aboutsummaryrefslogtreecommitdiffstats
path: root/drivers/char
diff options
context:
space:
mode:
authorDipankar Sarma <dipankar@in.ibm.com>2006-04-19 01:21:46 -0400
committerLinus Torvalds <torvalds@g5.osdl.org>2006-04-19 12:13:51 -0400
commitca99c1da080345e227cfb083c330a184d42e27f3 (patch)
treee417b4c456ae31dc1dde8027b6be44a1a9f19395 /drivers/char
parentfb30d64568fd8f6a21afef987f11852a109723da (diff)
[PATCH] Fix file lookup without ref
There are places in the kernel where we look up files in fd tables and access the file structure without holding refereces to the file. So, we need special care to avoid the race between looking up files in the fd table and tearing down of the file in another CPU. Otherwise, one might see a NULL f_dentry or such torn down version of the file. This patch fixes those special places where such a race may happen. Signed-off-by: Dipankar Sarma <dipankar@in.ibm.com> Acked-by: "Paul E. McKenney" <paulmck@us.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'drivers/char')
-rw-r--r--drivers/char/tty_io.c8
1 files changed, 6 insertions, 2 deletions
diff --git a/drivers/char/tty_io.c b/drivers/char/tty_io.c
index 841f0bd3eaaf..f07637a8f88f 100644
--- a/drivers/char/tty_io.c
+++ b/drivers/char/tty_io.c
@@ -2723,7 +2723,11 @@ static void __do_SAK(void *arg)
2723 } 2723 }
2724 task_lock(p); 2724 task_lock(p);
2725 if (p->files) { 2725 if (p->files) {
2726 rcu_read_lock(); 2726 /*
2727 * We don't take a ref to the file, so we must
2728 * hold ->file_lock instead.
2729 */
2730 spin_lock(&p->files->file_lock);
2727 fdt = files_fdtable(p->files); 2731 fdt = files_fdtable(p->files);
2728 for (i=0; i < fdt->max_fds; i++) { 2732 for (i=0; i < fdt->max_fds; i++) {
2729 filp = fcheck_files(p->files, i); 2733 filp = fcheck_files(p->files, i);
@@ -2738,7 +2742,7 @@ static void __do_SAK(void *arg)
2738 break; 2742 break;
2739 } 2743 }
2740 } 2744 }
2741 rcu_read_unlock(); 2745 spin_unlock(&p->files->file_lock);
2742 } 2746 }
2743 task_unlock(p); 2747 task_unlock(p);
2744 } while_each_thread(g, p); 2748 } while_each_thread(g, p);