From 5e44708f75b0f8712da715d6babb0c21089b2317 Mon Sep 17 00:00:00 2001 From: Russ Gorby Date: Mon, 13 Aug 2012 13:44:40 +0100 Subject: n_gsm: added interlocking for gsm_data_lock for certain code paths There were some locking holes in the management of the MUX's message queue for 2 code paths: 1) gsmld_write_wakeup 2) receipt of CMD_FCON flow-control message In both cases gsm_data_kick is called w/o locking so it can collide with other other instances of gsm_data_kick (pulling messages tx_tail) or potentially other instances of __gsm_data_queu (adding messages to tx_head) Changed to take the tx_lock in these 2 cases Signed-off-by: Russ Gorby Tested-by: Yin, Fengwei Signed-off-by: Alan Cox Cc: Riding School Signed-off-by: Greg Kroah-Hartman --- drivers/tty/n_gsm.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) (limited to 'drivers/tty/n_gsm.c') diff --git a/drivers/tty/n_gsm.c b/drivers/tty/n_gsm.c index 5f68f2a..0d93e51 100644 --- a/drivers/tty/n_gsm.c +++ b/drivers/tty/n_gsm.c @@ -1205,6 +1205,8 @@ static void gsm_control_message(struct gsm_mux *gsm, unsigned int command, u8 *data, int clen) { u8 buf[1]; + unsigned long flags; + switch (command) { case CMD_CLD: { struct gsm_dlci *dlci = gsm->dlci[0]; @@ -1225,7 +1227,9 @@ static void gsm_control_message(struct gsm_mux *gsm, unsigned int command, gsm->constipated = 0; gsm_control_reply(gsm, CMD_FCON, NULL, 0); /* Kick the link in case it is idling */ + spin_lock_irqsave(&gsm->tx_lock, flags); gsm_data_kick(gsm); + spin_unlock_irqrestore(&gsm->tx_lock, flags); break; case CMD_FCOFF: /* Modem wants us to STFU */ @@ -2392,12 +2396,12 @@ static void gsmld_write_wakeup(struct tty_struct *tty) /* Queue poll */ clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags); + spin_lock_irqsave(&gsm->tx_lock, flags); gsm_data_kick(gsm); if (gsm->tx_bytes < TX_THRESH_LO) { - spin_lock_irqsave(&gsm->tx_lock, flags); gsm_dlci_data_sweep(gsm); - spin_unlock_irqrestore(&gsm->tx_lock, flags); } + spin_unlock_irqrestore(&gsm->tx_lock, flags); } /** -- cgit v1.1