From: Eric Anholt <eric@anholt.net>
Date: Mon, 9 Mar 2009 16:42:23 +0000 (-0700)
Subject: drm/i915: Fix lock order reversal in GTT pwrite path.
X-Git-Tag: v2.6.30-rc1~646^2~20
X-Git-Url: https://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=3de09aa3b38910d366f4710ffdf430c9d387d1a3;p=pandora-kernel.git

drm/i915: Fix lock order reversal in GTT pwrite path.

Since the pagefault path determines that the lock order we use has to be
mmap_sem -> struct_mutex, we can't allow page faults to occur while the
struct_mutex is held.  To fix this in pwrite, we first try optimistically to
see if we can copy from user without faulting.  If it fails, fall back to
using get_user_pages to pin the user's memory, and map those pages
atomically when copying it to the GPU.

Signed-off-by: Eric Anholt <eric@anholt.net>
Reviewed-by: Jesse Barnes <jbarnes@virtuousgeek.org>
---

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