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[95.92.181.29]) by smtp.gmail.com with ESMTPSA id v18sm4965760wru.85.2021.03.24.15.00.14 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 24 Mar 2021 15:00:14 -0700 (PDT) Date: Wed, 24 Mar 2021 19:00:08 -0300 From: Melissa Wen To: Dmitry Vyukov Cc: daniel@ffwll.ch, airlied@linux.ie, hamohammed.sa@gmail.com, rodrigosiqueiramelo@gmail.com, syzbot+4fc21a003c8332eb0bdd@syzkaller.appspotmail.com, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] drm/vkms: fix misuse of WARN_ON Message-ID: <20210324220008.nqwwwfugyfngbn3x@smtp.gmail.com> References: <20210320132840.1315853-1-dvyukov@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210320132840.1315853-1-dvyukov@google.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 03/20, Dmitry Vyukov wrote: > vkms_vblank_simulate() uses WARN_ON for timing-dependent condition > (timer overrun). This is a mis-use of WARN_ON, WARN_ON must be used > to denote kernel bugs. Use pr_warn() instead. > > Signed-off-by: Dmitry Vyukov > Reported-by: syzbot+4fc21a003c8332eb0bdd@syzkaller.appspotmail.com > Cc: Rodrigo Siqueira > Cc: Melissa Wen > Cc: Haneen Mohammed > Cc: Daniel Vetter > Cc: David Airlie > Cc: dri-devel@lists.freedesktop.org > Cc: linux-kernel@vger.kernel.org > Change-Id: I7f01c288092bc7e472ec63af198f93ce3d8c49f7 > --- > drivers/gpu/drm/vkms/vkms_crtc.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/vkms/vkms_crtc.c b/drivers/gpu/drm/vkms/vkms_crtc.c > index 0443b7deeaef6..758d8a98d96b3 100644 > --- a/drivers/gpu/drm/vkms/vkms_crtc.c > +++ b/drivers/gpu/drm/vkms/vkms_crtc.c > @@ -18,7 +18,8 @@ static enum hrtimer_restart vkms_vblank_simulate(struct hrtimer *timer) > > ret_overrun = hrtimer_forward_now(&output->vblank_hrtimer, > output->period_ns); > - WARN_ON(ret_overrun != 1); > + if (ret_overrun != 1) > + pr_warn("%s: vblank timer overrun\n", __func__); Hi Dmitry, Thanks for your patch. Looks good to me. The Change-Id tag just seems a little noisy to me, but can be fixed while applying. Acked-by: Melissa Wen > > spin_lock(&output->lock); > ret = drm_crtc_handle_vblank(crtc); > > base-commit: e94c55b8e0a0bbe9a026250cf31e2fa45957d776 > -- > 2.31.0.291.g576ba9dcdaf-goog >