From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8C3CAC433EF for ; Tue, 26 Oct 2021 11:52:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6B26C60F39 for ; Tue, 26 Oct 2021 11:52:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235582AbhJZLzL (ORCPT ); Tue, 26 Oct 2021 07:55:11 -0400 Received: from mailgw01.mediatek.com ([60.244.123.138]:49868 "EHLO mailgw01.mediatek.com" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S235563AbhJZLzJ (ORCPT ); Tue, 26 Oct 2021 07:55:09 -0400 X-UUID: 85655ae7c4df4c47993a373fa7dca3e1-20211026 X-UUID: 85655ae7c4df4c47993a373fa7dca3e1-20211026 Received: from mtkexhb02.mediatek.inc [(172.21.101.103)] by mailgw01.mediatek.com (envelope-from ) (Generic MTA with TLSv1.2 ECDHE-RSA-AES256-SHA384 256/256) with ESMTP id 592306941; Tue, 26 Oct 2021 19:52:43 +0800 Received: from mtkcas11.mediatek.inc (172.21.101.40) by mtkmbs10n1.mediatek.inc (172.21.101.34) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384) id 15.2.792.15; Tue, 26 Oct 2021 19:52:41 +0800 Received: from mszswglt01.gcn.mediatek.inc (10.16.20.20) by mtkcas11.mediatek.inc (172.21.101.73) with Microsoft SMTP Server id 15.0.1497.2 via Frontend Transport; Tue, 26 Oct 2021 19:52:41 +0800 From: To: CC: , , , , , , , , , , , Guangming Cao Subject: Re: [PATCH v3] dma-buf: remove restriction of IOCTL:DMA_BUF_SET_NAME Date: Tue, 26 Oct 2021 19:52:48 +0800 Message-ID: <20211026115248.9564-1-guangming.cao@mediatek.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <0e062f12-7e79-5a05-1e7b-10dda8e353b7@amd.com> References: <0e062f12-7e79-5a05-1e7b-10dda8e353b7@amd.com> MIME-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8bit X-MTK: N Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Guangming Cao On Tue, 2021-10-26 at 13:18 +0200, Christian König wrote: > Am 14.10.21 um 12:25 schrieb guangming.cao@mediatek.com: > > From: Guangming Cao > > > > In this patch(https://patchwork.freedesktop.org/patch/310349), > > it add a new IOCTL to support dma-buf user to set debug name. > > > > But it also added a limitation of this IOCTL, it needs the > > attachments of dmabuf should be empty, otherwise it will fail. > > > > For the original series, the idea was that allowing name change > > mid-use could confuse the users about the dma-buf. > > However, the rest of the series also makes sure each dma-buf have a > > unique > > inode(https://patchwork.freedesktop.org/patch/310387/), and any > > accounting > > should probably use that, without relying on the name as much. > > > > So, removing this restriction will let dma-buf userspace users to > > use it > > more comfortably and without any side effect. > > > > Signed-off-by: Guangming Cao > > We could now cleanup the return value from dma_buf_set_name() into a > void since that function can't fail any more as far as I can see. > > But that isn't mandatory I think, patch is Reviewed-by: Christian > König > > So, here is no need to check return value of 'strndup_user', just return without error code if the almost impossible error occurs? Guangming. > Regards, > Christian. > > > --- > > drivers/dma-buf/dma-buf.c | 17 +++-------------- > > 1 file changed, 3 insertions(+), 14 deletions(-) > > > > diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c > > index 511fe0d217a0..5fbb3a2068a3 100644 > > --- a/drivers/dma-buf/dma-buf.c > > +++ b/drivers/dma-buf/dma-buf.c > > @@ -325,10 +325,8 @@ static __poll_t dma_buf_poll(struct file > > *file, poll_table *poll) > > > > /** > > * dma_buf_set_name - Set a name to a specific dma_buf to track > > the usage. > > - * The name of the dma-buf buffer can only be set when the dma-buf > > is not > > - * attached to any devices. It could theoritically support > > changing the > > - * name of the dma-buf if the same piece of memory is used for > > multiple > > - * purpose between different devices. > > + * It could support changing the name of the dma-buf if the same > > + * piece of memory is used for multiple purpose between different > > devices. > > * > > * @dmabuf: [in] dmabuf buffer that will be renamed. > > * @buf: [in] A piece of userspace memory that contains > > the name of > > @@ -341,25 +339,16 @@ static __poll_t dma_buf_poll(struct file > > *file, poll_table *poll) > > static long dma_buf_set_name(struct dma_buf *dmabuf, const char > > __user *buf) > > { > > char *name = strndup_user(buf, DMA_BUF_NAME_LEN); > > - long ret = 0; > > > > if (IS_ERR(name)) > > return PTR_ERR(name); > > > > - dma_resv_lock(dmabuf->resv, NULL); > > - if (!list_empty(&dmabuf->attachments)) { > > - ret = -EBUSY; > > - kfree(name); > > - goto out_unlock; > > - } > > spin_lock(&dmabuf->name_lock); > > kfree(dmabuf->name); > > dmabuf->name = name; > > spin_unlock(&dmabuf->name_lock); > > > > -out_unlock: > > - dma_resv_unlock(dmabuf->resv); > > - return ret; > > + return 0; > > } > > > > static long dma_buf_ioctl(struct file *file, > >