+
+/*
+ * lib/system_specific_process_info.c
+ *
+ * Return a number of free pids by substracting the number
+ * of pid currently used ('ps -eT') from max_pids
+ */
+pid_t tst_get_free_pids(void (*cleanup_fn) (void));
+
 #ifdef TST_USE_COMPAT16_SYSCALL
 #define TCID_BIT_SUFFIX "_16"
 #elif  TST_USE_NEWER64_SYSCALL
diff --git a/lib/system_specific_process_info.c b/lib/system_specific_process_info.c
index bc47d49..105d806 100644
--- a/lib/system_specific_process_info.c
+++ b/lib/system_specific_process_info.c
@@ -1,6 +1,7 @@
 /*
  *
  *   Copyright (c) International Business Machines  Corp., 2009
+ *   Copyright (c) 2014 Oracle and/or its affiliates. All Rights Reserved.
  *
  *   This program is free software;  you can redistribute it and/or modify
  *   it under the terms of the GNU General Public License as published by
@@ -17,50 +18,28 @@
  *   Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
-/*
- *   DESCRIPTION
- *	get_max_pids(): Return the maximum number of pids for this system by
- *			reading /proc/sys/kernel/pid_max
- *
- *	get_free_pids(): Return number of free pids by subtracting the number
- *			 of pids currently used ('ps -eT') from max_pids
- */
-
 #include <fcntl.h>
 #include <limits.h>
 #include <sys/types.h>
 #include "test.h"
+#include "safe_file_ops.h"
 
-#define BUFSIZE 512
+#define PID_MAX_PATH "/proc/sys/kernel/pid_max"
 
-int get_max_pids(void)
+pid_t tst_get_unused_pid(void (*cleanup_fn) (void))
 {
-#ifdef __linux__
+	pid_t pid;
 
-	FILE *f;
-	char buf[BUFSIZE];
+	SAFE_FILE_SCANF(cleanup_fn, PID_MAX_PATH, "%d", &pid);
 
-	f = fopen("/proc/sys/kernel/pid_max", "r");
-	if (!f) {
-		tst_resm(TBROK, "Could not open /proc/sys/kernel/pid_max");
-		return -1;
-	}
-	if (!fgets(buf, BUFSIZE, f)) {
-		fclose(f);
-		tst_resm(TBROK, "Could not read /proc/sys/kernel/pid_max");
-		return -1;
-	}
-	fclose(f);
-	return atoi(buf);
-#else
-	return SHRT_MAX;
-#endif
+	return pid;
 }
 
-int get_free_pids(void)
+pid_t tst_get_free_pids(void (*cleanup_fn) (void))
 {
 	FILE *f;
-	int rc, used_pids, max_pids;
+	int rc;
+	pid_t used_pids, max_pids;
 
 	f = popen("ps -eT | wc -l", "r");
 	if (!f) {
@@ -76,10 +55,10 @@ int get_free_pids(void)
 		return -1;
 	}
 
-	max_pids = get_max_pids();
-
-	if (max_pids < 0)
-		return -1;
+	SAFE_FILE_SCANF(cleanup_fn, PID_MAX_PATH, "%d", &max_pids);
 
+	/* max_pids contains the maximum PID + 1,
+	 * used_pids contains used PIDs + 1,
+	 * so this additional '1' is eliminated by substraction*/
 	return max_pids - used_pids;
 }
diff --git a/testcases/kernel/syscalls/ipc/msgctl/msgctl11.c b/testcases/kernel/syscalls/ipc/msgctl/msgctl11.c
index 75d8bde..cffabf5 100644
--- a/testcases/kernel/syscalls/ipc/msgctl/msgctl11.c
+++ b/testcases/kernel/syscalls/ipc/msgctl/msgctl11.c
@@ -40,7 +40,6 @@
 #include "usctest.h"
 #include "ipcmsg.h"
 #include "../lib/libmsgctl.h"
-#include "system_specific_process_info.h"
 
 char *TCID = "msgctl11";
 int TST_TOTAL = 1;
@@ -475,7 +474,7 @@ void setup(void)
 
 	tst_resm(TINFO, "Found %d available message queues", MSGMNI);
 
-	free_pids = get_free_pids();
+	free_pids = tst_get_free_pids(cleanup);
 	if (free_pids < 0) {
 		tst_brkm(TBROK, cleanup, "Can't obtain free_pid count");
 	} else if (!free_pids) {
-- 
1.7.1


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