void
rw_exit_write(struct rwlock *rwl)
{
unsigned long owner = rwl->rwl_owner;
rw_assert_wrlock(rwl);
if (__predict_false((owner & RWLOCK_WAIT) ||
rw_cas(&rwl->rwl_owner, owner, 0)))
rw_exit(rwl);
}
/**
* The default context needs to exist per ring that uses contexts. It stores the
* context state of the GPU for applications that don't utilize HW contexts, as
* well as an idle case.
*/
static int create_default_context(struct drm_i915_private *dev_priv)
{
struct i915_hw_context *ctx;
struct drm_device *dev = (struct drm_device *)dev_priv->drmdev;
int ret;
rw_assert_wrlock(&dev->dev_lock);
ctx = create_hw_context(dev, NULL);
if (IS_ERR(ctx))
return PTR_ERR(ctx);
/* We may need to do things with the shrinker which require us to
* immediately switch back to the default context. This can cause a
* problem as pinning the default context also requires GTT space which
* may not be available. To avoid this we always pin the
* default context.
*/
dev_priv->ring[RCS].default_context = ctx;
ret = i915_gem_object_pin(ctx->obj, CONTEXT_ALIGN, false, false);
if (ret)
goto err_destroy;
ret = do_switch(ctx);
if (ret)
goto err_unpin;
DRM_DEBUG_DRIVER("Default HW context loaded\n");
return 0;
err_unpin:
i915_gem_object_unpin(ctx->obj);
err_destroy:
do_destroy(ctx);
return ret;
}
void
rw_exit(struct rwlock *rwl)
{
unsigned long owner = rwl->rwl_owner;
int wrlock = owner & RWLOCK_WRLOCK;
unsigned long set;
if (wrlock)
rw_assert_wrlock(rwl);
else
rw_assert_rdlock(rwl);
do {
owner = rwl->rwl_owner;
if (wrlock)
set = 0;
else
set = (owner - RWLOCK_READ_INCR) &
~(RWLOCK_WAIT|RWLOCK_WRWANT);
} while (rw_cas(&rwl->rwl_owner, owner, set));
if (owner & RWLOCK_WAIT)
wakeup(rwl);
}
