Re: [uml-devel] [patch] Re: Reboot failing with file locked, CLONE_FILES and host kernel BUG()

[Marcin Pawlik <wapkil@op.pl>]

On Wed, Apr 14 at 16:44, Henrik Nordstrom wrote:
> On Wed, 14 Apr 2004, Marcin Pawlik wrote:
> 
>> Do you know where and which thread closes the files? I tried to add
>> file closing to kill_io_thread() (patch attached) and it helps but I
>> think it should also be performed without my code.
> 
> No, I do not remember, but the thread which originally opened and
> locked the file is apparently not around after the UML has booted.

Yes, but this is not necessarily a problem. Any thread sharing file
description table can close (and therefore unlock) the file.

[...]
>>>  int os_lock_file(int fd, int excl)
>>>  {
>>> +#if USE_FCNTL_LOCK
>>>  	int type = excl ? F_WRLCK : F_RDLCK;
>>>  	struct flock lock = ((struct flock) { .l_type	= type,
>>>  					      .l_whence	= SEEK_SET,
>>> @@ -710,6 +711,21 @@
>>>  	err = save;
>>>   out:
>>>  	return(err);
>>> +#else
>>> +	int type = excl ? LOCK_EX : LOCK_SH;
>> 
>> I don't understand this. IMO excl should be F_RDLCK or F_WRLCK.
>> F_RDLCK is 0, F_WRLCK is 1 and LOCK_EX is 2 so you will always use
>> LOCK_SH.
> 
> ???
> 
> excl is a boolean, true if the lock should be exclusive (write

Ups. Yes, you are absolutely right. I thought... Well I don't know.
I'm sorry. Probably I should take some sleep :/

[...]
> Seems to works here.. there os no other uses of F_SETLK in my uml
> tree.  Using this successfully on RedHat-8 (2.4.20 somthing host
> kernel, no SKAS)  and Fedora Core 2 test 1 + SKAS (2.6.something +
> SKAS host kernel)..

I tried it on Debian testing/unstable with different host kernels
(2.4.25, 2.4.25 with skas, 2.6.5, 2.4.18-1-k7 from Debian) and the same
binary on RHEL 3.0 with some 2.4.21. Doesn't work for me. After "cad" or
"halt" in uml_mconsole I have sleeping and traced proceses left. 

I placed my testing UML binary and the filesystem (infinite loop in
/sbin/init) on http://www.pwr.wroc.pl/~marcinp/uml/uml.tar.gz (~1.2 MB).
Maybe it depends on UML configuration or compiler used. Could you send
me your --showconfig?

Regards,

-- 
Marcin Pawlik


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