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Commit 328be395 authored by Dan Carpenter's avatar Dan Carpenter Committed by Greg Kroah-Hartman
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TTY/n_gsm: potential double lock 



In gsm_dlci_data_kick() we call gsm_dlci_data_sweep() with the
"gsm->tx_lock" held so we can't lock it again inside
gsm_dlci_data_sweep().  I removed that lock from and added one to
gsmld_write_wakeup() instead.  The sweep function is only called from
those two places.

Signed-off-by: default avatarDan Carpenter <error27@gmail.com>
Acked-by: default avatarAlan Cox <alan@linux.intel.com>
Cc: stable <stable@kernel.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
parent e59e2bd9

drivers/char/n_gsm.c

+5 −4
Original line number Diff line number Diff line
@@ -904,9 +904,7 @@ static void gsm_dlci_data_sweep(struct gsm_mux *gsm) 
	int len;

	/* Priority ordering: We should do priority with RR of the groups */

	int i = 1;

	unsigned long flags;



	spin_lock_irqsave(&gsm->tx_lock, flags);

	while (i < NUM_DLCI) {

		struct gsm_dlci *dlci;
@@ -927,7 +925,6 @@ static void gsm_dlci_data_sweep(struct gsm_mux *gsm) 
		if (len == 0)

			i++;

	}

	spin_unlock_irqrestore(&gsm->tx_lock, flags);

}



/**
@@ -2230,12 +2227,16 @@ static int gsmld_open(struct tty_struct *tty) 
static void gsmld_write_wakeup(struct tty_struct *tty)

{

	struct gsm_mux *gsm = tty->disc_data;

	unsigned long flags;



	/* Queue poll */

	clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);

	gsm_data_kick(gsm);

	if (gsm->tx_bytes < TX_THRESH_LO)

	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);

	}

}



/**