From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Google-Smtp-Source: AG47ELvZJL2E6QUyhnYsoaYf/FIkkxgw/BgkL12oyVytLKjYDgJ9MLprFJiLEzHsJ/4XKeaS5TPu ARC-Seal: i=1; a=rsa-sha256; t=1520933991; cv=none; d=google.com; s=arc-20160816; b=xmzErhtkl4Z9eE0ZRqLw10uSkK6mXZ0LY2wyr4VJP8iYpDat3hpRddd19hPvspN7Sr 6v4i1ZC1HqZjegm9aLM7ILRWysrZCtt5rfyTS0ULGBzeiXdgAwhSpl16sru2L4mPjENU Zw98caZwLOI1lINT1CzPNnE0bPd05j2baESIxibMWGPCoGLzZSo4J14sMEiesBf/Rsp3 66L1pZFWA3O5iBfj59keWq6uOHOAIdp/L6FNrM5B3aUQuaW08dDlM8H+7/hZbqnR96RY 6C3qWXEH9PF1A5h1tbYsrhb0lHbRHoI0GL99zndiO7tfefUxXUjyXhqmM9esjepBnSUX 2NLA== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:arc-authentication-results; bh=QWbK8WpUxSJzqR3+i43mX1HR9b6GZmUo7JfJAtbVAnU=; b=TFLOAo2L4qam6/ejtPn4nnx7ubEu1HMRARrEAM3e1zK7Zohm9/ahIFrk1Q475f4tpB Y3/WyKZnbErotcupP5RQkmDI2fZsH+m0+Dw1AislKb7SDNFmU+PIvA2vXcv9PZGEGCSA PS25pNN0mmfGSkhrS+v0XqO+7LN+3g1UpxGpd124Y6+ZfZQbbsYy1YSSzBZICLjA3tlk r5e6k1xFaBiP4KM7RwlDCZp7E0YCJizKyp7FEMBxBGnMFEjPwOWeec7AZvUUWiXqQ+rp 2MHpvpUs4mGTDvHFURb3r/boH0vvonAANp9cZTyFw7Hh5oyizxBX0xWCGe8seLYfYlVY dbzQ== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: domain of rjw@rjwysocki.net designates 79.96.170.134 as permitted sender) smtp.mailfrom=rjw@rjwysocki.net Authentication-Results: mx.google.com; spf=pass (google.com: domain of rjw@rjwysocki.net designates 79.96.170.134 as permitted sender) smtp.mailfrom=rjw@rjwysocki.net From: "Rafael J. Wysocki" To: Vivek Gautam Cc: joro@8bytes.org, robh+dt@kernel.org, robin.murphy@arm.com, iommu@lists.linux-foundation.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, mark.rutland@arm.com, will.deacon@arm.com, robdclark@gmail.com, tfiga@chromium.org, sricharan@codeaurora.org, m.szyprowski@samsung.com, architt@codeaurora.org, linux-arm-msm@vger.kernel.org, Greg Kroah-Hartman Subject: Re: [PATCH v9 1/5] driver core: Find an existing link between two devices Date: Tue, 13 Mar 2018 10:40:26 +0100 Message-ID: <8903307.QazHKW0JrR@aspire.rjw.lan> In-Reply-To: <20180313085534.11650-2-vivek.gautam@codeaurora.org> References: <20180313085534.11650-1-vivek.gautam@codeaurora.org> <20180313085534.11650-2-vivek.gautam@codeaurora.org> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: =?utf-8?q?1594812129788829883?= X-GMAIL-MSGID: =?utf-8?q?1594814881294873136?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: On Tuesday, March 13, 2018 9:55:30 AM CET Vivek Gautam wrote: > The lists managing the device-links can be traversed to > find the link between two devices. The device_link_add() APIs > does traverse these lists to check if there's already a link > setup between the two devices. > So, add a new APIs, device_link_find(), to find an existing > device link between two devices - suppliers and consumers. > > Signed-off-by: Vivek Gautam > Cc: Rafael J. Wysocki > Cc: Greg Kroah-Hartman > --- > > * New patch added to this series. > > drivers/base/core.c | 30 +++++++++++++++++++++++++++--- > include/linux/device.h | 2 ++ > 2 files changed, 29 insertions(+), 3 deletions(-) > > diff --git a/drivers/base/core.c b/drivers/base/core.c > index 5847364f25d9..e8c9774e4ba2 100644 > --- a/drivers/base/core.c > +++ b/drivers/base/core.c > @@ -144,6 +144,30 @@ static int device_reorder_to_tail(struct device *dev, void *not_used) > return 0; > } > > +/** > + * device_link_find - find any existing link between two devices. > + * @consumer: Consumer end of the link. > + * @supplier: Supplier end of the link. > + * > + * Returns pointer to the existing link between a supplier and > + * and consumer devices, or NULL if no link exists. > + */ > +struct device_link *device_link_find(struct device *consumer, > + struct device *supplier) > +{ > + struct device_link *link = NULL; > + > + if (!consumer || !supplier) > + return NULL; > + > + list_for_each_entry(link, &supplier->links.consumers, s_node) > + if (link->consumer == consumer) > + break; > + Any mutual exclusion? Or is the caller expected to take care of it? And if so, then how? > + return link; > +} > +EXPORT_SYMBOL_GPL(device_link_find); > + > /** > * device_link_add - Create a link between two devices. > * @consumer: Consumer end of the link. > @@ -195,9 +219,9 @@ struct device_link *device_link_add(struct device *consumer, > goto out; > } > > - list_for_each_entry(link, &supplier->links.consumers, s_node) > - if (link->consumer == consumer) > - goto out; > + link = device_link_find(consumer, supplier); > + if (link) > + goto out; > > link = kzalloc(sizeof(*link), GFP_KERNEL); > if (!link) > diff --git a/include/linux/device.h b/include/linux/device.h > index b093405ed525..13bc1884c3eb 100644 > --- a/include/linux/device.h > +++ b/include/linux/device.h > @@ -1278,6 +1278,8 @@ extern const char *dev_driver_string(const struct device *dev); > struct device_link *device_link_add(struct device *consumer, > struct device *supplier, u32 flags); > void device_link_del(struct device_link *link); > +struct device_link *device_link_find(struct device *consumer, > + struct device *supplier); > > #ifdef CONFIG_PRINTK > >