[LTP] [PATCH] lib/tst_res.c: synchronize access to tst_res functions

[LTP] [PATCH] lib/tst_res.c: synchronize access to tst_res functions

[Alexey Kodanev]

The patch adds synchronization mechanism which is required (tst_res.c
uses global variables e.g. T_exitval, tst_count, T_out, ...) when tst_res
functions are used in multi-threaded tests.
Note: it will only work if test is linked with pthread library, also some
functions include each other that is why recursive mutex is used (can be
locked several times by the same thread).

Signed-off-by: Alexey Kodanev <alexey.kodanev@oracle.com>
---
 lib/tst_res.c |   28 +++++++++++++++++++++++++---
 1 files changed, 25 insertions(+), 3 deletions(-)

diff --git a/lib/tst_res.c b/lib/tst_res.c
index 2a3eff6..8faa5a9 100644
--- a/lib/tst_res.c
+++ b/lib/tst_res.c
@@ -93,6 +93,7 @@
 
 #define _GNU_SOURCE		/* for asprintf */
 
+#include <pthread.h>
 #include <assert.h>
 #include <errno.h>
 #include <stdio.h>
@@ -138,6 +139,8 @@ pid_t spawned_program_pid;
 	assert(strlen(buf) > 0);		\
 } while (0)
 
+static pthread_mutex_t tmutex = PTHREAD_RECURSIVE_MUTEX_INITIALIZER_NP;
+
 /*
  * Define local function prototypes.
  */
@@ -226,6 +229,8 @@ const char *strttype(int ttype)
  */
 void tst_res(int ttype, const char *fname, const char *arg_fmt, ...)
 {
+	pthread_mutex_lock(&tmutex);
+
 	char tmesg[USERMESG];
 	int ttype_result = TTYPE_RESULT(ttype);
 
@@ -286,6 +291,7 @@ void tst_res(int ttype, const char *fname, const char *arg_fmt, ...)
 		tst_count++;
 	}
 
+	pthread_mutex_unlock(&tmutex);
 }
 
 /*
@@ -351,6 +357,8 @@ static void tst_condense(int tnum, int ttype, const char *tmesg)
  */
 void tst_flush(void)
 {
+	pthread_mutex_lock(&tmutex);
+
 #if DEBUG
 	printf("IN tst_flush\n");
 	fflush(stdout);
@@ -365,6 +373,8 @@ void tst_flush(void)
 	}
 
 	fflush(T_out);
+
+	pthread_mutex_unlock(&tmutex);
 }
 
 /*
@@ -537,6 +547,8 @@ static void check_env(void)
  */
 void tst_exit(void)
 {
+	pthread_mutex_lock(&tmutex);
+
 #if DEBUG
 	printf("IN tst_exit\n");
 	fflush(stdout);
@@ -568,10 +580,13 @@ pid_t tst_vfork(void)
  */
 int tst_environ(void)
 {
+	pthread_mutex_lock(&tmutex);
+	int ret = 0;
 	if ((T_out = fdopen(dup(fileno(stdout)), "w")) == NULL)
-		return -1;
-	else
-		return 0;
+		ret = -1;
+
+	pthread_mutex_unlock(&tmutex);
+	return ret;
 }
 
 /*
@@ -586,6 +601,8 @@ static int tst_brk_entered = 0;
  */
 void tst_brk(int ttype, const char *fname, void (*func) (void), const char *arg_fmt, ...)
 {
+	pthread_mutex_lock(&tmutex);
+
 	char tmesg[USERMESG];
 	int ttype_result = TTYPE_RESULT(ttype);
 
@@ -633,6 +650,7 @@ void tst_brk(int ttype, const char *fname, void (*func) (void), const char *arg_
 	if (tst_brk_entered == 0)
 		tst_exit();
 
+	pthread_mutex_unlock(&tmutex);
 }
 
 /*
@@ -659,6 +677,8 @@ void tst_resm(int ttype, const char *arg_fmt, ...)
  */
 void tst_resm_hexd(int ttype, const void *buf, size_t size, const char *arg_fmt, ...)
 {
+	pthread_mutex_lock(&tmutex);
+
 	char tmesg[USERMESG];
 
 #if DEBUG
@@ -692,6 +712,8 @@ void tst_resm_hexd(int ttype, const void *buf, size_t size, const char *arg_fmt,
 			pmesg = tmesg;
 		}
 	}
+
+	pthread_mutex_unlock(&tmutex);
 }
 
 /*
-- 
1.7.1


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Re: [LTP] [PATCH] lib/tst_res.c: synchronize access to tst_res functions

[chrubis]

Hi!
> The patch adds synchronization mechanism which is required (tst_res.c
> uses global variables e.g. T_exitval, tst_count, T_out, ...) when tst_res
> functions are used in multi-threaded tests.
> Note: it will only work if test is linked with pthread library, also some
> functions include each other that is why recursive mutex is used (can be
> locked several times by the same thread).

This looks good to me.

Mike can you have a look, just to be extra sure.

-- 
Cyril Hrubis
chrubis@suse.cz

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Re: [LTP] [PATCH] lib/tst_res.c: synchronize access to tst_res functions

[chrubis]

Hi!
> > The patch adds synchronization mechanism which is required (tst_res.c
> > uses global variables e.g. T_exitval, tst_count, T_out, ...) when tst_res
> > functions are used in multi-threaded tests.
> > Note: it will only work if test is linked with pthread library, also some
> > functions include each other that is why recursive mutex is used (can be
> > locked several times by the same thread).
> 
> This looks good to me.
> 
> Mike can you have a look, just to be extra sure.
> 

Ping.

-- 
Cyril Hrubis
chrubis@suse.cz

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Re: [LTP] [PATCH] lib/tst_res.c: synchronize access to tst_res functions

[chrubis]

Hi!
> The patch adds synchronization mechanism which is required (tst_res.c
> uses global variables e.g. T_exitval, tst_count, T_out, ...) when tst_res
> functions are used in multi-threaded tests.
> Note: it will only work if test is linked with pthread library, also some
> functions include each other that is why recursive mutex is used (can be
> locked several times by the same thread).

I've reworded the commit message a bit to make it (hopefully) more
clear and pushed the change. Thanks.

PS: Can you add a paragraph about thread safety and about the once
    callback macro to test-writing-guidelines or should I write it?

-- 
Cyril Hrubis
chrubis@suse.cz

------------------------------------------------------------------------------
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"Graph Databases" is the definitive new guide to graph databases and their
applications. Written by three acclaimed leaders in the field,
this first edition is now available. Download your free book today!
http://p.sf.net/sfu/13534_NeoTech
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