Re: Why __libc_internal_tsd_get/__libc_internal_tsd_set

[Zack Weinberg <zack@rabi.columbia.edu>]

On Fri, 19 Mar 1999 14:13:19 -0500, Roland McGrath wrote:
>> It only works with static libraries.  It doesn't work with shared
>> libraries. To work with shared libraries, weak symbols should be used
>> instead.
>
>You have not told us about any specific problem or given us any reason to
>believe there is in fact a problem.  If you want anyone to do anything
>about the bugs you claim to find, then you have to show us the bugs.

I suspect based on context that this has to do with the appended program,
which is reported to segfault inside malloc on 2.0. I would test it on 2.1
but my machine is dead right now.

I have no idea why HJ thinks the fix is to muck around with the symbol
table.  It looks to me like a locking bug.

zw

-----------------------------------------
#include <pthread.h>
#include <stdio.h>

pthread_key_t key;

void* main_thr(void* v)
{
   void *a, *b, *c, *d, *e, *f;
   pthread_setspecific(key, "asd");
   a=malloc(4);
   b=malloc(36);
   c=malloc(20);
   d=malloc(20);
   e=malloc(24);
   f=malloc(24);
   free(f);
   f=malloc(4440);
   free(malloc(4440));
   free(a);free(b);free(c);
   pthread_setspecific(key, NULL);
}

int main()
{
   pthread_t t_id;
   pthread_key_create(&key, NULL);
   pthread_create(&t_id, NULL, main_thr,(void*)0);
   pthread_join(t_id, NULL);
/*   sleep(1);*/
   pthread_key_delete(key);
   free(malloc(1));
   return 0;
}

/* The program ends with SIGSEGV in the last malloc.
   But when sleep(1) is uncommented it runs successfully. 
   Presumably there is some sort of race.  */