Re: [PATCH 3/6] drm/ttm: call ttm_bo_cleanup_refs with reservation and lru lock held, v3

[Thomas Hellstrom <thellstrom@vmware.com>]

On 11/29/2012 12:36 PM, Maarten Lankhorst wrote:
> By removing the unlocking of lru and retaking it immediately, a race is
> removed where the bo is taken off the swap list or the lru list between
> the unlock and relock. As such the cleanup_refs code can be simplified,
> it will attempt to call ttm_bo_wait non-blockingly, and if it fails
> it will drop the locks and perform a blocking wait, or return an error
> if no_wait_gpu was set.
>
> The need for looping is also eliminated, since swapout and evict_mem_first
> will always follow the destruction path, no new fence is allowed
> to be attached. As far as I can see this may already have been the case,
> but the unlocking / relocking required a complicated loop to deal with
> re-reservation.
>
> Changes since v1:
>   - Simplify no_wait_gpu case by folding it in with empty ddestroy.
>   - Hold a reservation while calling ttm_bo_cleanup_memtype_use again.
> Changes since v2:
>   - Do not remove bo from lru list while waiting
>
> Signed-off-by: Maarten Lankhorst <maarten.lankhorst@canonical.com>

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