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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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