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    Subject[PATCH 1/8] cpumask: convert kernel/compat.c
    Impact: Reduce stack usage, use new cpumask API.

    Straightforward conversion; cpumasks' size is given by cpumask_size() (now
    a variable rather than fixed) and on-stack cpu masks use cpumask_var_t.

    Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
    Signed-off-by: Mike Travis <travis@sgi.com>
    ---
    kernel/compat.c | 49 ++++++++++++++++++++++++++++++-------------------
    1 file changed, 30 insertions(+), 19 deletions(-)

    --- linux-2.6.28.orig/kernel/compat.c
    +++ linux-2.6.28/kernel/compat.c
    @@ -454,16 +454,16 @@ asmlinkage long compat_sys_waitid(int wh
    }

    static int compat_get_user_cpu_mask(compat_ulong_t __user *user_mask_ptr,
    - unsigned len, cpumask_t *new_mask)
    + unsigned len, struct cpumask *new_mask)
    {
    unsigned long *k;

    - if (len < sizeof(cpumask_t))
    - memset(new_mask, 0, sizeof(cpumask_t));
    - else if (len > sizeof(cpumask_t))
    - len = sizeof(cpumask_t);
    + if (len < cpumask_size())
    + memset(new_mask, 0, cpumask_size());
    + else if (len > cpumask_size())
    + len = cpumask_size();

    - k = cpus_addr(*new_mask);
    + k = cpumask_bits(new_mask);
    return compat_get_bitmap(k, user_mask_ptr, len * 8);
    }

    @@ -471,40 +471,51 @@ asmlinkage long compat_sys_sched_setaffi
    unsigned int len,
    compat_ulong_t __user *user_mask_ptr)
    {
    - cpumask_t new_mask;
    + cpumask_var_t new_mask;
    int retval;

    - retval = compat_get_user_cpu_mask(user_mask_ptr, len, &new_mask);
    + if (!alloc_cpumask_var(&new_mask, GFP_KERNEL))
    + return -ENOMEM;
    +
    + retval = compat_get_user_cpu_mask(user_mask_ptr, len, new_mask);
    if (retval)
    - return retval;
    + goto out;

    - return sched_setaffinity(pid, &new_mask);
    + retval = sched_setaffinity(pid, new_mask);
    +out:
    + free_cpumask_var(new_mask);
    + return retval;
    }

    asmlinkage long compat_sys_sched_getaffinity(compat_pid_t pid, unsigned int len,
    compat_ulong_t __user *user_mask_ptr)
    {
    int ret;
    - cpumask_t mask;
    + cpumask_var_t mask;
    unsigned long *k;
    - unsigned int min_length = sizeof(cpumask_t);
    + unsigned int min_length = cpumask_size();

    - if (NR_CPUS <= BITS_PER_COMPAT_LONG)
    + if (nr_cpu_ids <= BITS_PER_COMPAT_LONG)
    min_length = sizeof(compat_ulong_t);

    if (len < min_length)
    return -EINVAL;

    - ret = sched_getaffinity(pid, &mask);
    + if (!alloc_cpumask_var(&mask, GFP_KERNEL))
    + return -ENOMEM;
    +
    + ret = sched_getaffinity(pid, mask);
    if (ret < 0)
    - return ret;
    + goto out;

    - k = cpus_addr(mask);
    + k = cpumask_bits(mask);
    ret = compat_put_bitmap(user_mask_ptr, k, min_length * 8);
    - if (ret)
    - return ret;
    + if (ret == 0)
    + ret = min_length;

    - return min_length;
    +out:
    + free_cpumask_var(mask);
    + return ret;
    }

    int get_compat_itimerspec(struct itimerspec *dst,
    --


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