Re: [PATCH] drivers: pnp: proc.c: Handle errors while attaching devices

Leon Romanovsky
2021-04-26T05:04:08Z

On Sun, Apr 25, 2021 at 01:13:01AM +0530, Anupama K Patil wrote:
> isapnp_proc_init() does not look at the return value from
> isapnp_proc_attach_device(). Check for this return value in
> isapnp_proc_detach_device().
>
> Cleanup in isapnp_proc_detach_device and
> isapnp_proc_detach_bus() for cleanup.
>
> Changed sprintf() to the kernel-space function scnprintf() as it returns
> the actual number of bytes written.
>
> Removed unnecessary variables de, e of type 'struct proc_dir_entry' to
> save memory.

What exactly do you fix for such an old code?

>
> Suggested-by: Shuah Khan <skhan@linuxfoundation.org>
> Co-developed-by: B K Karthik <bkkarthik@pesu.pes.edu>
> Signed-off-by: B K Karthik <bkkarthik@pesu.pes.edu>
> Signed-off-by: Anupama K Patil <anupamakpatil123@gmail.com>
> ---
> drivers/pnp/isapnp/proc.c | 40 +++++++++++++++++++++++++++++----------
> 1 file changed, 30 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/pnp/isapnp/proc.c b/drivers/pnp/isapnp/proc.c
> index 785a796430fa..46ebc24175b7 100644
> --- a/drivers/pnp/isapnp/proc.c
> +++ b/drivers/pnp/isapnp/proc.c
> @@ -54,34 +54,54 @@ static const struct proc_ops isapnp_proc_bus_proc_ops = {
> .proc_read = isapnp_proc_bus_read,
> };
>
> +static int isapnp_proc_detach_device(struct pnp_dev *dev)
> +{
> + proc_remove(dev->procent);
> + dev->procent = NULL;
> + return 0;
> +}
> +
> +static int isapnp_proc_detach_bus(struct pnp_card *bus)
> +{
> + proc_remove(bus->procdir);
> + return 0;
> +}

Please don't add one line functions that are called only once and have
return value that no one care about it.

Thanks

> +
> static int isapnp_proc_attach_device(struct pnp_dev *dev)
> {
> struct pnp_card *bus = dev->card;
> - struct proc_dir_entry *de, *e;
> char name[16];
>
> - if (!(de = bus->procdir)) {
> - sprintf(name, "%02x", bus->number);
> - de = bus->procdir = proc_mkdir(name, isapnp_proc_bus_dir);
> - if (!de)
> + if (!bus->procdir) {
> + scnprintf(name, 16, "%02x", bus->number);
> + bus->procdir = proc_mkdir(name, isapnp_proc_bus_dir);
> + if (!bus->procdir)
> return -ENOMEM;
> }
> - sprintf(name, "%02x", dev->number);
> - e = dev->procent = proc_create_data(name, S_IFREG | S_IRUGO, de,
> + scnprintf(name, 16, "%02x", dev->number);
> + dev->procent = proc_create_data(name, S_IFREG | S_IRUGO, bus->procdir,
> &isapnp_proc_bus_proc_ops, dev);
> - if (!e)
> + if (!dev->procent) {
> + isapnp_proc_detach_bus(bus);
> return -ENOMEM;
> - proc_set_size(e, 256);
> + }
> + proc_set_size(dev->procent, 256);
> return 0;
> }
>
> int __init isapnp_proc_init(void)
> {
> struct pnp_dev *dev;
> + int dev_attach;
>
> isapnp_proc_bus_dir = proc_mkdir("bus/isapnp", NULL);
> protocol_for_each_dev(&isapnp_protocol, dev) {
> - isapnp_proc_attach_device(dev);
> + dev_attach = isapnp_proc_attach_device(dev);
> + if (!dev_attach) {
> + pr_info("procfs: pnp: Unable to attach the device, not enough memory");
> + isapnp_proc_detach_device(dev);
> + return -ENOMEM;
> + }
> }
> return 0;
> }
> --
> 2.25.1
>

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