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SubjectRe: [PATCH v5 4/7] PCI/sysfs: Allow userspace to query and set device reset mechanism
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.

[...]
> +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.

[...]
> +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.

Krzysztof

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