xentop segfault -- xenstat_domain_name returning a null pointer?

xentop segfault -- xenstat_domain_name returning a null pointer?

[Charles Duffy]

# xm list
Name                              ID Mem(MiB) VCPUs State  Time(s)
Domain-0                           0      512     1 r-----    41.8
demo-1                             1     1024     1 -b----    23.5
demo-2                             2     1024     1 -b----    23.1
demo-db                            3     2048     1 -b----    18.3
demo-vnc                           4      768     1 -b----     8.2
# gdb ./xentop
...
(gdb) run
Program received signal SIGSEGV, Segmentation fault.
[Switching to Thread 16384 (LWP 9196)]
0x00002aaaaae9253f in strcasecmp () from /lib/libc.so.6
(gdb) bt
#0  0x00002aaaaae9253f in strcasecmp () from /lib/libc.so.6
#1  0x0000000000401f51 in compare_name (domain1=0x5248d0, domain2=0x524920)
     at xentop.c:351
#2  0x0000000000401f1e in compare_domains (domain1=0x524a70, 
domain2=0x524a78)
     at xentop.c:343
#3  0x00002aaaaae541ed in bsearch () from /lib/libc.so.6
#4  0x00002aaaaae540e4 in bsearch () from /lib/libc.so.6
#5  0x00002aaaaae543c9 in qsort () from /lib/libc.so.6
#6  0x00000000004030aa in top () at xentop.c:788
#7  0x0000000000403346 in main (argc=1, argv=0x7fffffe4dd38) at xentop.c:873
(gdb) up
#1  0x0000000000401f51 in compare_name (domain1=0x5248d0, domain2=0x524920)
     at xentop.c:351
351             return strcasecmp(xenstat_domain_name(domain1), 
xenstat_domain_name(domain2));
(gdb) print xenstat_domain_name(domain1)
$5 = 0
(gdb) print xenstat_domain_name(domain2)
$6 = 5393056
(gdb) print (char*)xenstat_domain_name(domain2)
$7 = 0x524aa0 "demo-1"

Re: xentop segfault -- xenstat_domain_name returning a null pointer?

[David Hendricks]

Hello Mr. Duffy,
   Thank you for your detailed report on this problem. Unfortunately I
am bogged down with projects for school at the moment, but I will ping
my colleagues and see if we can get a solution for this by the end of
the week.

On Sun, 13 Nov 2005 20:55:40 -0600
Charles Duffy <cduffy@spamcop.net> wrote:

> # xm list
> Name                              ID Mem(MiB) VCPUs State  Time(s)
> Domain-0                           0      512     1 r-----    41.8
> demo-1                             1     1024     1 -b----    23.5
> demo-2                             2     1024     1 -b----    23.1
> demo-db                            3     2048     1 -b----    18.3
> demo-vnc                           4      768     1 -b----     8.2
> # gdb ./xentop
> ...
> (gdb) run
> Program received signal SIGSEGV, Segmentation fault.
> [Switching to Thread 16384 (LWP 9196)]
> 0x00002aaaaae9253f in strcasecmp () from /lib/libc.so.6
> (gdb) bt
> #0  0x00002aaaaae9253f in strcasecmp () from /lib/libc.so.6
> #1  0x0000000000401f51 in compare_name (domain1=0x5248d0,
> domain2=0x524920) at xentop.c:351
> #2  0x0000000000401f1e in compare_domains (domain1=0x524a70, 
> domain2=0x524a78)
>      at xentop.c:343
> #3  0x00002aaaaae541ed in bsearch () from /lib/libc.so.6
> #4  0x00002aaaaae540e4 in bsearch () from /lib/libc.so.6
> #5  0x00002aaaaae543c9 in qsort () from /lib/libc.so.6
> #6  0x00000000004030aa in top () at xentop.c:788
> #7  0x0000000000403346 in main (argc=1, argv=0x7fffffe4dd38) at
> xentop.c:873 (gdb) up
> #1  0x0000000000401f51 in compare_name (domain1=0x5248d0,
> domain2=0x524920) at xentop.c:351
> 351             return strcasecmp(xenstat_domain_name(domain1), 
> xenstat_domain_name(domain2));
> (gdb) print xenstat_domain_name(domain1)
> $5 = 0
> (gdb) print xenstat_domain_name(domain2)
> $6 = 5393056
> (gdb) print (char*)xenstat_domain_name(domain2)
> $7 = 0x524aa0 "demo-1"
> 
> 
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@lists.xensource.com
> http://lists.xensource.com/xen-devel


---------
David

Re: xentop segfault -- xenstat_domain_name returning a null pointer?

[Jerone Young]

This is odd if this is the case then you somehow you do not have a name
for your Domain-0 domain in xenstore. Not sure how exactly you get into
this situation. Are you still seeing this...grabbing todays hg build? I
am unable to reproduce your problem on any of my systems. 

If need be can add a check in the code to for NULL names...but the tools
do not allow you to have a domain without a name.

On Sun, 2005-11-13 at 20:55 -0600, Charles Duffy wrote:
> # xm list
> Name                              ID Mem(MiB) VCPUs State  Time(s)
> Domain-0                           0      512     1 r-----    41.8
> demo-1                             1     1024     1 -b----    23.5
> demo-2                             2     1024     1 -b----    23.1
> demo-db                            3     2048     1 -b----    18.3
> demo-vnc                           4      768     1 -b----     8.2
> # gdb ./xentop
> ...
> (gdb) run
> Program received signal SIGSEGV, Segmentation fault.
> [Switching to Thread 16384 (LWP 9196)]
> 0x00002aaaaae9253f in strcasecmp () from /lib/libc.so.6
> (gdb) bt
> #0  0x00002aaaaae9253f in strcasecmp () from /lib/libc.so.6
> #1  0x0000000000401f51 in compare_name (domain1=0x5248d0, domain2=0x524920)
>      at xentop.c:351
> #2  0x0000000000401f1e in compare_domains (domain1=0x524a70, 
> domain2=0x524a78)
>      at xentop.c:343
> #3  0x00002aaaaae541ed in bsearch () from /lib/libc.so.6
> #4  0x00002aaaaae540e4 in bsearch () from /lib/libc.so.6
> #5  0x00002aaaaae543c9 in qsort () from /lib/libc.so.6
> #6  0x00000000004030aa in top () at xentop.c:788
> #7  0x0000000000403346 in main (argc=1, argv=0x7fffffe4dd38) at xentop.c:873
> (gdb) up
> #1  0x0000000000401f51 in compare_name (domain1=0x5248d0, domain2=0x524920)
>      at xentop.c:351
> 351             return strcasecmp(xenstat_domain_name(domain1), 
> xenstat_domain_name(domain2));
> (gdb) print xenstat_domain_name(domain1)
> $5 = 0
> (gdb) print xenstat_domain_name(domain2)
> $6 = 5393056
> (gdb) print (char*)xenstat_domain_name(domain2)
> $7 = 0x524aa0 "demo-1"
> 
> 
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