Joerg Sonnenberger <jo...@britannica.bec.de> wrote:
> I maintain that trying to move contexts between threads is an inherently
> bad idea and that it is a very inefficient interface for implementing
> coroutines. I object to this change for the sake of misdesigned
> software.
Did you look at that test case? This is a nasty bug, and I think we need
a way for user to opt out of that behavior.
# ./tss
thread 1 self = 0xbfa00000
before swapcontext self = 0xbb600000
after swapcontext self = 0xbfa00000
thread 2 self = 0xbfa00000
thread 1 self = 0xbfa00000
thread 2 self = 0xbfa00000
thread 1 self = 0xbfa00000
thread 2 self = 0xbfa00000
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <pthread.h>
#include <err.h>
#include <sysexits.h>
#include <signal.h>
#ifdef __linux__
#include <bits/sigstack.h>
#endif
#include <ucontext.h>
char stack[66536];
ucontext_t ctx;
ucontext_t octx;
void wrap(int);
void *thread1(void *);
void
wrap(cookie)
int cookie;
{
printf("after swapcontext self = %p\n", (void *)pthread_self());
do {
printf("thread 2 self = %p\n", (void *)pthread_self());
sleep (1);
} while (1 /* CONSTCOND */);
return;
}
void *
thread1(arg)
void *arg;
{
usleep(50);
ctx.uc_stack.ss_sp = stack;
ctx.uc_stack.ss_size = sizeof(stack);
makecontext(&ctx, (void *)*wrap, 2, (int)0xdeadbeef);
printf("before swapcontext self = %p\n", (void
*)pthread_self());
if (swapcontext(&octx, &ctx) != 0)
err(EX_OSERR, "swapcontext failed");
errx(EX_SOFTWARE, "swapcontext returned");
/* NOTREACHED */
return NULL;
}
int
main(argc, argv)
int argc;
char **argv;
{
int error;
pthread_t th;
if ((error = pthread_create(&th, NULL, *thread1, NULL)) != 0)
err(EX_OSERR, "pthread_create returns error = %d",
error);
if (getcontext(&ctx) != 0)
err(EX_OSERR, "getcontext failed");
do {
printf("thread 1 self = %p\n", (void *)pthread_self());
sleep (1);
} while (1 /* CONSTCOND */);
/* NOTREACHED */
return EX_OK;
}
--
Emmanuel Dreyfus
http://hcpnet.free.fr/pubz
m...@netbsd.org
