Re: [RFC][PATCH v4 1/4] alsa: jack: implement software jack injection via debugfs

On Mon, 11 Jan 2021 14:05:54 +0100, Hui Wang wrote:

+static ssize_t sw_inject_enable_read(struct file *file,

• 		     char __user *to, size_t count, loff_t *ppos)
  

+{

• struct snd_jack_kctl *jack_kctl = file->private_data;
• char *buf;
• int len, ret;
• buf = kvzalloc(PAGE_SIZE, GFP_KERNEL);
• if (!buf)

• return -ENOMEM;
  

• len = scnprintf(buf, PAGE_SIZE, "%s: %s\t\t%s: %i\n", "Jack", jack_kctl->kctl->id.name,

• 	"Inject Enabled", jack_kctl->sw_inject_enable);
  

• ret = simple_read_from_buffer(to, count, ppos, buf, len);

For this size of a string buffer, you don't need to allocate via kvmalloc(). It can be on stack.

+static ssize_t sw_inject_enable_write(struct file *file,

• 		      const char __user *from, size_t count, loff_t *ppos)
  

+{

• struct snd_jack_kctl *jack_kctl = file->private_data;
• char *buf;
• int ret, err;
• unsigned long enable;
• buf = kvzalloc(count, GFP_KERNEL);
• if (!buf)

• return -ENOMEM;
  

• ret = simple_write_to_buffer(buf, count, ppos, from, count);
• err = kstrtoul(buf, 0, &enable);

Ditto, it's just a single number and cannot be that big. (Also jackin_inject_write(), too.)

thanks,

Takashi