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Revert "tty: n_gsm: avoid call of sleeping functions from atomic context"

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commit acdab4cb4ba7e5f94d2b422ebd7bf4bf68178fb2 upstream.

This reverts commit 902e02ea9385373ce4b142576eef41c642703955.

The above commit is reverted as the usage of tx_mutex seems not to solve
the problem described in 902e02ea9385 ("tty: n_gsm: avoid call of sleeping
functions from atomic context") and just moves the bug to another place.

Signed-off-by: Fedor Pchelkin <pchelkin@ispras.ru>
Signed-off-by: Alexey Khoroshilov <khoroshilov@ispras.ru>
Reviewed-by: Daniel Starke <daniel.starke@siemens.com>
Link: https://lore.kernel.org/r/20221008110221.13645-2-pchelkin@ispras.ru
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Fedor Pchelkin 2022-10-08 14:02:20 +03:00 committed by Greg Kroah-Hartman
parent 481f9ed8eb
commit b7f7a0402e
1 changed files with 21 additions and 18 deletions
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39
drivers/tty/n_gsm.c
View File

@ -235,7 +235,7 @@ struct gsm_mux {
int old_c_iflag; /* termios c_iflag value before attach */
bool constipated; /* Asked by remote to shut up */
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
@ -820,14 +820,15 @@ static void __gsm_data_queue(struct gsm_dlci *dlci, struct gsm_msg *msg)
*
* Add data to the transmit queue and try and get stuff moving
* out of the mux tty if not already doing so. Take the
* the gsm tx mutex and dlci lock.
* the gsm tx lock and dlci lock.
*/
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);
}
/**
@ -839,7 +840,7 @@ 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)
@ -902,7 +903,7 @@ 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,
@ -918,7 +919,7 @@ 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)
@ -1018,12 +1019,13 @@ static void 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) {
@ -1034,7 +1036,7 @@ 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);
}
/*
@ -1256,6 +1258,7 @@ static void gsm_control_message(struct gsm_mux *gsm, unsigned int command,
const u8 *data, int clen)
{
u8 buf[1];
unsigned long flags;
switch (command) {
case CMD_CLD: {
@ -1277,9 +1280,9 @@ static void gsm_control_message(struct gsm_mux *gsm, unsigned int command,
gsm->constipated = false;
gsm_control_reply(gsm, CMD_FCON, NULL, 0);
/* Kick the link in case it is idling */
mutex_lock(&gsm->tx_mutex);
spin_lock_irqsave(&gsm->tx_lock, flags);
gsm_data_kick(gsm, NULL);
mutex_unlock(&gsm->tx_mutex);
spin_unlock_irqrestore(&gsm->tx_lock, flags);
break;
case CMD_FCOFF:
/* Modem wants us to STFU */
@ -2225,7 +2228,6 @@ 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);
@ -2297,12 +2299,12 @@ 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_list);
timer_setup(&gsm->t2_timer, gsm_control_retransmit, 0);
init_waitqueue_head(&gsm->event);
spin_lock_init(&gsm->control_lock);
spin_lock_init(&gsm->tx_lock);
gsm->t1 = T1;
gsm->t2 = T2;
@ -2327,7 +2329,6 @@ 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);
@ -2652,15 +2653,16 @@ 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);
mutex_lock(&gsm->tx_mutex);
spin_lock_irqsave(&gsm->tx_lock, flags);
gsm_data_kick(gsm, NULL);
if (gsm->tx_bytes < TX_THRESH_LO) {
gsm_dlci_data_sweep(gsm);
}
mutex_unlock(&gsm->tx_mutex);
spin_unlock_irqrestore(&gsm->tx_lock, flags);
}
/**
@ -2703,6 +2705,7 @@ 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;
@ -2710,13 +2713,13 @@ 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;
}