linux-pci.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Shanker R Donthineni <sdonthineni@nvidia.com>
To: "Krzysztof Wilczyński" <kw@linux.com>,
	"Amey Narkhede" <ameynarkhede03@gmail.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>, <alex.williamson@redhat.com>,
	Raphael Norwitz <raphael.norwitz@nutanix.com>,
	<linux-pci@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
	Sinan Kaya <okaya@kernel.org>
Subject: Re: [PATCH v5 4/7] PCI/sysfs: Allow userspace to query and set device reset mechanism
Date: Sun, 6 Jun 2021 09:27:56 -0500	[thread overview]
Message-ID: <87aaf482-dbfe-adaa-eea0-1c6febe6503c@nvidia.com> (raw)
In-Reply-To: <20210606125800.GA76573@rocinante.localdomain>

Hi Krzysztof,

On 6/6/21 7:58 AM, Krzysztof Wilczyński wrote:
> External email: Use caution opening links or attachments
>
>
> Hi Amey and Shanker,
>
> [...]
>> +static ssize_t reset_method_show(struct device *dev,
>> +                              struct device_attribute *attr,
>> +                              char *buf)
>> +{
>> +     struct pci_dev *pdev = to_pci_dev(dev);
>> +     ssize_t len = 0;
>> +     int i, prio;
>> +
>> +     for (prio = PCI_RESET_METHODS_NUM; prio; prio--) {
>> +             for (i = 0; i < PCI_RESET_METHODS_NUM; i++) {
>> +                     if (prio == pdev->reset_methods[i]) {
>> +                             len += sysfs_emit_at(buf, len, "%s%s",
>> +                                                  len ? "," : "",
>> +                                                  pci_reset_fn_methods[i].name);
>> +                             break;
>> +                     }
>> +             }
>> +
>> +             if (i == PCI_RESET_METHODS_NUM)
>> +                     break;
>> +     }
>> +
>> +     return len;
>> +}
> Make sure to include trailing newline when exposing values through the
> sysfs object to the userspace in the above show() function.

Agree new line is needed. Will fix it.
> [...]
>> +static ssize_t reset_method_store(struct device *dev,
>> +                               struct device_attribute *attr,
>> +                               const char *buf, size_t count)
> [...]
>> +
>> +     while ((name = strsep((char **)&buf, ",")) != NULL) {
> [...]
>
> This is something that I wonder could benefit from the following:
>
>   char *options, *end;
>
>   if (count >= (PAGE_SIZE - 1))
>         return -EINVAL;
>
>   options = kstrndup(buf, count, GFP_KERNEL);
>   if (!options)
>         return -ENOMEM;
>
>   while ((name = strsep(&options, ",")) != NULL) {
>         ...
>   }
>
>   ...
>
>   kfree(options);
>
> Why?  To avoid changing the string buffer that has been passed to
> reset_method_store() as strsep() while parsing will update the content
> of the buffer.  The cast to (char **), aside of most definitely allowing
> to suppress the probable compiler warning, will also allow for what
> should be a technically a constant string (to which we got a pointer to)
> to be modified.  I am not sure how much could this be of a problem, but
> I would try not to do it, if possible.

Thanks, will use temporary buffer for parsing string.
>
> [...]
>> +set_reset_methods:
>> +     memcpy(pdev->reset_methods, reset_methods, sizeof(reset_methods));
>> +     return count;
>> +}
>> +
>> +static DEVICE_ATTR_RW(reset_method);
> A small nitpikc: customary there is no space (a newline) between the
> function and the macro, the macro follows immediately after.

Will fix it.
>         Krzysztof


  reply	other threads:[~2021-06-06 14:28 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-29 19:25 [PATCH v5 0/7] Expose and manage PCI device reset Amey Narkhede
2021-05-29 19:25 ` [PATCH v5 1/7] PCI: Add pcie_reset_flr to follow calling convention of other reset methods Amey Narkhede
2021-05-29 19:25 ` [PATCH v5 2/7] PCI: Add new array for keeping track of ordering of " Amey Narkhede
2021-06-02 21:37   ` Shanker R Donthineni
2021-06-05 20:55   ` Bjorn Helgaas
2021-05-29 19:25 ` [PATCH v5 3/7] PCI: Remove reset_fn field from pci_dev Amey Narkhede
2021-06-02 22:16   ` Shanker R Donthineni
2021-06-05 20:57   ` Bjorn Helgaas
2021-05-29 19:25 ` [PATCH v5 4/7] PCI/sysfs: Allow userspace to query and set device reset mechanism Amey Narkhede
2021-06-02 22:17   ` Shanker R Donthineni
2021-06-06 12:58   ` Krzysztof Wilczyński
2021-06-06 14:27     ` Shanker R Donthineni [this message]
2021-05-29 19:25 ` [PATCH v5 5/7] PCI: Add support for a function level reset based on _RST method Amey Narkhede
2021-06-05 20:53   ` Bjorn Helgaas
2021-06-06  0:04     ` Shanker R Donthineni
2021-06-06  5:00     ` Shanker R Donthineni
2021-06-09 12:51     ` Shanker R Donthineni
2021-05-29 19:25 ` [PATCH v5 6/7] PCI: Enable NO_BUS_RESET quirk for Nvidia GPUs Amey Narkhede
2021-05-29 19:25 ` [PATCH v5 7/7] PCI: Change the type of probe argument in reset functions Amey Narkhede
2021-06-02 22:15   ` Shanker R Donthineni

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=87aaf482-dbfe-adaa-eea0-1c6febe6503c@nvidia.com \
    --to=sdonthineni@nvidia.com \
    --cc=alex.williamson@redhat.com \
    --cc=ameynarkhede03@gmail.com \
    --cc=bhelgaas@google.com \
    --cc=kw@linux.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-pci@vger.kernel.org \
    --cc=okaya@kernel.org \
    --cc=raphael.norwitz@nutanix.com \
    --subject='Re: [PATCH v5 4/7] PCI/sysfs: Allow userspace to query and set device reset mechanism' \
    /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).