forked from Minki/linux
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>
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@ -1205,6 +1205,8 @@ static void gsm_control_message(struct gsm_mux *gsm, unsigned int command,
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u8 *data, int clen)
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{
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u8 buf[1];
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unsigned long flags;
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switch (command) {
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case CMD_CLD: {
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struct gsm_dlci *dlci = gsm->dlci[0];
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@ -1225,7 +1227,9 @@ static void gsm_control_message(struct gsm_mux *gsm, unsigned int command,
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gsm->constipated = 0;
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gsm_control_reply(gsm, CMD_FCON, NULL, 0);
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/* Kick the link in case it is idling */
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spin_lock_irqsave(&gsm->tx_lock, flags);
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gsm_data_kick(gsm);
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spin_unlock_irqrestore(&gsm->tx_lock, flags);
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break;
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case CMD_FCOFF:
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/* Modem wants us to STFU */
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@ -2392,12 +2396,12 @@ static void gsmld_write_wakeup(struct tty_struct *tty)
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/* Queue poll */
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clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
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spin_lock_irqsave(&gsm->tx_lock, flags);
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gsm_data_kick(gsm);
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if (gsm->tx_bytes < TX_THRESH_LO) {
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spin_lock_irqsave(&gsm->tx_lock, flags);
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gsm_dlci_data_sweep(gsm);
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spin_unlock_irqrestore(&gsm->tx_lock, flags);
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}
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spin_unlock_irqrestore(&gsm->tx_lock, flags);
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}
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/**
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