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Message-ID: <55CB4BD4.5050200@ndmsystems.com>
Date: Wed, 12 Aug 2015 16:36:20 +0300
From: Eugene <e.yudin@...systems.com>
To: musl@...ts.openwall.com
Subject: Thread hangs up when calling exit()
Hello,
I have problem with threads.
Main thread waits for input through function fgets().
Other thread calls function exit() and hangs up.
Main thread continues working.
Musl version: 1.1.10.
Example:
#include <pthread.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
void *func(void *arg)
{
printf("New thread...\n");
sleep(5);
exit(EXIT_SUCCESS);
return (void *) 0;
}
int main(int argc, char *argv[])
{
char buf[100];
int res = EXIT_FAILURE, ret;
pthread_t tid;
ret = pthread_create(&tid, NULL, func, NULL);
if (ret) {
fprintf(stderr, "pthread_create: %s\n", strerror(ret));
goto out;
}
while (fgets(buf, sizeof buf, stdin) != NULL)
printf("buf = %s\n", buf);
res = EXIT_SUCCESS;
out:
return res;
}
Expected result: program exits.
Actual results: main thread continues working.
Correct behavior may be obtained with following patch:
diff --git a/src/stdio/__stdio_exit.c b/src/stdio/__stdio_exit.c
index 191b445..71a9677 100644
--- a/src/stdio/__stdio_exit.c
+++ b/src/stdio/__stdio_exit.c
@@ -17,7 +17,7 @@ void __stdio_exit(void)
{
FILE *f;
for (f=*__ofl_lock(); f; f=f->next) close_file(f);
- close_file(__stdin_used);
+ //close_file(__stdin_used);
close_file(__stdout_used);
}
Maybe "__stdin_used" must be replaced with "__stderr_used"?
It's looking strange for me to write and seek stdin in function
close_file().
Function fgets() obtains lock via macro FLOCK.
close_file() in "__stdio_exit.c" tries to obtain the same lock.
It leads to thread hangup.
Eugene
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