Re: [PATCH] powerpc/modules: Use WARN_ON() in stub_for_addr()

[Kamalesh Babulal <kamalesh@linux.vnet.ibm.com>]

On Wednesday 11 October 2017 09:42 AM, Michael Ellerman wrote:
> Kamalesh Babulal <kamalesh@linux.vnet.ibm.com> writes:
> 
>> Use WARN_ON(), while running out of stubs in stub_for_addr()
>> and abort loading of the module instead of BUG_ON().
> 
> Thanks. This looks good in principle. Have you actually tested it to
> make sure we do in fact gracefully fail the module load?
> 

Thanks for the review. I tested with little hackish version of this patch:

+       if (!strncmp(me->name, "live", 4))
+               j = 100;
+       for (i = 0; stub_func_addr(stubs[i].funcdata); i+=j) {
+               if (WARN_ON(i >= num_stubs))
+                       return 0;

and it fails gracefully.

# modprobe livepatch-sample
modprobe: ERROR: could not insert 'livepatch_sample': Unknown symbol in module, or unknown parameter (see dmesg)

# echo $?
1

# dmesg 
------------[ cut here ]------------
WARNING: CPU: 2 PID: 2836 at arch/powerpc/kernel/module_64.c:526 apply_relocate_add+0x71c/0xb00

-- 
cheers,
Kamalesh.