----- On Oct 17, 2018, at 11:00 AM, Mathieu Desnoyers mathieu.desnoyers@xxxxxxxxxxxx wrote:
> ----- On Oct 16, 2018, at 8:27 PM, Sergey Senozhatsky
> sergey.senozhatsky.work@xxxxxxxxx wrote:
>
>> On (10/16/18 14:30), Steven Rostedt wrote:
>>> > +void vm_unmap_user_ram(const void *mem, unsigned int count)
>>> > +{
>>> > + unsigned long size = (unsigned long)count << PAGE_SHIFT;
>>> > + unsigned long addr = (unsigned long)mem;
>>> > + struct vmap_area *va;
>>> > +
>>> > + might_sleep();
>>> > + BUG_ON(!addr);
>>> > + BUG_ON(addr < VMALLOC_START);
>>> > + BUG_ON(addr > VMALLOC_END);
>>> > + BUG_ON(!PAGE_ALIGNED(addr));
>>> > +
>>> > + debug_check_no_locks_freed(mem, size);
>>> > + va = find_vmap_area(addr);
>>> > + BUG_ON(!va);
>>> > + free_unmap_vmap_area(va);
>>> > +}
>>> > +EXPORT_SYMBOL(vm_unmap_user_ram);
>>> > +
>>>
>>> Noticing this from Sergey's question in another patch, why are you
>>> using BUG_ON()? That's rather extreme and something we are trying to
>>> avoid adding more of (I still need to remove the BUG_ON()s I've added
>>> over ten years ago). I don't see why all these BUG_ON's can't be turned
>>> into:
>>
>> +1
>>
>>> if (WARN_ON(x))
>>> return;
>>
>> Given that this somewhat MM-related, I'd may be say VM_WARN_ON().
I notice that VM_WARN_ON() casts the result of WARN_ON() to (void), so it
cannot be used in a if () statement.
VM_WARN_ON() will only warn if CONFIG_DEBUG_VM is set.
Is it really what we want ?
Thanks,
Mathieu
>
> Good point, will do!
>
> So I'll do one cleanup patch for vm_unmap_ram(), and I'll modify the new
> vm_unmap_user_ram().
>
> Thanks,
>
> Mathieu
>
>>
>> -ss
>
> --
> Mathieu Desnoyers
> EfficiOS Inc.
> http://www.efficios.com
--
Mathieu Desnoyers
EfficiOS Inc.
http://www.efficios.com
