Re: [PATCH] drm/ttm: do not check if list is empty in ttm_bo_force_list_clean, v2

[Thomas Hellstrom <thellstrom@vmware.com>]

On 11/30/2012 11:16 AM, Maarten Lankhorst wrote:
> Op 30-11-12 10:04, Thomas Hellstrom schreef:
>> On 11/30/2012 09:05 AM, Maarten Lankhorst wrote:
>>> Just use the return error from ttm_mem_evict_first instead.
>>>
>>> Changes since v1:
>>> - Add warning if list is not empty, nothing else we can do here.
>> Marten, when this function is called, all cross-device reservers have been shut out with the TTM lock or whatever similar
>> mechanism is in place. It's a critical function that must succeed, unless there is a hardware failure to evict.
>>
>> As mentioned in the comments on the previous patch, ttm_bo_evict_first() may return 0 (OK) if it failed to reclaim the
>> trylock in cleanup_refs_and_unlock(), with the assumption that another process will destroy the bo anyway
>> (possibly at a later time which we know nothing about). The lru list needs to be empty when this function returns.
>>
>> This means we must either keep the while(list_empty) or perhaps better, retry instead of WARN if list_empty() is detected at the end of list.
> As long as evict_first returns 0, that function is called over and over again

Ah, ok. You're right.

Reviewed-by: Thomas Hellstrom<thellstrom@vmware.com>