From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755124Ab2LGOyo (ORCPT ); Fri, 7 Dec 2012 09:54:44 -0500 Received: from mail.tpi.com ([70.99.223.143]:2991 "EHLO mail.tpi.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751469Ab2LGOyn (ORCPT ); Fri, 7 Dec 2012 09:54:43 -0500 From: Tim Gardner To: jani.nikula@linux.intel.com, linux-kernel@vger.kernel.org Cc: Tim Gardner , Daniel Vetter , David Airlie , dri-devel@lists.freedesktop.org Subject: [PATCH v2 linux-next] i915: intel_set_mode: Reduce stack allocation from 500 bytes to 2 pointers Date: Fri, 7 Dec 2012 07:54:26 -0700 Message-Id: <1354892066-30256-1-git-send-email-tim.gardner@canonical.com> X-Mailer: git-send-email 1.7.9.5 In-Reply-To: <87zk1qm6cd.fsf@intel.com> References: <87zk1qm6cd.fsf@intel.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org smatch warning: drivers/gpu/drm/i915/intel_display.c:7019 intel_set_mode() warn: function puts 500 bytes on stack Refactor so that saved_mode and saved_hwmode are dynamically allocated as opposed to being automatic variables. 500 bytes seems like it could run the potential for blowing the kernel stack. Cc: Daniel Vetter Cc: David Airlie Cc: dri-devel@lists.freedesktop.org Signed-off-by: Tim Gardner --- V2 - spaces around '*', use kmalloc instead of kzalloc(). Missed error return that would have orphaned memory. drivers/gpu/drm/i915/intel_display.c | 22 ++++++++++++++++------ 1 file changed, 16 insertions(+), 6 deletions(-) diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c index de51489..c15b21b 100644 --- a/drivers/gpu/drm/i915/intel_display.c +++ b/drivers/gpu/drm/i915/intel_display.c @@ -7739,11 +7739,18 @@ bool intel_set_mode(struct drm_crtc *crtc, { struct drm_device *dev = crtc->dev; drm_i915_private_t *dev_priv = dev->dev_private; - struct drm_display_mode *adjusted_mode, saved_mode, saved_hwmode; + struct drm_display_mode *adjusted_mode, *saved_mode, *saved_hwmode; struct intel_crtc *intel_crtc; unsigned disable_pipes, prepare_pipes, modeset_pipes; bool ret = true; + saved_mode = kmalloc(2 * sizeof(*saved_mode), GFP_KERNEL); + if (!saved_mode) { + DRM_ERROR("i915: Could not allocate saved display mode.\n"); + return false; + } + saved_hwmode = saved_mode + 1; + intel_modeset_affected_pipes(crtc, &modeset_pipes, &prepare_pipes, &disable_pipes); @@ -7753,8 +7760,8 @@ bool intel_set_mode(struct drm_crtc *crtc, for_each_intel_crtc_masked(dev, disable_pipes, intel_crtc) intel_crtc_disable(&intel_crtc->base); - saved_hwmode = crtc->hwmode; - saved_mode = crtc->mode; + *saved_hwmode = crtc->hwmode; + *saved_mode = crtc->mode; /* Hack: Because we don't (yet) support global modeset on multiple * crtcs, we don't keep track of the new mode for more than one crtc. @@ -7765,7 +7772,8 @@ bool intel_set_mode(struct drm_crtc *crtc, if (modeset_pipes) { adjusted_mode = intel_modeset_adjusted_mode(crtc, mode); if (IS_ERR(adjusted_mode)) { - return false; + ret = false; + goto out; } } @@ -7817,12 +7825,14 @@ bool intel_set_mode(struct drm_crtc *crtc, done: drm_mode_destroy(dev, adjusted_mode); if (!ret && crtc->enabled) { - crtc->hwmode = saved_hwmode; - crtc->mode = saved_mode; + crtc->hwmode = *saved_hwmode; + crtc->mode = *saved_mode; } else { intel_modeset_check_state(dev); } +out: + kfree(saved_mode); return ret; } -- 1.7.9.5