From c42b4e6501cdaabee8cc292ae1ef0f66bf4825c1 Mon Sep 17 00:00:00 2001 From: Greg Kroah-Hartman Date: Mon, 25 Nov 2013 18:30:21 -0800 Subject: [PATCH] Revert "n_gsm: race between ld close and gsmtty open" This reverts commit c284ee2cf12b55fa8496b2d098bf0938688f1c1c. Turns out the locking was incorrect. Reported-by: Fengguang Wu Cc: Chao Bi Signed-off-by: Greg Kroah-Hartman --- drivers/tty/n_gsm.c | 37 ++++++++++--------------------------- 1 file changed, 10 insertions(+), 27 deletions(-) diff --git a/drivers/tty/n_gsm.c b/drivers/tty/n_gsm.c index 069bfd654485..c0f76da55304 100644 --- a/drivers/tty/n_gsm.c +++ b/drivers/tty/n_gsm.c @@ -2054,11 +2054,9 @@ void gsm_cleanup_mux(struct gsm_mux *gsm) dlci->state == DLCI_CLOSED); } /* Free up any link layer users */ - spin_lock(&gsm->lock); for (i = 0; i < NUM_DLCI; i++) if (gsm->dlci[i]) gsm_dlci_release(gsm->dlci[i]); - spin_unlock(&gsm->lock); /* Now wipe the queues */ list_for_each_entry_safe(txq, ntxq, &gsm->tx_list, list) kfree(txq); @@ -2911,33 +2909,23 @@ static int gsmtty_install(struct tty_driver *driver, struct tty_struct *tty) This is ok from a locking perspective as we don't have to worry about this if DLCI0 is lost */ - spin_lock(&gsm->lock); - if (gsm->dlci[0] && gsm->dlci[0]->state != DLCI_OPEN) { - spin_unlock(&gsm->lock); + if (gsm->dlci[0] && gsm->dlci[0]->state != DLCI_OPEN) return -EL2NSYNC; - } dlci = gsm->dlci[line]; if (dlci == NULL) { alloc = true; dlci = gsm_dlci_alloc(gsm, line); } - if (dlci == NULL) { - spin_unlock(&gsm->lock); + if (dlci == NULL) return -ENOMEM; - } ret = tty_port_install(&dlci->port, driver, tty); if (ret) { if (alloc) dlci_put(dlci); - spin_unlock(&gsm->lock); return ret; } - dlci_get(dlci); - dlci_get(gsm->dlci[0]); - mux_get(gsm); tty->driver_data = dlci; - spin_unlock(&gsm->lock); return 0; } @@ -2948,6 +2936,9 @@ static int gsmtty_open(struct tty_struct *tty, struct file *filp) struct tty_port *port = &dlci->port; port->count++; + dlci_get(dlci); + dlci_get(dlci->gsm->dlci[0]); + mux_get(dlci->gsm); tty_port_tty_set(port, tty); dlci->modem_rx = 0; @@ -2974,7 +2965,7 @@ static void gsmtty_close(struct tty_struct *tty, struct file *filp) mutex_unlock(&dlci->mutex); gsm = dlci->gsm; if (tty_port_close_start(&dlci->port, tty, filp) == 0) - return; + goto out; gsm_dlci_begin_close(dlci); if (test_bit(ASYNCB_INITIALIZED, &dlci->port.flags)) { if (C_HUPCL(tty)) @@ -2982,7 +2973,10 @@ static void gsmtty_close(struct tty_struct *tty, struct file *filp) } tty_port_close_end(&dlci->port, tty); tty_port_tty_set(&dlci->port, NULL); - return; +out: + dlci_put(dlci); + dlci_put(gsm->dlci[0]); + mux_put(gsm); } static void gsmtty_hangup(struct tty_struct *tty) @@ -3159,16 +3153,6 @@ static int gsmtty_break_ctl(struct tty_struct *tty, int state) return gsmtty_modem_update(dlci, encode); } -static void gsmtty_remove(struct tty_driver *driver, struct tty_struct *tty) -{ - struct gsm_dlci *dlci = tty->driver_data; - struct gsm_mux *gsm = dlci->gsm; - - dlci_put(dlci); - dlci_put(gsm->dlci[0]); - mux_put(gsm); - driver->ttys[tty->index] = NULL; -} /* Virtual ttys for the demux */ static const struct tty_operations gsmtty_ops = { @@ -3188,7 +3172,6 @@ static const struct tty_operations gsmtty_ops = { .tiocmget = gsmtty_tiocmget, .tiocmset = gsmtty_tiocmset, .break_ctl = gsmtty_break_ctl, - .remove = gsmtty_remove, }; -- 2.20.1