On Sun, Jun 09, 2019 at 06:48:31PM +0000, Dragan Cvetic wrote: > > > > -----Original Message----- > > From: Greg KH [mailto:gre...@linuxfoundation.org] > > Sent: Sunday 9 June 2019 12:23 > > To: Dragan Cvetic <drag...@xilinx.com> > > Cc: a...@arndb.de; Michal Simek <mich...@xilinx.com>; > > linux-arm-ker...@lists.infradead.org; robh...@kernel.org; > > mark.rutl...@arm.com; devicet...@vger.kernel.org; > > linux-kernel@vger.kernel.org; Derek Kiernan <dkier...@xilinx.com> > > Subject: Re: [PATCH V5 02/11] misc: xilinx-sdfec: add core driver > > > > On Sun, Jun 09, 2019 at 01:04:07AM +0100, Dragan Cvetic wrote: > > > Implement a platform driver that matches with xlnx, > > > sd-fec-1.1 device tree node and registers as a character > > > device, including: > > > - SD-FEC driver binds to sdfec DT node. > > > - creates and initialise an initial driver dev structure. > > > - add the driver in Linux build and Kconfig. > > > > > > Tested-by: Dragan Cvetic <dragan.cve...@xilinx.com> > > > Signed-off-by: Derek Kiernan <derek.kier...@xilinx.com> > > > Signed-off-by: Dragan Cvetic <dragan.cve...@xilinx.com> > > > --- > > > drivers/misc/Kconfig | 12 +++++ > > > drivers/misc/Makefile | 1 + > > > drivers/misc/xilinx_sdfec.c | 118 > > > ++++++++++++++++++++++++++++++++++++++++++++ > > > 3 files changed, 131 insertions(+) > > > create mode 100644 drivers/misc/xilinx_sdfec.c > > > > > > diff --git a/drivers/misc/Kconfig b/drivers/misc/Kconfig > > > index 6b0417b..319a6bf 100644 > > > --- a/drivers/misc/Kconfig > > > +++ b/drivers/misc/Kconfig > > > @@ -471,6 +471,18 @@ config PCI_ENDPOINT_TEST > > > Enable this configuration option to enable the host side test > > > driver > > > for PCI Endpoint. > > > > > > +config XILINX_SDFEC > > > + tristate "Xilinx SDFEC 16" > > > + help > > > + This option enables support for the Xilinx SDFEC (Soft Decision > > > + Forward Error Correction) driver. This enables a char driver > > > + for the SDFEC. > > > + > > > + You may select this driver if your design instantiates the > > > + SDFEC(16nm) hardened block. To compile this as a module choose M. > > > + > > > + If unsure, say N. > > > + > > > config MISC_RTSX > > > tristate > > > default MISC_RTSX_PCI || MISC_RTSX_USB > > > diff --git a/drivers/misc/Makefile b/drivers/misc/Makefile > > > index b9affcd..0cb3546 100644 > > > --- a/drivers/misc/Makefile > > > +++ b/drivers/misc/Makefile > > > @@ -59,3 +59,4 @@ obj-$(CONFIG_OCXL) += ocxl/ > > > obj-y += cardreader/ > > > obj-$(CONFIG_PVPANIC) += pvpanic.o > > > obj-$(CONFIG_HABANA_AI) += habanalabs/ > > > +obj-$(CONFIG_XILINX_SDFEC) += xilinx_sdfec.o > > > diff --git a/drivers/misc/xilinx_sdfec.c b/drivers/misc/xilinx_sdfec.c > > > new file mode 100644 > > > index 0000000..75cc980 > > > --- /dev/null > > > +++ b/drivers/misc/xilinx_sdfec.c > > > @@ -0,0 +1,118 @@ > > > +// SPDX-License-Identifier: GPL-2.0 > > > +/* > > > + * Xilinx SDFEC > > > + * > > > + * Copyright (C) 2019 Xilinx, Inc. > > > + * > > > + * Description: > > > + * This driver is developed for SDFEC16 (Soft Decision FEC 16nm) > > > + * IP. It exposes a char device which supports file operations > > > + * like open(), close() and ioctl(). > > > + */ > > > + > > > +#include <linux/miscdevice.h> > > > +#include <linux/io.h> > > > +#include <linux/interrupt.h> > > > +#include <linux/kernel.h> > > > +#include <linux/module.h> > > > +#include <linux/of_platform.h> > > > +#include <linux/poll.h> > > > +#include <linux/slab.h> > > > +#include <linux/clk.h> > > > + > > > +static int xsdfec_ndevs; > > > > You should use an idr for this, not just a number you bump up and down. > > This will not work properly at all. > > > > Think about this situation: > > probe device 0 > > xsdfec_ndevs = 1 > > probe device 1 > > xsdfec_ndevs = 2 > > remove device 0 > > xsdfec_ndevs = 0 > > probe another device > > misc device fails due to duplicate name. > > > > My bad. > I can use idr, but couldn't be better optimized code if use simple mutex to > protect the variable.
mutex does not protect from this at all, it's a logic bug. Think about adding 5 devices and then removing the 2nd one. What is the number assigned to the new device that is added afterward? And you need a mutex for the idr anyway, if you are touching it in a non probe/release callback way (those are already serialized by the bus lock). thanks, greg k-h
