On 04.12.20 09:30, Jan Beulich wrote:
> On 01.12.2020 09:21, Juergen Gross wrote:
>> @@ -100,11 +112,58 @@ static void hypfs_unlock(void)
>>       }
>>   }
>>   
>> +const struct hypfs_entry *hypfs_node_enter(const struct hypfs_entry *entry)
>> +{
>> +    return entry;
>> +}
>> +
>> +void hypfs_node_exit(const struct hypfs_entry *entry)
>> +{
>> +}
>> +
>> +static int node_enter(const struct hypfs_entry *entry)
>> +{
>> +    const struct hypfs_entry **last = &this_cpu(hypfs_last_node_entered);
>> +
>> +    entry = entry->funcs->enter(entry);
>> +    if ( IS_ERR(entry) )
>> +        return PTR_ERR(entry);
>> +
>> +    ASSERT(!*last || *last == entry->parent);
>> +
>> +    *last = entry;
> 
> In such a callback case I wonder whether you wouldn't want to also
> guard against NULL coming back, perhaps simply by mistake, but of
> course once handling it here such could even become permissible
> behavior.

I think you are right. I should add an ASSERT(entry);


Juergen