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Fri, 24 Jan 2020 10:32:40 +0000 Received: from pps.filterd (aserp3020.oracle.com [127.0.0.1]) by aserp3020.oracle.com (8.16.0.27/8.16.0.27) with SMTP id 00OAWO3t102935; Fri, 24 Jan 2020 10:32:39 GMT Received: from userv0121.oracle.com (userv0121.oracle.com [156.151.31.72]) by aserp3020.oracle.com with ESMTP id 2xqmwe85tq-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Fri, 24 Jan 2020 10:32:39 +0000 Received: from abhmp0002.oracle.com (abhmp0002.oracle.com [141.146.116.8]) by userv0121.oracle.com (8.14.4/8.13.8) with ESMTP id 00OAVY4T023294; Fri, 24 Jan 2020 10:31:35 GMT Received: from kadam (/129.205.23.165) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Fri, 24 Jan 2020 02:31:33 -0800 Date: Fri, 24 Jan 2020 13:31:23 +0300 From: Dan Carpenter To: Chris Wilson Cc: Sumit Semwal , Gustavo Padovan , Sean Paul , linux-media@vger.kernel.org, dri-devel@lists.freedesktop.org, linaro-mm-sig@lists.linaro.org, kernel-janitors@vger.kernel.org Subject: Re: [PATCH] dma-buf: fix locking in sync_print_obj() Message-ID: <20200124103123.GL1847@kadam> References: <20200124101311.drryaegcdc7d4x7e@kili.mountain> <157986125623.2524.13979010293671565726@skylake-alporthouse-com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <157986125623.2524.13979010293671565726@skylake-alporthouse-com> User-Agent: Mutt/1.9.4 (2018-02-28) X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9509 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=0 malwarescore=0 phishscore=0 bulkscore=0 spamscore=0 mlxscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1911140001 definitions=main-2001240086 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9509 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1911140001 definitions=main-2001240086 Sender: linux-media-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-media@vger.kernel.org On Fri, Jan 24, 2020 at 10:20:56AM +0000, Chris Wilson wrote: > Quoting Dan Carpenter (2020-01-24 10:13:12) > > This is always called with IRQs disabled and we don't actually want to > > enable IRQs at the end. > > > > Fixes: a6aa8fca4d79 ("dma-buf/sw-sync: Reduce irqsave/irqrestore from known context") > > Signed-off-by: Dan Carpenter > > --- > > drivers/dma-buf/sync_debug.c | 5 +++-- > > 1 file changed, 3 insertions(+), 2 deletions(-) > > > > diff --git a/drivers/dma-buf/sync_debug.c b/drivers/dma-buf/sync_debug.c > > index 101394f16930..952331344b1c 100644 > > --- a/drivers/dma-buf/sync_debug.c > > +++ b/drivers/dma-buf/sync_debug.c > > @@ -107,15 +107,16 @@ static void sync_print_fence(struct seq_file *s, > > static void sync_print_obj(struct seq_file *s, struct sync_timeline *obj) > > { > > struct list_head *pos; > > + unsigned long flags; > > > > seq_printf(s, "%s: %d\n", obj->name, obj->value); > > > > - spin_lock_irq(&obj->lock); > > + spin_lock_irqsave(&obj->lock, flags); > > Exactly, it can be just spin_lock() as the irq state is known. > I did consider that but I wasn't sure how this is going to be used in the future so I took a conservative approach. > Once again I question why this [sync_debug.c] code even exists. No idea. regards, dan carpenter