From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751834AbcBYVKf (ORCPT ); Thu, 25 Feb 2016 16:10:35 -0500 Received: from mout.kundenserver.de ([212.227.126.130]:64988 "EHLO mout.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751459AbcBYVKe (ORCPT ); Thu, 25 Feb 2016 16:10:34 -0500 From: Arnd Bergmann To: David Airlie Cc: linux-arm-kernel@lists.infradead.org, Arnd Bergmann , dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org Subject: [PATCH, RESEND] drm: avoid uninitialized timestamp use in wait_vblank Date: Thu, 25 Feb 2016 22:09:57 +0100 Message-Id: <1456434600-4185759-1-git-send-email-arnd@arndb.de> X-Mailer: git-send-email 2.7.0 X-Provags-ID: V03:K0:ac8m0o9+mkodd1xNHhJ7GnGZAwpEdwlIPM8qejByuNgSuZV550x LwkmaWxsplBdcKtVzcxOs4k6wLKLGPNWlbawxkpn89zwvUx22T7Md0cUxLPzU0Ln+f8hmxv fcbgM+lzpm3AeAlNfhhruRj3lQS0mQblC66dqiECtv00QgmRrn9w9uAealejhETji/3Rvx+ ydM/CVxrsd+4sYBFozZSQ== X-UI-Out-Filterresults: notjunk:1;V01:K0:JDvzBn7PoHQ=:8dQAlgO+YmLjEmi2IONaOm Eufq3dR8xa0cfPf8xUKI00QSZdbrPgtJMlMTA1qCkUmxC16l5MSOP1Bb9Q30nKcC2PabAoNky XZve6/Tq72unOBQUPd1bwrMx0/DVOoh43RGL2ZB3OQmHTiRib6zMsztbIbqGgZZY4D8yR+v7p caHNs6rg+Udht5rGkm0W0wbW4/Z06XRcQ76aDFgJhfXJSmZn2gXb0ldnKsQ2voEHUwBGiya2r yLGAm1+o3GwAAdCKRMMifTLNVeihkmYzsxwQTcdtCOyk5OMbDaexrk+AGINaROHOL/4cdku54 QU+BtzyMsWjvuyIfyGNpF0utMyBTDrjHczDHs76AiSAozgPXaBa/pDt2tq5Z81e7FgoJPm+nv p/D1UYSN4dJli8J8iEXFk+yEf9DcZGEd0BzLE0ceRMq09/TcsucC8963J4PiVyMo2ZehiwJIP zq1gveVS3ar7MmlKq1Oq3ZOqLAztozvMqZFLSvFtuf9XNTM5jTur2n8NTVoW+9mAnIa+il0MV c1QJ6p6BxmlkkgoTopi9LNPmHG2YKb76Y09wiVMfx/Jdd40A2n+4KrcYD3ralEPT8aelw7d70 DPuTASmmC1jc7Ttk1ykzT+HdSN1XZ0ffdrKwBylKCWhOeoROXq4pGJ/DEgQjvkVDywkjFgD++ WOSPEa1ub2xp6DfA2/IC8cJrieRZTDw3atePPx8aPgOeftfQxm6Z/RLISiRwjuTnteGs= Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org gcc warns about the timestamp in drm_wait_vblank being possibly used without an initialization: drivers/gpu/drm/drm_irq.c: In function 'drm_wait_vblank': drivers/gpu/drm/drm_irq.c:1755:28: warning: 'now.tv_usec' may be used uninitialized in this function [-Wmaybe-uninitialized] vblwait->reply.tval_usec = now.tv_usec; drivers/gpu/drm/drm_irq.c:1754:27: warning: 'now.tv_sec' may be used uninitialized in this function [-Wmaybe-uninitialized] vblwait->reply.tval_sec = now.tv_sec; This can happen if drm_vblank_count_and_time() returns 0 in its error path. To sanitize the error case, I'm changing that function to return a zero timestamp when it fails. Signed-off-by: Arnd Bergmann Fixes: e6ae8687a87b ("drm: idiot-proof vblank") --- drivers/gpu/drm/drm_irq.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) I'm going through the maybe-unused warnings in randconfig builds, this one is apparently not a false positive, although it only happens if something else has already gone wrong. Originally sent out on Jan 13, but I received no reply, so resending now. diff --git a/drivers/gpu/drm/drm_irq.c b/drivers/gpu/drm/drm_irq.c index 881c5a6c180c..6f41ddfbe061 100644 --- a/drivers/gpu/drm/drm_irq.c +++ b/drivers/gpu/drm/drm_irq.c @@ -997,8 +997,10 @@ u32 drm_vblank_count_and_time(struct drm_device *dev, unsigned int pipe, int count = DRM_TIMESTAMP_MAXRETRIES; u32 cur_vblank; - if (WARN_ON(pipe >= dev->num_crtcs)) + if (WARN_ON(pipe >= dev->num_crtcs)) { + *vblanktime = (struct timeval) { 0 }; return 0; + } /* * Vblank timestamps are read lockless. To ensure consistency the vblank -- 2.7.0