This very much looks like copypasta from drm/i915's fault handler. It was used there to duct-tape over issues around gpu reset handling.

Since that can't ever happen for udl and there's seemingly no other reason for this just drop it.

Reported-by: Peter Zijlstra peterz@infradead.org Cc: Peter Zijlstra peterz@infradead.org Cc: Linux Kernel Mailing List linux-kernel@vger.kernel.org Cc: Dave Airlie airlied@linux.ie Signed-off-by: Daniel Vetter daniel.vetter@ffwll.ch --- drivers/gpu/drm/udl/udl_gem.c | 1 - 1 file changed, 1 deletion(-)

diff --git a/drivers/gpu/drm/udl/udl_gem.c b/drivers/gpu/drm/udl/udl_gem.c index 8dbe9d0..8bf6461 100644 --- a/drivers/gpu/drm/udl/udl_gem.c +++ b/drivers/gpu/drm/udl/udl_gem.c @@ -97,7 +97,6 @@ int udl_gem_fault(struct vm_area_struct *vma, struct vm_fault *vmf) ret = vm_insert_page(vma, (unsigned long)vmf->virtual_address, page); switch (ret) { case -EAGAIN: - set_need_resched(); case 0: case -ERESTARTSYS: return VM_FAULT_NOPAGE;

hmm, looks like I cargo-cult'd the same into msm.

I guess in i915 (and ttm) case, the issue arises due to need for CPU access to buffer via GTT? In which case I should be safe to drop the set_need_resched() as well? (Since CPU always has direct access to the pages.) Or am I missing something about the original issue that necessitated set_need_resched()?

BR, -R

On Thu, Sep 12, 2013 at 11:57 AM, Daniel Vetter daniel.vetter@ffwll.ch wrote:

This is just a remnant from the old days when our reset handling was horribly racy, suffered from terribly locking issues and often happily live-locked. Those days are now gone so we can drop the hacks and just rip the reschedule-point out.

Reported-by: Peter Zijlstra peterz@infradead.org Cc: Peter Zijlstra peterz@infradead.org Cc: Linux Kernel Mailing List linux-kernel@vger.kernel.org Signed-off-by: Daniel Vetter daniel.vetter@ffwll.ch

---

drivers/gpu/drm/i915/i915_gem.c | 11 ++++------- 1 file changed, 4 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c index d80f33d..3871060 100644 --- a/drivers/gpu/drm/i915/i915_gem.c +++ b/drivers/gpu/drm/i915/i915_gem.c @@ -1389,14 +1389,11 @@ out: if (i915_terminally_wedged(&dev_priv->gpu_error)) return VM_FAULT_SIGBUS; case -EAGAIN:

•           /* Give the error handler a chance to run and move the
  

•            * objects off the GPU active list. Next time we service the
  

•            * fault, we should be able to transition the page into the
  

•            * GTT without touching the GPU (and so avoid further
  

•            * EIO/EGAIN). If the GPU is wedged, then there is no issue
  

•            * with coherency, just lost writes.
  

•           /*
  

•            * EAGAIN means the gpu is hung and we'll wait for the error
  

•            * handler to reset everything when re-faulting in
  

•            * i915_mutex_lock_interruptible.
             */
  

•           set_need_resched();
    case 0:
    case -ERESTARTSYS:
    case -EINTR:
  

-- 1.8.4.rc3

---

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