Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752855AbaG1PYo (ORCPT ); Mon, 28 Jul 2014 11:24:44 -0400 Received: from mail-wi0-f174.google.com ([209.85.212.174]:40634 "EHLO mail-wi0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751999AbaG1PYn (ORCPT ); Mon, 28 Jul 2014 11:24:43 -0400 Date: Mon, 28 Jul 2014 17:24:48 +0200 From: Daniel Vetter To: Pavel Machek Cc: daniel.vetter@ffwll.ch, jani.nikula@linux.intel.com, airlied@linux.ie, intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] work around warning in i915_gem_gtt Message-ID: <20140728152448.GD4747@phenom.ffwll.local> Mail-Followup-To: Pavel Machek , jani.nikula@linux.intel.com, airlied@linux.ie, intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org References: <20140728112058.GA17504@amd.pavel.ucw.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20140728112058.GA17504@amd.pavel.ucw.cz> X-Operating-System: Linux phenom 3.15.0-rc3+ User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jul 28, 2014 at 01:20:58PM +0200, Pavel Machek wrote: > > Gcc warns that addr might be used uninitialized. It may not, but I see > why gcc gets confused. > > Additionally, hiding code with side-effects inside WARN_ON() argument > seems uncool, so I moved it outside. > > Signed-off-by: Pavel Machek > > diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c b/drivers/gpu/drm/i915/i915_gem_gtt.c > index 8b3cde7..8fcc974 100644 > --- a/drivers/gpu/drm/i915/i915_gem_gtt.c > +++ b/drivers/gpu/drm/i915/i915_gem_gtt.c > @@ -1448,7 +1448,7 @@ static void gen6_ggtt_insert_entries(struct i915_address_space *vm, > (gen6_gtt_pte_t __iomem *)dev_priv->gtt.gsm + first_entry; > int i = 0; > struct sg_page_iter sg_iter; > - dma_addr_t addr; > + dma_addr_t addr = 0; I want to have a /* shuts up gcc */ for these kinds of things, where we need to help out the compiler. Added and merged, thanks. -Daniel > > for_each_sg_page(st->sgl, &sg_iter, st->nents, 0) { > addr = sg_page_iter_dma_address(&sg_iter); > @@ -1462,9 +1462,10 @@ static void gen6_ggtt_insert_entries(struct i915_address_space *vm, > * of NUMA access patterns. Therefore, even with the way we assume > * hardware should work, we must keep this posting read for paranoia. > */ > - if (i != 0) > - WARN_ON(readl(>t_entries[i-1]) != > - vm->pte_encode(addr, level, true)); > + if (i != 0) { > + unsigned long gtt = readl(>t_entries[i-1]); > + WARN_ON(gtt != vm->pte_encode(addr, level, true)); > + } > > /* This next bit makes the above posting read even more important. We > * want to flush the TLBs only after we're certain all the PTE updates > > -- > (english) http://www.livejournal.com/~pavelmachek > (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html > _______________________________________________ > dri-devel mailing list > dri-devel@lists.freedesktop.org > http://lists.freedesktop.org/mailman/listinfo/dri-devel -- Daniel Vetter Software Engineer, Intel Corporation +41 (0) 79 365 57 48 - http://blog.ffwll.ch -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/