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>

1 files changed, 30 insertions, 19 deletions

diff --git a/kernel/compat.c b/kernel/compat.c
index 8eafe3eb50d9..d52e2ec1deb5 100644
--- a/kernel/compat.c
+++ b/kernel/compat.c
@@ -454,16 +454,16 @@ asmlinkage long compat_sys_waitid(int which, compat_pid_t pid,
 }
 
 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_setaffinity(compat_pid_t pid,
                                              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,