问参数(KM_USER1)的kmap_atomic()

EN

asmlinkage  s32 vir_to_kaddr(unsigned long v,struct p_header_s *head,u32)｛
    struct mm_struct *mm = head->task->mm;
    pgd_t *pgd;
    pmd_t *pmd;
    #ifdef PTRS_PER_PUD
        pud_t *pud;
    #endif
    pte_t *pte;
    struct page *pg;
    s32 ret = 0;
    u32 addr = (u32)v;
    s8 *k_addr ;
    spin_lock(&mm->page_table_lock);
    pgd = pgd_offset(mm,addr);
    if (pgd_none(*pgd))
    {
        ret = -1;
        goto out;
    }
    #ifdef PTRS_PER_PUD
    pud = pud_offset(mm,addr);
    if (pud_none(*pud))
    {
        ret = -2;
        goto out;
    }
    pmd = pud_offset(pud,addr);
    #else
    pmd = pmd_offset(pgd,addr);
    #endif
    if (pmd_none(*pmd))
    {
        ret = -3;
        goto out;
    }
    pte = pte_offset_map(pmd,addr);
    if (pte_present(*pte))
    {
        pg = pte_page(*pte);
        if (IS_ERR(pg))
        {
            ret = -4;
            goto out;
        }
        pte_unmap(pte);
    }
    else if (pte_none(*pte))
    {
        pte_unmap(pte);
        ret = -5;
        goto out;
    }
    k_addr = kmap_atomic(pg,KM_USER1)+(addr&(PAGE_SIZE-1));
    ret = memcpy(k_addr,head->v_buf);
    kunmap_atomic(k_)addr,KM_USER1);
    if (ret )
    {
        ret = -6;
    }
    out:
        spin_unlock(&mm->page_table_lock);
        return ret;
}