Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Date:   Wed, 20 Nov 2019 19:02:29 +0100
From:   Luc Van Oostenryck <luc.vanoostenryck@gmail.com>
To:     Dragan Cvetic <draganc@xilinx.com>
Cc:     "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Derek Kiernan <dkiernan@xilinx.com>
Subject: Re: [PATCH] misc: xilinx_sdfec: fix xsdfec_poll()'s return type
Message-ID: <20191120180229.frd5padrsdxf7hag@ltop.local>
References: <20191120001030.30779-1-luc.vanoostenryck@gmail.com>
 <CH2PR02MB6359CE45D06E908634CDA855CB4F0@CH2PR02MB6359.namprd02.prod.outlook.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <CH2PR02MB6359CE45D06E908634CDA855CB4F0@CH2PR02MB6359.namprd02.prod.outlook.com>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Wed, Nov 20, 2019 at 03:59:24PM +0000, Dragan Cvetic wrote:
> Hi Luc,
> 
> For the sake of my understanding I'd like to ask you when the .pole method is defined 
> Why I'm asking this? I have a fairly new book (published in 2017) which suggests what is implemented in SDFEC driver.
> 
> I'll test your suggestions and will come back to you soon.

Well, yes, it changed in July 2017.

The current definition can be found in include/linux/fs.h:
	struct file_operations {
		...
		__poll_t (*poll) (struct file *, struct poll_table_struct *);
		...

The main commit making the change is:
    a3f8683bf7d5 ("->poll() methods should return __poll_t")


The result can be verified by compiling the driver with the command
	make C=2 path/to/the/driver.o
which will use the static analyser 'sparse' to make additional checks
where the difference between 'unsigned int' and __poll_t will matter.
See Documentation/dev-tools/sparse.rst for more info about it.

Best regards,
-- Luc Van Oostenryck