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SubjectRe: [PATCH][RESEND 3] disassociate_ctty SMP fix
On Tue, 4 Feb 2003, Rik van Riel wrote:

> the following patch, against today's BK tree, fixes a small
> SMP race in disassociate_ctty. This function gets called
> from do_exit, without the BKL held.

Here's a better one, this one does the same fix not only
in disassociate_ctty() but also in do_tty_hangup()

If we're lucky it might fix:
http://bugme.osdl.org/show_bug.cgi?id=54

Please apply. Thank you,

Rik

===== drivers/char/tty_io.c 1.55 vs edited =====
--- 1.55/drivers/char/tty_io.c Tue Jan 14 23:37:20 2003
+++ edited/drivers/char/tty_io.c Tue Feb 4 23:02:52 2003
@@ -425,19 +425,21 @@
*/
void do_tty_hangup(void *data)
{
- struct tty_struct *tty = (struct tty_struct *) data;
+ struct tty_struct *tty;
struct file * cons_filp = NULL;
struct task_struct *p;
struct list_head *l;
struct pid *pid;
int closecount = 0, n;

- if (!tty)
- return;
-
/* inuse_filps is protected by the single kernel lock */
lock_kernel();
-
+ tty = (struct tty_struct *) data;
+ if (!tty) {
+ unlock_kernel();
+ return;
+ }
+
check_tty_count(tty, "do_tty_hangup");
file_list_lock();
for (l = tty->tty_files.next; l != &tty->tty_files; l = l->next) {
@@ -571,7 +573,7 @@
*/
void disassociate_ctty(int on_exit)
{
- struct tty_struct *tty = current->tty;
+ struct tty_struct *tty;
struct task_struct *p;
struct list_head *l;
struct pid *pid;
@@ -579,6 +581,7 @@

lock_kernel();

+ tty = current->tty;
if (tty) {
tty_pgrp = tty->pgrp;
if (on_exit && tty->driver.type != TTY_DRIVER_TYPE_PTY)
-
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