Re: [Xen-devel] [PATCH] xenstore: set READ_THREAD_STACKSIZE to a sane value

[Roger Pau Monnà <roger.pau@xxxxxxxxxx>]

On 11/03/14 14:24, Ian Campbell wrote:
> On Mon, 2014-03-10 at 17:12 +0000, Ian Jackson wrote:
>> Roger Pau Monne writes ("[PATCH] xenstore: set READ_THREAD_STACKSIZE to a 
>> sane value"):
>>> On FreeBSD PTHREAD_STACK_MIN is 2048 by default, which is obviously
>>> too low.
> 
> How does this manifest itself? (I suppose this may be answered as part
> of answering Ian J)

Yes, I'm still looking into it, this gdb output:

Starting program: /usr/local/bin/xenstore-watch /foo
[New LWP 100169]
[New Thread 801406800 (LWP 100182/xenstore-watch)]

Program received signal SIGSEGV, Segmentation fault.
[Switching to Thread 801406800 (LWP 100182/xenstore-watch)]
0x0000000800ac1258 in sbrk () from /lib/libc.so.7
(gdb) bt
#0  0x0000000800ac1258 in sbrk () from /lib/libc.so.7
#1  0x0000000800ac110e in sbrk () from /lib/libc.so.7
#2  0x0000000800ac9ee8 in sbrk () from /lib/libc.so.7
#3  0x0000000800ac456b in sbrk () from /lib/libc.so.7
#4  0x0000000800ac447d in sbrk () from /lib/libc.so.7
#5  0x0000000800aaf6ce in syscall () from /lib/libc.so.7
#6  0x0000000800acb37b in malloc () from /lib/libc.so.7
#7  0x00000008008202b9 in read_message (h=0x801417080, nonblocking=0) at 
xs.c:313
#8  0x0000000800820a06 in read_thread (arg=0x801417080) at xs.c:313
#9  0x0000000800dc64a4 in pthread_create () from /lib/libthr.so.3
#10 0x0000000000000000 in ?? ()

I've also tried to debug it using valgrind, and here's what I got:

[root@loki ~/xen/xen]# valgrind xenstore-watch /foo
==1901== Memcheck, a memory error detector
==1901== Copyright (C) 2002-2012, and GNU GPL'd, by Julian Seward et al.
==1901== Using Valgrind-3.8.1 and LibVEX; rerun with -h for copyright info
==1901== Command: xenstore-watch /foo
==1901==
==1901== Syscall param socketcall.connect(serv_addr..sa_len) points to 
uninitialised byte(s)
==1901==    at 0x152A14A: connect (in /lib/libc.so.7)
==1901==    by 0x1210B46: get_handle (xs.c:205)
==1901==    by 0x1210CEC: xs_open (xs.c:297)
==1901==    by 0x4027B1: main (xenstore_client.c:635)
==1901==  Address 0x7ff000a70 is on thread 1's stack
==1901==
/foo

Strangely enough, when running under valgrind it doesn't segfault, and 
I'm still trying to figure out why valgrind complains.

Roger.

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