[PATCH] cpuset crapectomy

[linux-2.6] / kernel / cpuset.c

diff --git a/kernel/cpuset.c b/kernel/cpuset.c
index 407b5f0a8c8eeed2aea648b08748771dd284b3d7..45a5719a01047b2355a6eaffe4f1b75c3e22d915 100644 (file)
--- a/kernel/cpuset.c
+++ b/kernel/cpuset.c
@@ -180,6 +180,8 @@ static struct super_block *cpuset_sb = NULL;
  */
 
 static DECLARE_MUTEX(cpuset_sem);
+static struct task_struct *cpuset_sem_owner;
+static int cpuset_sem_depth;
 
 /*
  * The global cpuset semaphore cpuset_sem can be needed by the
@@ -200,16 +202,19 @@ static DECLARE_MUTEX(cpuset_sem);
 
 static inline void cpuset_down(struct semaphore *psem)
 {
-       if (current->cpuset_sem_nest_depth == 0)
+       if (cpuset_sem_owner != current) {
                down(psem);
-       current->cpuset_sem_nest_depth++;
+               cpuset_sem_owner = current;
+       }
+       cpuset_sem_depth++;
 }
 
 static inline void cpuset_up(struct semaphore *psem)
 {
-       current->cpuset_sem_nest_depth--;
-       if (current->cpuset_sem_nest_depth == 0)
+       if (--cpuset_sem_depth == 0) {
+               cpuset_sem_owner = NULL;
                up(psem);
+       }
 }
 
 /*
@@ -963,8 +968,6 @@ static ssize_t cpuset_common_file_read(struct file *file, char __user *buf,
        char *page;
        ssize_t retval = 0;
        char *s;
-       char *start;
-       size_t n;
 
        if (!(page = (char *)__get_free_page(GFP_KERNEL)))
                return -ENOMEM;
@@ -994,14 +997,7 @@ static ssize_t cpuset_common_file_read(struct file *file, char __user *buf,
        *s++ = '\n';
        *s = '\0';
 
-       /* Do nothing if *ppos is at the eof or beyond the eof. */
-       if (s - page <= *ppos)
-               return 0;
-
-       start = page + *ppos;
-       n = s - start;
-       retval = n - copy_to_user(buf, start, min(n, nbytes));
-       *ppos += retval;
+       retval = simple_read_from_buffer(buf, nbytes, ppos, page, s - page);
 out:
        free_page((unsigned long)page);
        return retval;