Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753889Ab2JNOlk (ORCPT ); Sun, 14 Oct 2012 10:41:40 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:46052 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753709Ab2JNOlg (ORCPT ); Sun, 14 Oct 2012 10:41:36 -0400 Message-Id: <20121014143535.274492595@decadent.org.uk> User-Agent: quilt/0.60-1 Date: Sun, 14 Oct 2012 15:35:44 +0100 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Russ Gorby , "Yin, Fengwei" , Alan Cox , Greg Kroah-Hartman Subject: [ 011/147] n_gsm: added interlocking for gsm_data_lock for certain code paths In-Reply-To: <20121014143533.742627615@decadent.org.uk> X-SA-Exim-Connect-IP: 77.75.106.1 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2422 Lines: 72 3.2-stable review patch. If anyone has any objections, please let me know. ------------------ From: Russ Gorby commit 5e44708f75b0f8712da715d6babb0c21089b2317 upstream. 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 Signed-off-by: Greg Kroah-Hartman Signed-off-by: Ben Hutchings --- drivers/tty/n_gsm.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) 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); } /** -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/