Function sys_sched_setaffinity

components/lwp/lwp_syscall.c:8560–8601

* @brief Set the CPU affinity mask of a process. * * This function sets the CPU affinity mask for a specified process. The affinity mask determines which CPUs the * process is allowed to execute on. The process will be restricted to the CPUs specified in the mask. * * @param[in] pid The process ID of the process whose CPU affinity is to be set. If the `pid` is `0`, the *

 * @see sys_sched_getaffinity(), sys_setcpu()
 */
sysret_t sys_sched_setaffinity(pid_t pid, size_t size, void *set)
{
    void *kset = RT_NULL;

    if (size <= 0 || size > sizeof(cpu_set_t))
    {
        return -EINVAL;
    }
    if (!lwp_user_accessable((void *)set, size))
        return -EFAULT;

    kset = kmem_get(size);
    if (kset == RT_NULL)
    {
        return -ENOMEM;
    }

    if (lwp_get_from_user(kset, set, size) != size)
    {
        kmem_put(kset);
        return -EINVAL;
    }

    for (int i = 0;i < size * 8; i++)
    {
        if (CPU_ISSET_S(i, size, kset))
        {
            kmem_put(kset);

            /**
             * yes it's tricky.
             * But when we talk about 'pid' from GNU libc, it's the 'task-id'
             * aka 'thread->tid' known in kernel.
             */
            return lwp_setaffinity(pid, i);
        }
    }

    kmem_put(kset);

    return -1;
}

/**
 * @brief Get the CPU affinity mask of a process.