From: Fedor Pchelkin pchelkin@ispras.ru

[ Upstream commit 15743ae50e04aa907131e3ae8d66e9a2964ea232 ]

This reverts commit 2af54fe4f713d5f29e1520d7780112ff9b6121be.

The above commit is reverted as it was a prerequisite for tx_mutex introduction and tx_mutex has been removed as it does not correctly work in order to protect tx data.

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/20221008110221.13645-3-pchelkin@ispras.ru Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/tty/n_gsm.c | 16 ++++++++-------- 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/drivers/tty/n_gsm.c b/drivers/tty/n_gsm.c index e23225aff5d9..d6598ca3640f 100644 --- a/drivers/tty/n_gsm.c +++ b/drivers/tty/n_gsm.c @@ -256,7 +256,7 @@ struct gsm_mux { struct list_head tx_data_list; /* Pending data packets */

/* Control messages */ - struct delayed_work kick_timeout; /* Kick TX queuing on timeout */ + struct timer_list kick_timer; /* Kick TX queuing on timeout */ struct timer_list t2_timer; /* Retransmit timer for commands */ int cretries; /* Command retry counter */ struct gsm_control *pending_cmd;/* Our current pending command */ @@ -1009,7 +1009,7 @@ static void __gsm_data_queue(struct gsm_dlci *dlci, struct gsm_msg *msg) gsm->tx_bytes += msg->len;

gsmld_write_trigger(gsm); - schedule_delayed_work(&gsm->kick_timeout, 10 * gsm->t1 * HZ / 100); + mod_timer(&gsm->kick_timer, jiffies + 10 * gsm->t1 * HZ / 100); }

/** @@ -1984,16 +1984,16 @@ static void gsm_dlci_command(struct gsm_dlci *dlci, const u8 *data, int len) }

/** - * gsm_kick_timeout - transmit if possible - * @work: work contained in our gsm object + * gsm_kick_timer - transmit if possible + * @t: timer contained in our gsm object * * Transmit data from DLCIs if the queue is empty. We can't rely on * a tty wakeup except when we filled the pipe so we need to fire off * new data ourselves in other cases. */ -static void gsm_kick_timeout(struct work_struct *work) +static void gsm_kick_timer(struct timer_list *t) { - struct gsm_mux *gsm = container_of(work, struct gsm_mux, kick_timeout.work); + struct gsm_mux *gsm = from_timer(gsm, t, kick_timer); unsigned long flags; int sent = 0;

@@ -2458,7 +2458,7 @@ static void gsm_cleanup_mux(struct gsm_mux *gsm, bool disc) }

/* Finish outstanding timers, making sure they are done */ - cancel_delayed_work_sync(&gsm->kick_timeout); + del_timer_sync(&gsm->kick_timer); del_timer_sync(&gsm->t2_timer);

/* Finish writing to ldisc */ @@ -2605,7 +2605,7 @@ static struct gsm_mux *gsm_alloc_mux(void) kref_init(&gsm->ref); INIT_LIST_HEAD(&gsm->tx_ctrl_list); INIT_LIST_HEAD(&gsm->tx_data_list); - INIT_DELAYED_WORK(&gsm->kick_timeout, gsm_kick_timeout); + timer_setup(&gsm->kick_timer, gsm_kick_timer, 0); timer_setup(&gsm->t2_timer, gsm_control_retransmit, 0); INIT_WORK(&gsm->tx_work, gsmld_write_task); init_waitqueue_head(&gsm->event);

From: Fedor Pchelkin pchelkin@ispras.ru

[ Upstream commit acdab4cb4ba7e5f94d2b422ebd7bf4bf68178fb2 ]

This reverts commit eb75efdec8dd0f01ac85c88feafa6e63b34a2521.

The above commit is reverted as the usage of tx_mutex seems not to solve the problem described in eb75efdec8dd ("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 Reviewed-by: Pavel Machek pavel@denx.de --- v1->v2: added signed-off-by and reviewed-by

drivers/tty/n_gsm.c | 39 +++++++++++++++++++++------------------ 1 file changed, 21 insertions(+), 18 deletions(-)

diff --git a/drivers/tty/n_gsm.c b/drivers/tty/n_gsm.c index c91a3004931f..c2212f52a603 100644 --- a/drivers/tty/n_gsm.c +++ b/drivers/tty/n_gsm.c @@ -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; }