drm/i915: Use RCU for unlocked vm_idr lookup (aabbe344) · Commits · 戴 / test

Since i915_address_space is now RCU protected, we can do the vm_idr lookup without taking the vm_idr_mutex, just with the rcu_read_lock() instead. Signed-off-by:

Chris Wilson <chris@chris-wilson.co.uk> Reviewed-by:

Matthew Auld <matthew.auld@intel.com> Link: https://patchwork.freedesktop.org/patch/msgid/20190830180325.7755-1-chris@chris-wilson.co.uk

drivers/gpu/drm/i915/gem/i915_gem_context.c

+4 −7

Original line number	Diff line number	Diff line
		@@ -1057,14 +1057,11 @@ static int set_ppgtt(struct drm_i915_file_private *file_priv,
		if (upper_32_bits(args->value))
		return -ENOENT;

		err = mutex_lock_interruptible(&file_priv->vm_idr_lock);
		if (err)
		return err;

		rcu_read_lock();
		vm = idr_find(&file_priv->vm_idr, args->value);
		if (vm)
		i915_vm_get(vm);
		mutex_unlock(&file_priv->vm_idr_lock);
		if (vm && !kref_get_unless_zero(&vm->ref))
		vm = NULL;
		rcu_read_unlock();
		if (!vm)
		return -ENOENT;

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