openbmc.lists.ozlabs.org archive mirror
 help / color / mirror / Atom feed
From: "Winiarska, Iwona" <iwona.winiarska@intel.com>
To: "Williams, Dan J" <dan.j.williams@intel.com>
Cc: "linux-aspeed@lists.ozlabs.org" <linux-aspeed@lists.ozlabs.org>,
	"linux-doc@vger.kernel.org" <linux-doc@vger.kernel.org>,
	"zweiss@equinix.com" <zweiss@equinix.com>,
	"jae.hyun.yoo@linux.intel.com" <jae.hyun.yoo@linux.intel.com>,
	"andriy.shevchenko@linux.intel.com"
	<andriy.shevchenko@linux.intel.com>,
	"corbet@lwn.net" <corbet@lwn.net>,
	"openbmc@lists.ozlabs.org" <openbmc@lists.ozlabs.org>,
	"x86@kernel.org" <x86@kernel.org>,
	"pierre-louis.bossart@linux.intel.com"
	<pierre-louis.bossart@linux.intel.com>,
	"mingo@redhat.com" <mingo@redhat.com>,
	"linux@roeck-us.net" <linux@roeck-us.net>,
	"devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
	"jdelvare@suse.com" <jdelvare@suse.com>,
	"arnd@arndb.de" <arnd@arndb.de>,
	"robh+dt@kernel.org" <robh+dt@kernel.org>,
	"bp@alien8.de" <bp@alien8.de>,
	"Lutomirski, Andy" <luto@kernel.org>,
	"tglx@linutronix.de" <tglx@linutronix.de>,
	"mchehab@kernel.org" <mchehab@kernel.org>,
	"linux-arm-kernel@lists.infradead.org"
	<linux-arm-kernel@lists.infradead.org>,
	"linux-hwmon@vger.kernel.org" <linux-hwmon@vger.kernel.org>,
	"Luck, Tony" <tony.luck@intel.com>,
	"andrew@aj.id.au" <andrew@aj.id.au>,
	"gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>,
	"rdunlap@infradead.org" <rdunlap@infradead.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"yazen.ghannam@amd.com" <yazen.ghannam@amd.com>,
	"olof@lixom.net" <olof@lixom.net>
Subject: Re: [PATCH v2 09/15] peci: Add sysfs interface for PECI bus
Date: Mon, 15 Nov 2021 22:19:04 +0000	[thread overview]
Message-ID: <0fb36e270cd497ade90eb0a4e9882819af3472dd.camel@intel.com> (raw)
In-Reply-To: <CAPcyv4hhtTi+dKspjoamYj53GxT4Ot_1pG5-eavUJdihD8iAEg@mail.gmail.com>

On Fri, 2021-08-27 at 12:11 -0700, Dan Williams wrote:
> On Tue, Aug 3, 2021 at 4:35 AM Iwona Winiarska
> <iwona.winiarska@intel.com> wrote:
> > 
> > PECI devices may not be discoverable at the time when PECI controller is
> > being added (e.g. BMC can boot up when the Host system is still in S5).
> > Since we currently don't have the capabilities to figure out the Host
> > system state inside the PECI subsystem itself, we have to rely on
> > userspace to do it for us.
> > 
> > In the future, PECI subsystem may be expanded with mechanisms that allow
> > us to avoid depending on userspace interaction (e.g. CPU presence could
> > be detected using GPIO, and the information on whether it's discoverable
> > could be obtained over IPMI).
> 
> Thanks for this detail.
> 
> > Unfortunately, those methods may ultimately not be available (support
> > will vary from platform to platform), which means that we still need
> > platform independent method triggered by userspace.
> > 
> > Signed-off-by: Iwona Winiarska <iwona.winiarska@intel.com>
> > ---
> >  Documentation/ABI/testing/sysfs-bus-peci | 16 +++++
> >  drivers/peci/Makefile                    |  2 +-
> >  drivers/peci/core.c                      |  3 +-
> >  drivers/peci/device.c                    |  1 +
> >  drivers/peci/internal.h                  |  5 ++
> >  drivers/peci/sysfs.c                     | 82 ++++++++++++++++++++++++
> >  6 files changed, 107 insertions(+), 2 deletions(-)
> >  create mode 100644 Documentation/ABI/testing/sysfs-bus-peci
> >  create mode 100644 drivers/peci/sysfs.c
> > 
> > diff --git a/Documentation/ABI/testing/sysfs-bus-peci
> > b/Documentation/ABI/testing/sysfs-bus-peci
> > new file mode 100644
> > index 000000000000..56c2b2216bbd
> > --- /dev/null
> > +++ b/Documentation/ABI/testing/sysfs-bus-peci
> > @@ -0,0 +1,16 @@
> > +What:          /sys/bus/peci/rescan
> > +Date:          July 2021
> > +KernelVersion: 5.15
> > +Contact:       Iwona Winiarska <iwona.winiarska@intel.com>
> > +Description:
> > +               Writing a non-zero value to this attribute will
> > +               initiate scan for PECI devices on all PECI controllers
> > +               in the system.
> > +
> > +What:          /sys/bus/peci/devices/<controller_id>-<device_addr>/remove
> > +Date:          July 2021
> > +KernelVersion: 5.15
> > +Contact:       Iwona Winiarska <iwona.winiarska@intel.com>
> > +Description:
> > +               Writing a non-zero value to this attribute will
> > +               remove the PECI device and any of its children.
> > diff --git a/drivers/peci/Makefile b/drivers/peci/Makefile
> > index c5f9d3fe21bb..917f689e147a 100644
> > --- a/drivers/peci/Makefile
> > +++ b/drivers/peci/Makefile
> > @@ -1,7 +1,7 @@
> >  # SPDX-License-Identifier: GPL-2.0-only
> > 
> >  # Core functionality
> > -peci-y := core.o request.o device.o
> > +peci-y := core.o request.o device.o sysfs.o
> >  obj-$(CONFIG_PECI) += peci.o
> > 
> >  # Hardware specific bus drivers
> > diff --git a/drivers/peci/core.c b/drivers/peci/core.c
> > index d143f1a7fe98..c473acb3c2a0 100644
> > --- a/drivers/peci/core.c
> > +++ b/drivers/peci/core.c
> > @@ -34,7 +34,7 @@ struct device_type peci_controller_type = {
> >         .release        = peci_controller_dev_release,
> >  };
> > 
> > -static int peci_controller_scan_devices(struct peci_controller *controller)
> > +int peci_controller_scan_devices(struct peci_controller *controller)
> >  {
> >         int ret;
> >         u8 addr;
> > @@ -159,6 +159,7 @@ EXPORT_SYMBOL_NS_GPL(devm_peci_controller_add, PECI);
> > 
> >  struct bus_type peci_bus_type = {
> >         .name           = "peci",
> > +       .bus_groups     = peci_bus_groups,
> >  };
> > 
> >  static int __init peci_init(void)
> > diff --git a/drivers/peci/device.c b/drivers/peci/device.c
> > index 32811248997b..d77d9dabd51e 100644
> > --- a/drivers/peci/device.c
> > +++ b/drivers/peci/device.c
> > @@ -110,5 +110,6 @@ static void peci_device_release(struct device *dev)
> >  }
> > 
> >  struct device_type peci_device_type = {
> > +       .groups         = peci_device_groups,
> >         .release        = peci_device_release,
> >  };
> > diff --git a/drivers/peci/internal.h b/drivers/peci/internal.h
> > index 57d11a902c5d..978e12c8e1d3 100644
> > --- a/drivers/peci/internal.h
> > +++ b/drivers/peci/internal.h
> > @@ -8,6 +8,7 @@
> >  #include <linux/types.h>
> > 
> >  struct peci_controller;
> > +struct attribute_group;
> >  struct peci_device;
> >  struct peci_request;
> > 
> > @@ -19,12 +20,16 @@ struct peci_request *peci_request_alloc(struct
> > peci_device *device, u8 tx_len, u
> >  void peci_request_free(struct peci_request *req);
> > 
> >  extern struct device_type peci_device_type;
> > +extern const struct attribute_group *peci_device_groups[];
> > 
> >  int peci_device_create(struct peci_controller *controller, u8 addr);
> >  void peci_device_destroy(struct peci_device *device);
> > 
> >  extern struct bus_type peci_bus_type;
> > +extern const struct attribute_group *peci_bus_groups[];
> 
> To me, sysfs.c is small enough to just fold into core.c, then no need
> to declare public attribute arrays like this, but up to you if you
> prefer the sysfs.c split.

Left the sysfs split for now.

> 
> > 
> >  extern struct device_type peci_controller_type;
> > 
> > +int peci_controller_scan_devices(struct peci_controller *controller);
> > +
> >  #endif /* __PECI_INTERNAL_H */
> > diff --git a/drivers/peci/sysfs.c b/drivers/peci/sysfs.c
> > new file mode 100644
> > index 000000000000..db9ef05776e3
> > --- /dev/null
> > +++ b/drivers/peci/sysfs.c
> > @@ -0,0 +1,82 @@
> > +// SPDX-License-Identifier: GPL-2.0-only
> > +// Copyright (c) 2021 Intel Corporation
> > +
> > +#include <linux/device.h>
> > +#include <linux/kernel.h>
> > +#include <linux/peci.h>
> > +
> > +#include "internal.h"
> > +
> > +static int rescan_controller(struct device *dev, void *data)
> > +{
> > +       if (dev->type != &peci_controller_type)
> > +               return 0;
> > +
> > +       return peci_controller_scan_devices(to_peci_controller(dev));
> > +}
> > +
> > +static ssize_t rescan_store(struct bus_type *bus, const char *buf, size_t
> > count)
> > +{
> > +       bool res;
> > +       int ret;
> > +
> > +       ret = kstrtobool(buf, &res);
> > +       if (ret)
> > +               return ret;
> > +
> > +       if (!res)
> > +               return count;
> > +
> > +       ret = bus_for_each_dev(&peci_bus_type, NULL, NULL,
> > rescan_controller);
> > +       if (ret)
> > +               return ret;
> > +
> > +       return count;
> > +}
> > +static BUS_ATTR_WO(rescan);
> > +
> > +static struct attribute *peci_bus_attrs[] = {
> > +       &bus_attr_rescan.attr,
> > +       NULL
> > +};
> > +
> > +static const struct attribute_group peci_bus_group = {
> > +       .attrs = peci_bus_attrs,
> > +};
> > +
> > +const struct attribute_group *peci_bus_groups[] = {
> > +       &peci_bus_group,
> > +       NULL
> > +};
> > +
> > +static ssize_t remove_store(struct device *dev, struct device_attribute
> > *attr,
> > +                           const char *buf, size_t count)
> > +{
> > +       struct peci_device *device = to_peci_device(dev);
> > +       bool res;
> > +       int ret;
> > +
> > +       ret = kstrtobool(buf, &res);
> > +       if (ret)
> > +               return ret;
> > +
> > +       if (res && device_remove_file_self(dev, attr))
> > +               peci_device_destroy(device);
> 
> How do you solve races between sysfs device remove and controller
> device remove? Looks like double-free at first glance. Have a look at
> the  kill_device() helper as one way to resolve this double-delete
> race..

Done.

Thanks
-Iwona

> 
> > +
> > +       return count;
> > +}
> > +static DEVICE_ATTR_IGNORE_LOCKDEP(remove, 0200, NULL, remove_store);
> > +
> > +static struct attribute *peci_device_attrs[] = {
> > +       &dev_attr_remove.attr,
> > +       NULL
> > +};
> > +
> > +static const struct attribute_group peci_device_group = {
> > +       .attrs = peci_device_attrs,
> > +};
> > +
> > +const struct attribute_group *peci_device_groups[] = {
> > +       &peci_device_group,
> > +       NULL
> > +};
> > --
> > 2.31.1
> > 

  reply	other threads:[~2021-11-16  1:59 UTC|newest]

Thread overview: 49+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-03 11:31 [PATCH v2 00/15] Introduce PECI subsystem Iwona Winiarska
2021-08-03 11:31 ` [PATCH v2 01/15] x86/cpu: Move intel-family to arch-independent headers Iwona Winiarska
2021-10-04 19:03   ` Borislav Petkov
2021-10-11 19:21     ` Winiarska, Iwona
2021-10-11 19:40       ` Dave Hansen
2021-10-11 20:53         ` Winiarska, Iwona
2021-10-11 23:12           ` Dave Hansen
2021-10-11 20:06       ` Borislav Petkov
2021-10-11 20:38         ` Winiarska, Iwona
2021-10-11 21:31           ` Borislav Petkov
2021-10-12 23:15             ` Winiarska, Iwona
2021-10-13  6:42               ` Borislav Petkov
2021-08-03 11:31 ` [PATCH v2 02/15] x86/cpu: Extract cpuid helpers to arch-independent Iwona Winiarska
2021-10-04 19:08   ` Borislav Petkov
2021-10-11 19:32     ` Winiarska, Iwona
2021-08-03 11:31 ` [PATCH v2 03/15] dt-bindings: Add generic bindings for PECI Iwona Winiarska
2021-08-11 18:11   ` Rob Herring
2021-08-03 11:31 ` [PATCH v2 04/15] dt-bindings: Add bindings for peci-aspeed Iwona Winiarska
2021-08-11 18:11   ` Rob Herring
2021-08-03 11:31 ` [PATCH v2 05/15] ARM: dts: aspeed: Add PECI controller nodes Iwona Winiarska
2021-08-03 11:31 ` [PATCH v2 06/15] peci: Add core infrastructure Iwona Winiarska
2021-08-25 22:58   ` Dan Williams
2021-08-26 22:40     ` Winiarska, Iwona
2021-08-03 11:31 ` [PATCH v2 07/15] peci: Add peci-aspeed controller driver Iwona Winiarska
2021-08-26  1:35   ` Dan Williams
2021-08-26 23:54     ` Winiarska, Iwona
2021-08-27 16:24       ` Dan Williams
2021-08-29 19:42         ` Winiarska, Iwona
2021-08-03 11:31 ` [PATCH v2 08/15] peci: Add device detection Iwona Winiarska
2021-08-27 19:01   ` Dan Williams
2021-11-15 22:18     ` Winiarska, Iwona
2021-08-03 11:31 ` [PATCH v2 09/15] peci: Add sysfs interface for PECI bus Iwona Winiarska
2021-08-27 19:11   ` Dan Williams
2021-11-15 22:19     ` Winiarska, Iwona [this message]
2021-08-03 11:31 ` [PATCH v2 10/15] peci: Add support for PECI device drivers Iwona Winiarska
2021-08-27 21:19   ` Dan Williams
2021-11-15 22:20     ` Winiarska, Iwona
2021-08-03 11:31 ` [PATCH v2 11/15] peci: Add peci-cpu driver Iwona Winiarska
2021-08-03 11:31 ` [PATCH v2 12/15] hwmon: peci: Add cputemp driver Iwona Winiarska
2021-08-03 15:24   ` Guenter Roeck
2021-08-04 10:43     ` Winiarska, Iwona
2021-08-03 11:31 ` [PATCH v2 13/15] hwmon: peci: Add dimmtemp driver Iwona Winiarska
2021-08-03 15:39   ` Guenter Roeck
2021-08-04 10:46     ` Winiarska, Iwona
2021-08-04 17:33       ` Guenter Roeck
2021-08-05 21:48         ` Winiarska, Iwona
2021-08-03 11:31 ` [PATCH v2 14/15] docs: hwmon: Document PECI drivers Iwona Winiarska
2021-08-03 11:31 ` [PATCH v2 15/15] docs: Add PECI documentation Iwona Winiarska
2021-08-05 12:17 ` [PATCH v2 00/15] Introduce PECI subsystem Greg Kroah-Hartman

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=0fb36e270cd497ade90eb0a4e9882819af3472dd.camel@intel.com \
    --to=iwona.winiarska@intel.com \
    --cc=andrew@aj.id.au \
    --cc=andriy.shevchenko@linux.intel.com \
    --cc=arnd@arndb.de \
    --cc=bp@alien8.de \
    --cc=corbet@lwn.net \
    --cc=dan.j.williams@intel.com \
    --cc=devicetree@vger.kernel.org \
    --cc=gregkh@linuxfoundation.org \
    --cc=jae.hyun.yoo@linux.intel.com \
    --cc=jdelvare@suse.com \
    --cc=linux-arm-kernel@lists.infradead.org \
    --cc=linux-aspeed@lists.ozlabs.org \
    --cc=linux-doc@vger.kernel.org \
    --cc=linux-hwmon@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux@roeck-us.net \
    --cc=luto@kernel.org \
    --cc=mchehab@kernel.org \
    --cc=mingo@redhat.com \
    --cc=olof@lixom.net \
    --cc=openbmc@lists.ozlabs.org \
    --cc=pierre-louis.bossart@linux.intel.com \
    --cc=rdunlap@infradead.org \
    --cc=robh+dt@kernel.org \
    --cc=tglx@linutronix.de \
    --cc=tony.luck@intel.com \
    --cc=x86@kernel.org \
    --cc=yazen.ghannam@amd.com \
    --cc=zweiss@equinix.com \
    --subject='Re: [PATCH v2 09/15] peci: Add sysfs interface for PECI bus' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).