diff options
| author | Russ Gorby <russ.gorby@intel.com> | 2012-08-13 13:44:40 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2012-08-16 12:03:30 -0700 |
| commit | 5e44708f75b0f8712da715d6babb0c21089b2317 (patch) | |
| tree | e5f4f2ecd25649b5d47589ba2cf919c4e92ed222 /drivers/tty/n_gsm.c | |
| parent | 10c6c383e43565c9c6ec07ff8eb2825f8091bdf0 (diff) | |
| download | lwn-5e44708f75b0f8712da715d6babb0c21089b2317.tar.gz lwn-5e44708f75b0f8712da715d6babb0c21089b2317.zip | |
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 <russ.gorby@intel.com>
Tested-by: Yin, Fengwei <fengwei.yin@intel.com>
Signed-off-by: Alan Cox <alan@linux.intel.com>
Cc: Riding School <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/tty/n_gsm.c')
| -rw-r--r-- | drivers/tty/n_gsm.c | 8 |
1 files changed, 6 insertions, 2 deletions
diff --git a/drivers/tty/n_gsm.c b/drivers/tty/n_gsm.c index 5f68f2a70c5c..0d93e51cb23d 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); } /** |