From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Laight Subject: RE: [PATCH AUTOSEL 5.2 51/59] drm/exynos: fix missing decrement of retry counter Date: Wed, 7 Aug 2019 08:49:52 +0000 Message-ID: <2ecde45912fc44b88df2ff5129b8ab67@AcuMS.aculab.com> References: <20190806213319.19203-1-sashal@kernel.org> <20190806213319.19203-51-sashal@kernel.org> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Return-path: In-Reply-To: <20190806213319.19203-51-sashal@kernel.org> Content-Language: en-US Sender: stable-owner@vger.kernel.org To: 'Sasha Levin' , "linux-kernel@vger.kernel.org" , "stable@vger.kernel.org" Cc: Colin Ian King , Inki Dae , "dri-devel@lists.freedesktop.org" List-Id: dri-devel@lists.freedesktop.org From: Sasha Levin > Sent: 06 August 2019 22:33 > > From: Colin Ian King > > [ Upstream commit 1bbbab097a05276e312dd2462791d32b21ceb1ee ] > > Currently the retry counter is not being decremented, leading to a > potential infinite spin if the scalar_reads don't change state. > > Addresses-Coverity: ("Infinite loop") > Fixes: 280e54c9f614 ("drm/exynos: scaler: Reset hardware before starting the operation") > Signed-off-by: Colin Ian King > Signed-off-by: Inki Dae > Signed-off-by: Sasha Levin > --- > drivers/gpu/drm/exynos/exynos_drm_scaler.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/drivers/gpu/drm/exynos/exynos_drm_scaler.c b/drivers/gpu/drm/exynos/exynos_drm_scaler.c > index ec9c1b7d31033..8989f8af716b7 100644 > --- a/drivers/gpu/drm/exynos/exynos_drm_scaler.c > +++ b/drivers/gpu/drm/exynos/exynos_drm_scaler.c > @@ -94,12 +94,12 @@ static inline int scaler_reset(struct scaler_context *scaler) > scaler_write(SCALER_CFG_SOFT_RESET, SCALER_CFG); > do { > cpu_relax(); > - } while (retry > 1 && > + } while (--retry > 1 && > scaler_read(SCALER_CFG) & SCALER_CFG_SOFT_RESET); > do { > cpu_relax(); > scaler_write(1, SCALER_INT_EN); > - } while (retry > 0 && scaler_read(SCALER_INT_EN) != 1); > + } while (--retry > 0 && scaler_read(SCALER_INT_EN) != 1); > > return retry ? 0 : -EIO; If the first loop hits the retry limit the second loop won't be right and the final return value will be 0. David - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales)