From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 14BA0CCD1BE for ; Wed, 18 Sep 2024 15:05:48 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 8E28410E5E1; Wed, 18 Sep 2024 15:05:47 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (2048-bit key; unprotected) header.d=kernel.org header.i=@kernel.org header.b="fi1GILGD"; dkim-atps=neutral Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by gabe.freedesktop.org (Postfix) with ESMTPS id C860F10E5D9; Wed, 18 Sep 2024 15:05:45 +0000 (UTC) Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by dfw.source.kernel.org (Postfix) with ESMTP id 5389C5C0643; Wed, 18 Sep 2024 15:05:41 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 41C37C4CEC2; Wed, 18 Sep 2024 15:05:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1726671944; bh=NEbsoDGarkF9DcJ1oPB0XKgElHrM+/7uFjvxWCETW0Q=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=fi1GILGDGqdRw5CBleFgjz4TidR4S1TdejI62SRowk6vuJvj9pjXHpSAGdlPfuI1M c3oeEEdj1SqjpjawyCLABhDqu1sCnDS+03+xoA9DYwRWke5QOxrKvgrb+NF/fYtMsY VIFXPeamYNM2JkxHyIaU6Nil5kCJ8iYR+Iv9rNBh7BCaujHbYFPWR64ho6UDyUrYsT 9ckVpjAZHZVEqjv9mYDoOZXB1Xlag32yFPdhICgUt8BNTKeqYMYHlaQr17xMflUtaf 8/vEFafIFhm2kX5+RPV1NTouAhBw/rsvEdF4mDTTC/ita6U5rdLUV5bviZlp7H4KZO KkWckROIB9C4w== Date: Wed, 18 Sep 2024 08:05:42 -0700 From: Nathan Chancellor To: Jani Nikula Cc: intel-gfx@lists.freedesktop.org, intel-xe@lists.freedesktop.org, Matthew Auld , Rodrigo Vivi , Anshuman Gupta , Andi Shyti , stable@vger.kernel.org Subject: Re: [PATCH 1/5] drm/i915/gem: fix bitwise and logical AND mixup Message-ID: <20240918150542.GA4049109@thelio-3990X> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-BeenThere: intel-xe@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Intel Xe graphics driver List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: intel-xe-bounces@lists.freedesktop.org Sender: "Intel-xe" On Wed, Sep 18, 2024 at 02:17:44PM +0300, Jani Nikula wrote: > CONFIG_DRM_I915_USERFAULT_AUTOSUSPEND is an int, defaulting to 250. When > the wakeref is non-zero, it's either -1 or a dynamically allocated > pointer, depending on CONFIG_DRM_I915_DEBUG_RUNTIME_PM. It's likely that > the code works by coincidence with the bitwise AND, but with > CONFIG_DRM_I915_DEBUG_RUNTIME_PM=y, there's the off chance that the > condition evaluates to false, and intel_wakeref_auto() doesn't get > called. Switch to the intended logical AND. > > Fixes: ad74457a6b5a ("drm/i915/dgfx: Release mmap on rpm suspend") > Cc: Matthew Auld > Cc: Rodrigo Vivi > Cc: Anshuman Gupta > Cc: Andi Shyti > Cc: # v6.1+ > Signed-off-by: Jani Nikula > --- > drivers/gpu/drm/i915/gem/i915_gem_ttm.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/i915/gem/i915_gem_ttm.c b/drivers/gpu/drm/i915/gem/i915_gem_ttm.c > index 5c72462d1f57..c157ade48c39 100644 > --- a/drivers/gpu/drm/i915/gem/i915_gem_ttm.c > +++ b/drivers/gpu/drm/i915/gem/i915_gem_ttm.c > @@ -1131,7 +1131,7 @@ static vm_fault_t vm_fault_ttm(struct vm_fault *vmf) > GEM_WARN_ON(!i915_ttm_cpu_maps_iomem(bo->resource)); > } > > - if (wakeref & CONFIG_DRM_I915_USERFAULT_AUTOSUSPEND) > + if (wakeref && CONFIG_DRM_I915_USERFAULT_AUTOSUSPEND) This is going to result in a clang warning: drivers/gpu/drm/i915/gem/i915_gem_ttm.c:1134:14: error: use of logical '&&' with constant operand [-Werror,-Wconstant-logical-operand] 1134 | if (wakeref && CONFIG_DRM_I915_USERFAULT_AUTOSUSPEND) | ^ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ drivers/gpu/drm/i915/gem/i915_gem_ttm.c:1134:14: note: use '&' for a bitwise operation 1134 | if (wakeref && CONFIG_DRM_I915_USERFAULT_AUTOSUSPEND) | ^~ | & drivers/gpu/drm/i915/gem/i915_gem_ttm.c:1134:14: note: remove constant to silence this warning 1134 | if (wakeref && CONFIG_DRM_I915_USERFAULT_AUTOSUSPEND) | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1 error generated. Consider adding the explicit '!= 0' to make it clear this should be a boolean expression. Cheers, Nathan > intel_wakeref_auto(&to_i915(obj->base.dev)->runtime_pm.userfault_wakeref, > msecs_to_jiffies_timeout(CONFIG_DRM_I915_USERFAULT_AUTOSUSPEND)); > > -- > 2.39.2 >