svn commit: r214125 - head/sys/kern

[Xin LI]

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On 10/21/10 04:46, John Baldwin wrote:
> On Thursday, October 21, 2010 4:57:25 am Xin LI wrote:
>> Author: delphij
>> Date: Thu Oct 21 08:57:25 2010
>> New Revision: 214125
>> URL: http://svn.freebsd.org/changeset/base/214125
>>
>> Log:
>>   In syscall_module_handler(): all switch branches return, remove
>>   unreached code as pointed out in a Chinese forum [1].
>>   
>>   [1] http://www.freebsdchina.org/forum/viewtopic.php?t=50619
>>   
>>   Pointed out by:		btw616 <btw s qq com>
>>   MFC after:		1 month
> 
> I think this exposes a bug though in that the default case doesn't pass 
> through to chainevh.  The default case should look more like the removed code 
> (except returning EOPNOTSUPP instead of 0 if there is no chainevh).

Hmm...  It sounds reasonable in theory (so that modules can handle
events other than MOD_LOAD/UNLOAD) at least, while I don't think it's
really being used anywhere.

Will the attached patch look reasonable?  (If data->chainevh is NULL
then operation is not supported, if not then delegate to the module).

Cheers,
- -- 
Xin LI <delphij at delphij.net>	http://www.delphij.net/
FreeBSD - The Power to Serve!	       Live free or die
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-------------- next part --------------
Index: sys/kern/kern_syscalls.c
===================================================================
--- sys/kern/kern_syscalls.c	(revision 214146)
+++ sys/kern/kern_syscalls.c	(working copy)
@@ -181,7 +181,9 @@
 		error = syscall_deregister(data->offset, &data->old_sysent);
 		return (error);
 	default:
-		return EOPNOTSUPP;
+		if (data->chainevh)
+			return (data->chainevh(mod, what, data->chainarg));
+		return (EOPNOTSUPP);
 	}
 
 	/* NOTREACHED */