Date: Fri, 6 Feb 2004 09:34:14 -0500 (EST) From: Daniel Eischen <eischen@vigrid.com> To: Alexey Zelkin <phantom@FreeBSD.org.ua> Cc: freebsd-threads@freebsd.org Subject: Re: runtime checking of thread libraries mixup Message-ID: <Pine.GSO.4.10.10402060925470.7873-100000@pcnet5.pcnet.com> In-Reply-To: <20040206130800.GA29843@phantom.cris.net>
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On Fri, 6 Feb 2004, Alexey Zelkin wrote:
> hi,
>
> Some time ago (after switch of jdk14 port to libkse as default thread
> library) a lot of people reported problems about strange things happened
> after jdk14 port upgrade. Most of these problems were related to
> libc_r/libkse libraries mixup (i.e. one library was linked against
> libc_r and another against libkse). Short term fix to them was suggestion
> to map (via libmap) libkse -> libc_r. Long term way is to recompile
> everything. This problematic time caused me to think -- why no runtime
> checks against this issue are present.
>
> Today I got an idea and implemented it in below patch. Unfortunately
> this patch is not even compile tested since my -CURRENT machine is down
> now, so I unable to test in action as well. But it would be nice to hear
> that do you think about concept and realization of this idea.
>
> Attached patch is against libc_r, but code for libpthread and libthr should
> be absolutely same, with small 'THIS' and 'another' values tweaking.
I was working on something similar but different ;-) I added
"extern int __thrlib_type" to libc/include/libc_private.h and
set it to 0 in libc/stdlib/exit.c (just like __isthreaded).
Then I had libc_r and libpthread check it and set it to different
unique values in their versions of uthread_init.c. This didn't
quite work correctly because spinlocks were still being confused
between libraries (still got same spinlock errors). I think
it could be fixed by adding checks to the spinlock functions
but I didn't really want to added additional code to them.
In the end, I thought that the spinlock error messages
were just as good an indication that you had linked
to multiple libraries as "you have linked to multiple
thread libraries" ;-)
>
> Index: uthread_init.c
> ===================================================================
> RCS file: /home/ncvs/src/lib/libc_r/uthread/uthread_init.c,v
> retrieving revision 1.46
> diff -u -r1.46 uthread_init.c
> --- uthread_init.c 3 Dec 2003 06:54:40 -0000 1.46
> +++ uthread_init.c 6 Feb 2004 12:58:55 -0000
> @@ -64,6 +64,10 @@
> #include <stdlib.h>
> #include <string.h>
> #include <unistd.h>
> +#ifdef CHECK_LIBRARIES_MIX
> +#include <link.h>
> +#include <dlfcn.h>
> +#endif
> #include "un-namespace.h"
>
> #include "libc_private.h"
> @@ -72,6 +76,9 @@
> int __pthread_cond_wait(pthread_cond_t *, pthread_mutex_t *);
> int __pthread_mutex_lock(pthread_mutex_t *);
> int __pthread_mutex_trylock(pthread_mutex_t *);
> +#ifdef CHECK_LIBRARIES_MIX
> +static void check_libraries_mix(void);
> +#endif
>
> /*
> * All weak references used within libc should be in this table.
> @@ -221,6 +228,9 @@
> /* Only initialise the threaded application once. */
> return;
>
> +#ifdef CHECK_LIBRARIES_MIX
> + check_libraries_mix();
> +#endif
> _pthread_page_size = getpagesize();;
> _pthread_guard_default = _pthread_page_size;
> sched_stack_size = 4 * _pthread_page_size;
> @@ -563,5 +573,37 @@
> {
> _thread_init();
> return (main(argc, argv, env));
> +}
> +#endif
> +
> +/*
> + * Check if threading libraries are mixed
> + */
> +#ifdef CHECK_LIBRARIES_MIX
> +static void
> +check_libraries_mix(void)
> +{
> + Link_map *map;
> + char *another [] = { "libpthread", "libkse", "libthr" };
> + char *s[80];
> + int i;
> +
> +#define ANOTHERSZ (sizeof(another)/sizeof(another[0]))
> +#define THIS "libc_r"
> +#define MSG "DANGER: Thread libraries mixup: both " THIS " and %s are used\n"
> +
> + dlinfo(RTLD_SELF, RTLD_DI_LINKMAP, &map);
> + while (map != NULL) {
> + if (strstr(map->l_name, "lib") != NULL) {
> + for (i = 0; i++; i < ANOTHERSZ) {
> + if (strstr(map->l_name, another[i])) {
> + snprintf(s, sizeof(s), MSG, another[i]);
> + __sys_write(2, s, strlen(s));
> + return;
> + }
> + }
> + }
> + map = map->l_next;
> + }
> }
> #endif
>
> --
> /* Alexey Zelkin && Independent Contractor */
> /* phantom(at)FreeBSD.org && http://www.FreeBSD.org/java */
> /* phantom(at)cris.net && http://www.FreeBSD.org.ua/ */
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--
"Some folks are into open source, but me, I'm into open bar."
-- Spencer F. Katt
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