From: Fedor Pchelkin pchelkin@ispras.ru
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 --- drivers/tty/n_gsm.c | 39 +++++++++++++++++++++------------------ 1 file changed, 21 insertions(+), 18 deletions(-)
--- 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_ * * 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_dl * 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 g * 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(s 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 g
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 gs } 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 g 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 g 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 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(voi } 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(voi } 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 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_st 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_st 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; }