Re: [Xen-devel] [PATCH V5 10/12] xen/vm_event: Relocate memop checks

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 17.02.15 at 19:47, <tamas.lengyel@xxxxxxxxxxxx> wrote:
> On Tue, Feb 17, 2015 at 3:25 PM, Jan Beulich <JBeulich@xxxxxxxx> wrote:
>>>>> On 13.02.15 at 17:33, <tamas.lengyel@xxxxxxxxxxxx> wrote:
>>> -int mem_paging_memop(struct domain *d, xen_mem_paging_op_t *mpo)
>>> +int mem_paging_memop(unsigned long cmd,
>>> +                     XEN_GUEST_HANDLE_PARAM(xen_mem_paging_op_t) arg)
>>>  {
>>> -    int rc = -ENODEV;
>>> +    int rc;
>>> +    xen_mem_paging_op_t mpo;
>>> +    struct domain *d;
>>> +
>>> +    rc = -EFAULT;
>>> +    if ( copy_from_guest(&mpo, arg, 1) )
>>> +        return rc;
>>
>> Please don't make things more complicated than they need to be:
>> You only use the -EFAULT once here, so no reason to assign it to
>> rc up front.
> 
> This return will be a "goto out;" where the rcu is getting unlocked as well.

How that? You didn't take the RCU lock yet (which is even visible
from the rest of the hunk above).

Jan


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