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SubjectRe: [PATCH/RFC] New module refcounting for TTY ldisc

Any comments on this one ?
I'm holding my Bluetooth patches because of this.

Max


On Wed, 25 Dec 2002, Max Krasnyansky wrote
> Folks,
>
> Here is the patch that converts TTY ldisc code to the new
> module refcounting API.
> Tested with Bluetooth UART driver and seemed to work fine.
> Other ldiscs are not affected because their ldisc->owner is
> set to NULL.
>
> If people are ok with it I'll push it to my BK tree along with
> fixed Bluetooth ldisc.
>
> # This is a BitKeeper generated patch for the following project:
> # Project Name: Linux kernel tree
> # This patch format is intended for GNU patch command version 2.5 or higher.
> # This patch includes the following deltas:
> # ChangeSet 1.889 -> 1.890
> # drivers/char/tty_io.c 1.50 -> 1.51
> # include/linux/tty_ldisc.h 1.2 -> 1.3
> #
> # The following is the BitKeeper ChangeSet Log
> # --------------------------------------------
> # 02/12/23 maxk@qualcomm.com 1.890
> # New module refcounting for TTY ldisc
> # --------------------------------------------
> #
> diff -Nru a/drivers/char/tty_io.c b/drivers/char/tty_io.c
> --- a/drivers/char/tty_io.c Wed Dec 25 19:49:53 2002
> +++ b/drivers/char/tty_io.c Wed Dec 25 19:49:53 2002
> @@ -292,6 +292,10 @@
>
> if (tty->ldisc.num == ldisc)
> return 0; /* We are already in the desired discipline */
> +
> + if (!try_module_get(ldiscs[ldisc].owner))
> + return -EINVAL;
> +
> o_ldisc = tty->ldisc;
>
> tty_wait_until_sent(tty, 0);
> @@ -306,9 +310,13 @@
> if (tty->ldisc.open)
> retval = (tty->ldisc.open)(tty);
> if (retval < 0) {
> + module_put(tty->ldisc.owner);
> +
> tty->ldisc = o_ldisc;
> tty->termios->c_line = tty->ldisc.num;
> if (tty->ldisc.open && (tty->ldisc.open(tty) < 0)) {
> + module_put(tty->ldisc.owner);
> +
> tty->ldisc = ldiscs[N_TTY];
> tty->termios->c_line = N_TTY;
> if (tty->ldisc.open) {
> @@ -320,7 +328,10 @@
> tty_name(tty, buf), r);
> }
> }
> + } else {
> + module_put(o_ldisc.owner);
> }
> +
> if (tty->ldisc.num != o_ldisc.num && tty->driver.set_ldisc)
> tty->driver.set_ldisc(tty);
> return retval;
> @@ -489,6 +500,8 @@
> if (tty->ldisc.num != ldiscs[N_TTY].num) {
> if (tty->ldisc.close)
> (tty->ldisc.close)(tty);
> + module_put(tty->ldisc.owner);
> +
> tty->ldisc = ldiscs[N_TTY];
> tty->termios->c_line = N_TTY;
> if (tty->ldisc.open) {
> @@ -1259,6 +1272,8 @@
> */
> if (tty->ldisc.close)
> (tty->ldisc.close)(tty);
> + module_put(tty->ldisc.owner);
> +
> tty->ldisc = ldiscs[N_TTY];
> tty->termios->c_line = N_TTY;
> if (o_tty) {
> diff -Nru a/include/linux/tty_ldisc.h b/include/linux/tty_ldisc.h
> --- a/include/linux/tty_ldisc.h Wed Dec 25 19:49:53 2002
> +++ b/include/linux/tty_ldisc.h Wed Dec 25 19:49:53 2002
> @@ -105,6 +105,7 @@
> char *name;
> int num;
> int flags;
> +
> /*
> * The following routines are called from above.
> */
> @@ -129,6 +130,8 @@
> char *fp, int count);
> int (*receive_room)(struct tty_struct *);
> void (*write_wakeup)(struct tty_struct *);
> +
> + struct module *owner;
> };
>
> #define TTY_LDISC_MAGIC 0x5403
>
> --
>
> Max
>
>

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