Commit acdab4cb authored by Fedor Pchelkin's avatar Fedor Pchelkin Committed by Greg Kroah-Hartman
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Revert "tty: n_gsm: avoid call of sleeping functions from atomic context" 



This reverts commit 902e02ea.

The above commit is reverted as the usage of tx_mutex seems not to solve
the problem described in 902e02ea ("tty: n_gsm: avoid call of sleeping
functions from atomic context") and just moves the bug to another place.

Signed-off-by: default avatarFedor Pchelkin <pchelkin@ispras.ru>
Signed-off-by: default avatarAlexey Khoroshilov <khoroshilov@ispras.ru>
Reviewed-by: default avatarDaniel Starke <daniel.starke@siemens.com>
Link: https://lore.kernel.org/r/20221008110221.13645-2-pchelkin@ispras.ru


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 4561d800

drivers/tty/n_gsm.c

+29 −24
Original line number Diff line number Diff line
@@ -264,7 +264,7 @@ struct gsm_mux { 
	bool constipated;		/* Asked by remote to shut up */

	bool has_devices;		/* Devices were registered */



	struct mutex tx_mutex;

	spinlock_t tx_lock;

	unsigned int tx_bytes;		/* TX data outstanding */

#define TX_THRESH_HI		8192

#define TX_THRESH_LO		2048
@@ -700,6 +700,7 @@ static int gsm_send(struct gsm_mux *gsm, int addr, int cr, int control) 
	struct gsm_msg *msg;

	u8 *dp;

	int ocr;

	unsigned long flags;



	msg = gsm_data_alloc(gsm, addr, 0, control);

	if (!msg)
@@ -721,10 +722,10 @@ static int gsm_send(struct gsm_mux *gsm, int addr, int cr, int control) 


	gsm_print_packet("Q->", addr, cr, control, NULL, 0);



	mutex_lock(&gsm->tx_mutex);

	spin_lock_irqsave(&gsm->tx_lock, flags);

	list_add_tail(&msg->list, &gsm->tx_ctrl_list);

	gsm->tx_bytes += msg->len;

	mutex_unlock(&gsm->tx_mutex);

	spin_unlock_irqrestore(&gsm->tx_lock, flags);

	gsmld_write_trigger(gsm);



	return 0;
@@ -749,7 +750,7 @@ static void gsm_dlci_clear_queues(struct gsm_mux *gsm, struct gsm_dlci *dlci) 
	spin_unlock_irqrestore(&dlci->lock, flags);



	/* Clear data packets in MUX write queue */

	mutex_lock(&gsm->tx_mutex);

	spin_lock_irqsave(&gsm->tx_lock, flags);

	list_for_each_entry_safe(msg, nmsg, &gsm->tx_data_list, list) {

		if (msg->addr != addr)

			continue;
@@ -757,7 +758,7 @@ static void gsm_dlci_clear_queues(struct gsm_mux *gsm, struct gsm_dlci *dlci) 
		list_del(&msg->list);

		kfree(msg);

	}

	mutex_unlock(&gsm->tx_mutex);

	spin_unlock_irqrestore(&gsm->tx_lock, flags);

}



/**
@@ -1043,9 +1044,10 @@ static void __gsm_data_queue(struct gsm_dlci *dlci, struct gsm_msg *msg) 


static void gsm_data_queue(struct gsm_dlci *dlci, struct gsm_msg *msg)

{

	mutex_lock(&dlci->gsm->tx_mutex);

	unsigned long flags;

	spin_lock_irqsave(&dlci->gsm->tx_lock, flags);

	__gsm_data_queue(dlci, msg);

	mutex_unlock(&dlci->gsm->tx_mutex);

	spin_unlock_irqrestore(&dlci->gsm->tx_lock, flags);

}



/**
@@ -1057,7 +1059,7 @@ static void gsm_data_queue(struct gsm_dlci *dlci, struct gsm_msg *msg) 
 *	is data. Keep to the MRU of the mux. This path handles the usual tty

 *	interface which is a byte stream with optional modem data.

 *

 *	Caller must hold the tx_mutex of the mux.

 *	Caller must hold the tx_lock of the mux.

 */



static int gsm_dlci_data_output(struct gsm_mux *gsm, struct gsm_dlci *dlci)
@@ -1117,7 +1119,7 @@ static int gsm_dlci_data_output(struct gsm_mux *gsm, struct gsm_dlci *dlci) 
 *	is data. Keep to the MRU of the mux. This path handles framed data

 *	queued as skbuffs to the DLCI.

 *

 *	Caller must hold the tx_mutex of the mux.

 *	Caller must hold the tx_lock of the mux.

 */



static int gsm_dlci_data_output_framed(struct gsm_mux *gsm,
@@ -1133,7 +1135,7 @@ static int gsm_dlci_data_output_framed(struct gsm_mux *gsm, 
	if (dlci->adaption == 4)

		overhead = 1;



	/* dlci->skb is locked by tx_mutex */

	/* dlci->skb is locked by tx_lock */

	if (dlci->skb == NULL) {

		dlci->skb = skb_dequeue_tail(&dlci->skb_list);

		if (dlci->skb == NULL)
@@ -1187,7 +1189,7 @@ static int gsm_dlci_data_output_framed(struct gsm_mux *gsm, 
 *	Push an empty frame in to the transmit queue to update the modem status

 *	bits and to transmit an optional break.

 *

 *	Caller must hold the tx_mutex of the mux.

 *	Caller must hold the tx_lock of the mux.

 */



static int gsm_dlci_modem_output(struct gsm_mux *gsm, struct gsm_dlci *dlci,
@@ -1301,12 +1303,13 @@ static int gsm_dlci_data_sweep(struct gsm_mux *gsm) 


static void gsm_dlci_data_kick(struct gsm_dlci *dlci)

{

	unsigned long flags;

	int sweep;



	if (dlci->constipated)

		return;



	mutex_lock(&dlci->gsm->tx_mutex);

	spin_lock_irqsave(&dlci->gsm->tx_lock, flags);

	/* If we have nothing running then we need to fire up */

	sweep = (dlci->gsm->tx_bytes < TX_THRESH_LO);

	if (dlci->gsm->tx_bytes == 0) {
@@ -1317,7 +1320,7 @@ static void gsm_dlci_data_kick(struct gsm_dlci *dlci) 
	}

	if (sweep)

		gsm_dlci_data_sweep(dlci->gsm);

	mutex_unlock(&dlci->gsm->tx_mutex);

	spin_unlock_irqrestore(&dlci->gsm->tx_lock, flags);

}



/*
@@ -2029,13 +2032,14 @@ static void gsm_dlci_command(struct gsm_dlci *dlci, const u8 *data, int len) 
static void gsm_kick_timeout(struct work_struct *work)

{

	struct gsm_mux *gsm = container_of(work, struct gsm_mux, kick_timeout.work);

	unsigned long flags;

	int sent = 0;



	mutex_lock(&gsm->tx_mutex);

	spin_lock_irqsave(&gsm->tx_lock, flags);

	/* If we have nothing running then we need to fire up */

	if (gsm->tx_bytes < TX_THRESH_LO)

		sent = gsm_dlci_data_sweep(gsm);

	mutex_unlock(&gsm->tx_mutex);

	spin_unlock_irqrestore(&gsm->tx_lock, flags);



	if (sent && debug & DBG_DATA)

		pr_info("%s TX queue stalled\n", __func__);
@@ -2565,7 +2569,6 @@ static void gsm_free_mux(struct gsm_mux *gsm) 
			break;

		}

	}

	mutex_destroy(&gsm->tx_mutex);

	mutex_destroy(&gsm->mutex);

	kfree(gsm->txframe);

	kfree(gsm->buf);
@@ -2637,7 +2640,6 @@ static struct gsm_mux *gsm_alloc_mux(void) 
	}

	spin_lock_init(&gsm->lock);

	mutex_init(&gsm->mutex);

	mutex_init(&gsm->tx_mutex);

	kref_init(&gsm->ref);

	INIT_LIST_HEAD(&gsm->tx_ctrl_list);

	INIT_LIST_HEAD(&gsm->tx_data_list);
@@ -2646,6 +2648,7 @@ static struct gsm_mux *gsm_alloc_mux(void) 
	INIT_WORK(&gsm->tx_work, gsmld_write_task);

	init_waitqueue_head(&gsm->event);

	spin_lock_init(&gsm->control_lock);

	spin_lock_init(&gsm->tx_lock);



	gsm->t1 = T1;

	gsm->t2 = T2;
@@ -2670,7 +2673,6 @@ static struct gsm_mux *gsm_alloc_mux(void) 
	}

	spin_unlock(&gsm_mux_lock);

	if (i == MAX_MUX) {

		mutex_destroy(&gsm->tx_mutex);

		mutex_destroy(&gsm->mutex);

		kfree(gsm->txframe);

		kfree(gsm->buf);
@@ -2826,16 +2828,17 @@ static void gsmld_write_trigger(struct gsm_mux *gsm) 
static void gsmld_write_task(struct work_struct *work)

{

	struct gsm_mux *gsm = container_of(work, struct gsm_mux, tx_work);

	unsigned long flags;

	int i, ret;



	/* All outstanding control channel and control messages and one data

	 * frame is sent.

	 */

	ret = -ENODEV;

	mutex_lock(&gsm->tx_mutex);

	spin_lock_irqsave(&gsm->tx_lock, flags);

	if (gsm->tty)

		ret = gsm_data_kick(gsm);

	mutex_unlock(&gsm->tx_mutex);

	spin_unlock_irqrestore(&gsm->tx_lock, flags);



	if (ret >= 0)

		for (i = 0; i < NUM_DLCI; i++)
@@ -3042,6 +3045,7 @@ static ssize_t gsmld_write(struct tty_struct *tty, struct file *file, 
			   const unsigned char *buf, size_t nr)

{

	struct gsm_mux *gsm = tty->disc_data;

	unsigned long flags;

	int space;

	int ret;
@@ -3049,13 +3053,13 @@ static ssize_t gsmld_write(struct tty_struct *tty, struct file *file, 
		return -ENODEV;



	ret = -ENOBUFS;

	mutex_lock(&gsm->tx_mutex);

	spin_lock_irqsave(&gsm->tx_lock, flags);

	space = tty_write_room(tty);

	if (space >= nr)

		ret = tty->ops->write(tty, buf, nr);

	else

		set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);

	mutex_unlock(&gsm->tx_mutex);

	spin_unlock_irqrestore(&gsm->tx_lock, flags);



	return ret;

}
@@ -3352,13 +3356,14 @@ static struct tty_ldisc_ops tty_ldisc_packet = { 
static void gsm_modem_upd_via_data(struct gsm_dlci *dlci, u8 brk)

{

	struct gsm_mux *gsm = dlci->gsm;

	unsigned long flags;



	if (dlci->state != DLCI_OPEN || dlci->adaption != 2)

		return;



	mutex_lock(&gsm->tx_mutex);

	spin_lock_irqsave(&gsm->tx_lock, flags);

	gsm_dlci_modem_output(gsm, dlci, brk);

	mutex_unlock(&gsm->tx_mutex);

	spin_unlock_irqrestore(&gsm->tx_lock, flags);

}



/**