drm/i915: Check the timeout passed to i915_wait_request

We have relied upon the sole caller (wait_ioctl) validating the timeout
argument. However, when waiting for multiple requests I forgot to ensure
that the timeout was still positive on the later requests. This is more
simply done inside __i915_wait_request.

Fixes regression introduced in
commit b47161858ba13c9c7e03333132230d66e008dd55
Author: Chris Wilson <chris@chris-wilson.co.uk>
Date:   Mon Apr 27 13:41:17 2015 +0100

    drm/i915: Implement inter-engine read-read optimisations

The impact of the regression is 1 jiffie for each extra active ring for
a wait_ioctl with a timeout -- I don't think anyone has noticed.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Lionel Landwerlin <lionel.g.landwerlin@linux.intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1448544702-5594-1-git-send-email-chris@chris-wilson.co.uk
Signed-off-by: Jani Nikula <jani.nikula@intel.com>

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 91bb1fc27420f5a58f9fc2ca962a4b452f9cb7e6..32e6aade62238be511237c9ffad1933e18e561cb 100644 (file)
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -1210,8 +1210,16 @@ int __i915_wait_request(struct drm_i915_gem_request *req,
        if (i915_gem_request_completed(req, true))
                return 0;
 
-       timeout_expire = timeout ?
-               jiffies + nsecs_to_jiffies_timeout((u64)*timeout) : 0;
+       timeout_expire = 0;
+       if (timeout) {
+               if (WARN_ON(*timeout < 0))
+                       return -EINVAL;
+
+               if (*timeout == 0)
+                       return -ETIME;
+
+               timeout_expire = jiffies + nsecs_to_jiffies_timeout(*timeout);
+       }
 
        if (INTEL_INFO(dev_priv)->gen >= 6)
                gen6_rps_boost(dev_priv, rps, req->emitted_jiffies);