On 2005-06-14, at 14:08, Vasil Dimov wrote:
makecontext(&ctx_cleanup, ctx_cleanup_func, 0);Changing the currently executing context (with makecontext) does not seem very robust to me, but, however, I am not an ucontext expert (in fact I have not heard about it before beginning to experience problems with stunnel-4.10).
makecontext(3) only prepares the structure. setcontext(2) modifies the context.
Hmm, what is this version of stunnel?
4.10 + some diagnostic code.
4.10 does not print "Switching from context M to context N", "Context switched", etc.
Is the number after the pid showing the thread id? How is it possible that context2 prints "Switching from context 1 to context 2", shouldnt this be printed by context 1?
Context 2 is already in the ready queue. The code is: /* switch the context */ if(fds) { /* swap the context */ s_log(LOG_DEBUG, "Switching from context %ld to context %ld", ctx->id, ready_head->id); swapcontext(&ctx->ctx, &ready_head->ctx); s_log(LOG_DEBUG, "Context switched"); return ready_head->ready; } else { /* drop the context */ setcontext(&ready_head->ctx); ioerror("setcontext"); /* should not ever happen */ return 0; }
Do you confirm that stunnel begins to crash after applying bsd.patch on your User-Mode Linux?
No. It has nothing to do with bsd.patch
Does the Context 2 function start execution at all, or the program crashes before that?
The crash is on swapcontext().
I noticed that backtraces of ucontexting programs are not very useful, but can you retrieve a backtrace from the core file? What does it show?
It seems smashed.
Program received signal SIGSEGV, Segmentation fault. [Switching to Thread 16384 (LWP 704)] 0x40020bae in _pthread_cleanup_push_defer () from /lib/libpthread.so.0 (gdb) bt #0 0x40020bae in _pthread_cleanup_push_defer () from /lib/libpthread.so.0 #1 0x401f702c in vfprintf () from /lib/libc.so.6 #2 0x401f2ec0 in vfprintf () from /lib/libc.so.6 #3 0x401fb94f in fprintf () from /lib/libc.so.6 #4 0x0804df97 in s_log (level=134571040, format=0x402d5440 "\207(??\207T-@\207T-@\207T-@\207T-@\207T-@\207T-@\207T-@\210T-@") at log.c:152 #5 0x0804b514 in client (arg=0x807d960) at client.c:106 #6 0x401f0674 in makecontext () from /lib/libc.so.6 #7 0x0807d960 in ?? () #8 0x0805eca0 in next_id () #9 0x00000002 in ?? () #10 0x00000000 in ?? () #11 0x0805eca0 in next_id () #12 0x08085ed0 in ?? () #13 0x00000000 in ?? () #14 0x00010000 in ?? () #15 0x00000000 in ?? () #16 0x00000000 in ?? () #17 0x00000000 in ?? () #18 0x00000000 in ?? () #19 0xbffff99c in ?? () #20 0x00000009 in ?? ()
Best regards, Mike