From: Simon Derr <simon.derr@bull.net>
This fixes a possible race between two threads of a single process in
cpuset_tasks_read().
It is mostly the same issue as the one that was in sysfs.
Signed-Off-By: Simon Derr <simon.derr@bull.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
---
25-akpm/kernel/cpuset.c | 13 ++++++++++---
1 files changed, 10 insertions(+), 3 deletions(-)
diff -puN kernel/cpuset.c~cpusets-fix-possible-race-in-cpuset_tasks_read kernel/cpuset.c
--- 25/kernel/cpuset.c~cpusets-fix-possible-race-in-cpuset_tasks_read 2004-09-11 17:26:05.822749504 -0700
+++ 25-akpm/kernel/cpuset.c 2004-09-11 17:26:05.826748896 -0700
@@ -1083,20 +1083,27 @@ err0:
static ssize_t cpuset_tasks_read(struct file *file, char __user *buf,
size_t nbytes, loff_t *ppos)
{
- struct ctr_struct *ctr = (struct ctr_struct *)file->private_data;
+ struct ctr_struct *ctr;
+ down(&cpuset_sem);
+ ctr = (struct ctr_struct *)file->private_data;
/* allocate buffer and fill it on first call to read() */
if (!ctr) {
ctr = cpuset_tasks_mkctr(file);
- if (!ctr)
+ if (!ctr) {
+ up(&cpuset_sem);
return -ENOMEM;
+ }
}
if (*ppos + nbytes > ctr->bufsz)
nbytes = ctr->bufsz - *ppos;
- if (copy_to_user(buf, ctr->buf + *ppos, nbytes))
+ if (copy_to_user(buf, ctr->buf + *ppos, nbytes)) {
+ up(&cpuset_sem);
return -EFAULT;
+ }
*ppos += nbytes;
+ up(&cpuset_sem);
return nbytes;
}
_