From: Amey Narkhede <ameynarkhede03@gmail.com>
To: Bjorn Helgaas <helgaas@kernel.org>
Cc: alex.williamson@redhat.com,
Raphael Norwitz <raphael.norwitz@nutanix.com>,
linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org,
kw@linux.com, Shanker Donthineni <sdonthineni@nvidia.com>,
Sinan Kaya <okaya@kernel.org>, Len Brown <lenb@kernel.org>,
"Rafael J. Wysocki" <rjw@rjwysocki.net>
Subject: Re: [PATCH v10 4/8] PCI/sysfs: Allow userspace to query and set device reset mechanism
Date: Thu, 29 Jul 2021 00:28:31 +0530 [thread overview]
Message-ID: <20210728185831.isdqa5t5oxxjfhnv@archlinux> (raw)
In-Reply-To: <20210728181333.GA836307@bjorn-Precision-5520>
On 21/07/28 01:13PM, Bjorn Helgaas wrote:
> On Wed, Jul 28, 2021 at 11:29:50PM +0530, Amey Narkhede wrote:
> > On 21/07/27 06:28PM, Bjorn Helgaas wrote:
> > > On Fri, Jul 09, 2021 at 06:08:09PM +0530, Amey Narkhede wrote:
> > > > Add reset_method sysfs attribute to enable user to query and set user
> > > > preferred device reset methods and their ordering.
> > > >
> > > > Co-developed-by: Alex Williamson <alex.williamson@redhat.com>
> > > > Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
> > > > Signed-off-by: Amey Narkhede <ameynarkhede03@gmail.com>
> > > > ---
> > > > Documentation/ABI/testing/sysfs-bus-pci | 19 +++++
> > > > drivers/pci/pci-sysfs.c | 103 ++++++++++++++++++++++++
> > > > 2 files changed, 122 insertions(+)
> > > >
> > > > diff --git a/Documentation/ABI/testing/sysfs-bus-pci b/Documentation/ABI/testing/sysfs-bus-pci
> > > > index ef00fada2..43f4e33c7 100644
> > > > --- a/Documentation/ABI/testing/sysfs-bus-pci
> > > > +++ b/Documentation/ABI/testing/sysfs-bus-pci
> > > > @@ -121,6 +121,25 @@ Description:
> > > > child buses, and re-discover devices removed earlier
> > > > from this part of the device tree.
> > > >
> > > > +What: /sys/bus/pci/devices/.../reset_method
> > > > +Date: March 2021
> > > > +Contact: Amey Narkhede <ameynarkhede03@gmail.com>
> > > > +Description:
> > > > + Some devices allow an individual function to be reset
> > > > + without affecting other functions in the same slot.
> > > > +
> > > > + For devices that have this support, a file named
> > > > + reset_method will be present in sysfs. Initially reading
> > > > + this file will give names of the device supported reset
> > > > + methods and their ordering. After write, this file will
> > > > + give names and ordering of currently enabled reset methods.
> > > > + Writing the name or comma separated list of names of any of
> > > > + the device supported reset methods to this file will set
> > > > + the reset methods and their ordering to be used when
> > > > + resetting the device. Writing empty string to this file
> > > > + will disable ability to reset the device and writing
> > > > + "default" will return to the original value.
> > > > +
> > > > What: /sys/bus/pci/devices/.../reset
> > > > Date: July 2009
> > > > Contact: Michael S. Tsirkin <mst@redhat.com>
> > >
> > [...]
> >
> > > > + int i;
> > > > +
> > > > + if (sysfs_streq(name, ""))
> > > > + continue;
> > > > +
> > > > + name = strim(name);
> > > > +
> > > > + for (i = 1; i < PCI_NUM_RESET_METHODS; i++) {
> > > > + if (sysfs_streq(name, pci_reset_fn_methods[i].name) &&
> > > > + !pci_reset_fn_methods[i].reset_fn(pdev, 1)) {
> > > > + reset_methods[n++] = i;
> > >
> > > Can we build this directly in pdev->reset_methods[] so we don't need
> > > the memcpy() below?
> > >
> > This is to avoid writing partial values directly to dev->reset_methods.
> > So for example if user writes flr,unsupported_value then
> > dev->reset_methods should not be modified even though flr is valid reset
> > method in this example to avoid partial writes. Either operation(in this
> > case writing supported reset methods to reset_method attr) succeeds
> > completely or it fails othewise.
>
> I guess the question is, if somebody writes
>
> flr junk bus
>
> and we set the supported methods to "flr bus", is that OK? It seems
> OK to me; obviously we have to protect ourselves from attack, but
> over-zealous checking can make things unnecessarily complicated.
The problem is once we encounter "junk" we return -EINVAL so in your
example we only set flr.
Thanks,
Amey
next prev parent reply other threads:[~2021-07-28 18:58 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-09 12:38 [PATCH v10 0/8] Expose and manage PCI device reset Amey Narkhede
2021-07-09 12:38 ` [PATCH v10 1/8] PCI: Add pcie_reset_flr to follow calling convention of other reset methods Amey Narkhede
2021-07-12 22:07 ` Alex Williamson
2021-07-27 22:12 ` Bjorn Helgaas
2021-07-28 18:54 ` Shanker R Donthineni
2021-07-28 20:23 ` Bjorn Helgaas
2021-07-28 21:58 ` Shanker R Donthineni
2021-07-28 22:04 ` Shanker R Donthineni
2021-07-28 22:16 ` Bjorn Helgaas
2021-07-09 12:38 ` [PATCH v10 2/8] PCI: Add new array for keeping track of ordering of " Amey Narkhede
2021-07-27 22:59 ` Bjorn Helgaas
2021-07-28 17:45 ` Amey Narkhede
2021-07-28 17:59 ` Bjorn Helgaas
2021-07-28 18:17 ` Shanker R Donthineni
2021-07-28 18:08 ` Shanker R Donthineni
2021-07-28 18:31 ` Shanker R Donthineni
2021-07-28 20:25 ` Bjorn Helgaas
2021-07-28 22:01 ` Shanker R Donthineni
2021-07-09 12:38 ` [PATCH v10 3/8] PCI: Remove reset_fn field from pci_dev Amey Narkhede
2021-07-09 12:38 ` [PATCH v10 4/8] PCI/sysfs: Allow userspace to query and set device reset mechanism Amey Narkhede
2021-07-27 23:28 ` Bjorn Helgaas
2021-07-28 1:27 ` Krzysztof Wilczyński
2021-07-28 15:36 ` Bjorn Helgaas
2021-07-28 17:59 ` Amey Narkhede
2021-07-28 18:13 ` Bjorn Helgaas
2021-07-28 18:58 ` Amey Narkhede [this message]
2021-07-28 20:18 ` Bjorn Helgaas
2021-07-31 19:15 ` Amey Narkhede
2021-07-28 17:09 ` Bjorn Helgaas
2021-07-09 12:38 ` [PATCH v10 5/8] PCI: Define a function to set ACPI_COMPANION in pci_dev Amey Narkhede
2021-07-12 22:29 ` Alex Williamson
2021-07-09 12:38 ` [PATCH v10 6/8] PCI: Setup ACPI fwnode early and at the same time with OF Amey Narkhede
2021-07-12 23:09 ` Alex Williamson
2021-07-27 23:30 ` Bjorn Helgaas
2021-07-27 23:50 ` Shanker R Donthineni
2021-07-09 12:38 ` [PATCH v10 7/8] PCI: Add support for ACPI _RST reset method Amey Narkhede
2021-07-12 23:09 ` Alex Williamson
2021-07-13 0:51 ` Shanker R Donthineni
2021-07-14 22:56 ` Alex Williamson
2021-07-09 12:38 ` [PATCH v10 8/8] PCI: Change the type of probe argument in reset functions Amey Narkhede
2021-07-12 22:24 ` Alex Williamson
2021-07-27 22:22 ` Bjorn Helgaas
2021-07-28 17:35 ` Amey Narkhede
2021-07-28 17:55 ` Bjorn Helgaas
2021-07-09 12:46 ` [PATCH v10 0/8] Expose and manage PCI device reset Amey Narkhede
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