From mboxrd@z Thu Jan  1 00:00:00 1970
From: Ross Lagerwall <ross.lagerwall@citrix.com>
Subject: Re: [PATCH v1 10/11] xsplice: Add support for exception
 tables
Date: Fri, 27 Nov 2015 17:05:32 +0000
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To: Martin Pohlack <mpohlack@amazon.com>, xen-devel@lists.xen.org
Cc: Andrew Cooper <andrew.cooper3@citrix.com>, Jan Beulich <jbeulich@suse.com>
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On 11/27/2015 04:28 PM, Martin Pohlack wrote:
> On 03.11.2015 19:16, Ross Lagerwall wrote:
>> +#ifdef CONFIG_X86
>> +unsigned long search_module_extables(unsigned long addr)
>> +{
>> +    struct payload *data;
>> +    unsigned long ret;
>> +
>> +    /* No locking since this list is only ever changed during apply or revert
>> +     * context. */
>
> How do you make sure that no exception is triggered in the patching
> process itself (also for future code changes)?
>
> Could we use a lockless update on the list of module ex-tables?
>

That seems like overkill. The patching process either simply does 
list_add_tail or list_del to update the list, so unless you expect those 
to generate exceptions, I don't think you gain anything by doing 
lockless updates.

-- 
Ross Lagerwall