On Thu, 8 Apr 2021 16:13:20 +0200
Daniel Bristot de Oliveira <bris...@redhat.com> wrote:
> +/**
> + * hwlat_mode_write - Write function for "mode" entry
> + * @filp: The active open file structure
> + * @ubuf: The user buffer that contains the value to write
> + * @cnt: The maximum number of bytes to write to "file"
> + * @ppos: The current position in @file
> + *
> + * This function provides a write implementation for the "mode" interface
> + * to the hardware latency detector. hwlatd has different operation modes.
> + * The "none" sets the allowed cpumask for a single hwlatd thread at the
> + * startup and lets the scheduler handle the migration. The default mode is
> + * the "round-robin" one, in which a single hwlatd thread runs, migrating
> + * among the allowed CPUs in a round-robin fashion.
> + */
> +static ssize_t hwlat_mode_write(struct file *filp, const char __user *ubuf,
> + size_t cnt, loff_t *ppos)
> +{
> + const char *mode;
> + char buf[64];
> + int ret;
> + int i;
> +
> + if (hwlat_busy)
> + return -EBUSY;
So we can't switch modes while running?
Also, with this implemented, you can remove the disable_migrate variable,
and just switch the mode to NONE when it's detected that the affinity mask
of the thread has been changed.
-- Steve
> +
> + if (cnt >= sizeof(buf))
> + return -EINVAL;
> +
> + if (copy_from_user(buf, ubuf, cnt))
> + return -EFAULT;
> +
> + buf[cnt] = 0;
> +
> + mode = strstrip(buf);
> +
> + ret = -EINVAL;
> +
> + for (i = 0; i < MODE_MAX; i++) {
> + if (strcmp(mode, thread_mode_str[i]) == 0) {
> + hwlat_data.thread_mode = i;
> + ret = cnt;
> + }
> + }
> +
> + *ppos += cnt;
> +
> + return cnt;
> +}
> +
> +
