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Wed, 20 May 2020 12:54:21 +0000 Received: from pps.filterd (userp3020.oracle.com [127.0.0.1]) by userp3020.oracle.com (8.16.0.42/8.16.0.42) with SMTP id 04KCnDV3074147; Wed, 20 May 2020 12:52:21 GMT Received: from userv0121.oracle.com (userv0121.oracle.com [156.151.31.72]) by userp3020.oracle.com with ESMTP id 3150208722-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 20 May 2020 12:52:21 +0000 Received: from abhmp0015.oracle.com (abhmp0015.oracle.com [141.146.116.21]) by userv0121.oracle.com (8.14.4/8.13.8) with ESMTP id 04KCqIYg021917; Wed, 20 May 2020 12:52:18 GMT Received: from kadam (/41.57.98.10) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Wed, 20 May 2020 05:52:17 -0700 Date: Wed, 20 May 2020 15:52:09 +0300 From: Dan Carpenter To: christian.koenig@amd.com Subject: Re: [PATCH] drm/amdgpu: off by on in amdgpu_device_attr_create_groups() error handling Message-ID: <20200520125209.GP3041@kadam> References: <20200520120054.GB172354@mwanda> <62d9d539-8401-233a-3f20-984042489987@gmail.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <62d9d539-8401-233a-3f20-984042489987@gmail.com> User-Agent: Mutt/1.9.4 (2018-02-28) X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9626 signatures=668686 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 spamscore=0 mlxscore=0 mlxlogscore=999 adultscore=0 bulkscore=0 suspectscore=1 phishscore=0 malwarescore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2004280000 definitions=main-2005200110 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9626 signatures=668686 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 adultscore=0 phishscore=0 spamscore=0 bulkscore=0 clxscore=1015 priorityscore=1501 mlxscore=0 impostorscore=0 suspectscore=1 mlxlogscore=999 malwarescore=0 cotscore=-2147483648 lowpriorityscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2004280000 definitions=main-2005200111 X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: David Airlie , Kevin Wang , kernel-janitors@vger.kernel.org, linux-kernel@vger.kernel.org, amd-gfx@lists.freedesktop.org, Rui Huang , dri-devel@lists.freedesktop.org, Alex Deucher , Yintian Tao , Evan Quan , Kenneth Feng , Hawking Zhang Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" On Wed, May 20, 2020 at 02:05:19PM +0200, Christian K=F6nig wrote: > Am 20.05.20 um 14:00 schrieb Dan Carpenter: > > This loop in the error handling code should start a "i - 1" and end at > > "i =3D=3D 0". Currently it starts a "i" and ends at "i =3D=3D 1". The= result > > is that it removes one attribute that wasn't created yet, and leaks the > > zeroeth attribute. > > = > > Fixes: 4e01847c38f7 ("drm/amdgpu: optimize amdgpu device attribute code= ") > > Signed-off-by: Dan Carpenter > > --- > > drivers/gpu/drm/amd/amdgpu/amdgpu_pm.c | 5 ++--- > > 1 file changed, 2 insertions(+), 3 deletions(-) > > = > > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_pm.c b/drivers/gpu/drm/a= md/amdgpu/amdgpu_pm.c > > index b75362bf0742..ee4a8e44fbeb 100644 > > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_pm.c > > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_pm.c > > @@ -1931,7 +1931,7 @@ static int amdgpu_device_attr_create_groups(struc= t amdgpu_device *adev, > > uint32_t mask) > > { > > int ret =3D 0; > > - uint32_t i =3D 0; > > + int i; > > for (i =3D 0; i < counts; i++) { > > ret =3D amdgpu_device_attr_create(adev, &attrs[i], mask); > > @@ -1942,9 +1942,8 @@ static int amdgpu_device_attr_create_groups(struc= t amdgpu_device *adev, > > return 0; > > failed: > > - for (; i > 0; i--) { > > + while (--i >=3D 0) > = > As far as I know the common idiom for this is while (i--) which even works > without changing the type of i to signed. It's about 50/50, one way or the other. To me --i >=3D 0 seems far more readable. I've been trying to figure out which tool tells people to make iterators unsigned so I can help them avoid it. :/ I understand how in theory iterators could go above INT_MAX but if we're going above INT_MAX then probably we should use a 64 bit type. There are very few times where 2 billion iterations is not enough but in those situations probably 4 billion is not enough either. So unsigned int iterators never or seldom solve real life bugs but they regularly cause them. regards, dan carpenter _______________________________________________ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel