Issue
Usually proc entries are deleting inside function with __exit attribute. How can I delete it on user request?
I've tired to call remove_proc_entry inside write callback, but the kernel crushes there.
I cannot just remove module as it manages several proc entries at a time. I'm just want to delete that one for whom i'm telling "delete".
static int my_write(struct file *file, const char __user *userbuff,
size_t len, loff_t *ppos)
{
struct seq_file *seqf = file->private_data;
struct *my_data = seqf->private;
char *buff;
int retval;
retval = -EINVAL;
if (!userbuff || len > PAGE_SIZE)
return -EINVAL;
buff = kzalloc((len + 1), GFP_KERNEL);
if (!buff)
return -ENOMEM;
if (copy_from_user(buff, userbuff, len))
goto out;
buff[len] = '\0';
if (!strncmp("delete", buff, 6)) {
/* Cannot use remove_proc_entry inside that write callback. */
retval = 0;
}
if (!retval)
retval = len;
else
printk("Usage: echo delete > /proc/my_proc to delete that entry.\n");
return retval;
}
static const struct file_operations my_proc_fops = {
.open = my_proc_open,
.read = seq_read,
.write = my_write,
.llseek = seq_lseek,
.release = single_release,
};
Solution
Thanks! I've made it via schedule_work.
struct my_data {
/* data */
struct work_struct remove_proc_work;
};
static void remove_proc_work_handler(struct work_struct *work)
{
struct my_data *data;
data = container_of(work, struct my_data, remove_proc_work);
/* call remove_proc_entry */
}
static void init_data(struct my_data *data)
{
/* init data */
INIT_WORK(&data->remove_proc_work, remove_proc_work_handler);
}
static int my_write(struct file *file, const char __user *userbuff,
size_t len, loff_t *ppos)
{
struct seq_file *seqf = file->private_data;
struct my_data *data = seqf->private;
char *buff;
int retval;
retval = -EINVAL;
if (!userbuff || len > PAGE_SIZE)
return -EINVAL;
buff = kzalloc((len + 1), GFP_KERNEL);
if (!buff)
return -ENOMEM;
if (copy_from_user(buff, userbuff, len))
goto out;
buff[len] = '\0';
if (!strncmp("delete", buff, 6)) {
/* Cannot use remove_proc_entry inside that write callback. */
schedule_work(&data->remove_proc_work);
retval = 0;
}
if (!retval)
retval = len;
else
printk("Usage: echo delete > /proc/my_proc to delete that entry.\n");
return retval;
}
static const struct file_operations my_proc_fops = {
.open = my_proc_open,
.read = seq_read,
.write = my_write,
.llseek = seq_lseek,
.release = single_release,
};
Answered By - Ivan Morozko