From: Dragan Cvetic <draganc@xilinx.com>
To: Arnd Bergmann <arnd@arndb.de>
Cc: gregkh <gregkh@linuxfoundation.org>,
Michal Simek <michals@xilinx.com>,
Derek Kiernan <dkiernan@xilinx.com>,
Linux ARM <linux-arm-kernel@lists.infradead.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: RE: [PATCH 04/12] misc: xilinx_sdfec: Add open, close and ioctl
Date: Tue, 19 Mar 2019 18:10:35 +0000 [thread overview]
Message-ID: <BL0PR02MB5681C0D1D5DB5F57E3640D9ACB400@BL0PR02MB5681.namprd02.prod.outlook.com> (raw)
In-Reply-To: <CAK8P3a115AM-iuGPgqEYfR7p9HMQL3fm9eL7370ogf3-DBrjbA@mail.gmail.com>
> -----Original Message-----
> From: Arnd Bergmann [mailto:arnd@arndb.de]
> Sent: Tuesday 19 March 2019 15:36
> To: Dragan Cvetic <draganc@xilinx.com>
> Cc: gregkh <gregkh@linuxfoundation.org>; Michal Simek <michals@xilinx.com>; Linux ARM <linux-arm-kernel@lists.infradead.org>;
> Derek Kiernan <dkiernan@xilinx.com>; Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
> Subject: Re: [PATCH 04/12] misc: xilinx_sdfec: Add open, close and ioctl
>
> On Tue, Mar 19, 2019 at 3:59 PM Dragan Cvetic <draganc@xilinx.com> wrote:
> > >
> > > > + /* Only one open per device at a time */
> > > > + if (!atomic_dec_and_test(&xsdfec->open_count)) {
> > > > + atomic_inc(&xsdfec->open_count);
> > > > + return -EBUSY;
> > > > + }
> > >
> > > What is that limitation for? Is it worse to open it twice than
> > > to dup() or fork()?
> > >
> > The device can be opened only once.
>
> What I mean here is that preventing the double open() is
> a fairly weak protection: it means you cannot have multiple
> 'struct file' pointers attached to the same inode, but you
> can still have the same 'struct file' being available to
> multiple processes.
>
Could you please suggest the solution?
My intention was to prevent more than one process access the same device.
> Arnd
Thanks
Dragan
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next prev parent reply other threads:[~2019-03-19 18:10 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-19 12:04 [PATCH 00/12] misc: xilinx sd-fec driver Dragan Cvetic
2019-03-19 12:04 ` [PATCH 01/12] dt-bindings: xilinx-sdfec: Add SDFEC binding Dragan Cvetic
2019-03-19 12:04 ` [PATCH 02/12] misc: xilinx-sdfec: add core driver Dragan Cvetic
2019-03-19 12:04 ` [PATCH 03/12] misc: xilinx_sdfec: Add CCF support Dragan Cvetic
2019-03-19 12:04 ` [PATCH 04/12] misc: xilinx_sdfec: Add open, close and ioctl Dragan Cvetic
2019-03-19 13:17 ` Arnd Bergmann
2019-03-19 14:59 ` Dragan Cvetic
2019-03-19 15:36 ` Arnd Bergmann
2019-03-19 18:10 ` Dragan Cvetic [this message]
2019-03-19 19:46 ` Arnd Bergmann
2019-04-09 8:35 ` Dragan Cvetic
2019-03-19 12:04 ` [PATCH 05/12] misc: xilinx_sdfec: Store driver config and state Dragan Cvetic
2019-03-19 12:04 ` [PATCH 06/12] misc: xilinx_sdfec: Add ability to configure turbo mode Dragan Cvetic
2019-03-19 12:04 ` [PATCH 07/12] misc: xilinx_sdfec: Add ability to configure LDPC Dragan Cvetic
2019-03-19 12:04 ` [PATCH 08/12] misc: xilinx_sdfec: Add ability to get/set config Dragan Cvetic
2019-03-19 13:05 ` Arnd Bergmann
2019-03-19 14:02 ` Dragan Cvetic
2019-03-19 12:04 ` [PATCH 09/12] misc: xilinx_sdfec: Support poll file operation Dragan Cvetic
2019-03-19 12:04 ` [PATCH 10/12] misc: xilinx_sdfec: Add stats & status ioctls Dragan Cvetic
2019-03-19 12:04 ` [PATCH 11/12] Docs: misc: xilinx_sdfec: Add documentation Dragan Cvetic
2019-03-19 12:04 ` [PATCH 12/12] MAINTAINERS: add maintainer for SD-FEC support Dragan Cvetic
2019-03-19 12:17 ` [PATCH 00/12] misc: xilinx sd-fec driver Michal Simek
2019-03-19 13:44 ` Dragan Cvetic
2019-03-19 13:51 ` Michal Simek
2019-03-19 13:55 ` Dragan Cvetic
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