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

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This reverts commit 902e02ea93.

The above commit is reverted as the usage of tx_mutex seems not to solve
the problem described in 902e02ea93 ("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 4561d8008a
commit acdab4cb4b
1 changed files with 29 additions and 24 deletions
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53
drivers/tty/n_gsm.c
View file

@ -264,7 +264,7 @@ struct gsm_mux {
bool constipated; /* Asked by remote to shut up */ bool constipated; /* Asked by remote to shut up */
bool has_devices; /* Devices were registered */ bool has_devices; /* Devices were registered */
struct mutex tx_mutex; spinlock_t tx_lock;
unsigned int tx_bytes; /* TX data outstanding */ unsigned int tx_bytes; /* TX data outstanding */
#define TX_THRESH_HI 8192 #define TX_THRESH_HI 8192
#define TX_THRESH_LO 2048 #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; struct gsm_msg *msg;
u8 *dp; u8 *dp;
int ocr; int ocr;
unsigned long flags;
msg = gsm_data_alloc(gsm, addr, 0, control); msg = gsm_data_alloc(gsm, addr, 0, control);
if (!msg) 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); 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); list_add_tail(&msg->list, &gsm->tx_ctrl_list);
gsm->tx_bytes += msg->len; gsm->tx_bytes += msg->len;
mutex_unlock(&gsm->tx_mutex); spin_unlock_irqrestore(&gsm->tx_lock, flags);
gsmld_write_trigger(gsm); gsmld_write_trigger(gsm);
return 0; 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); spin_unlock_irqrestore(&dlci->lock, flags);
/* Clear data packets in MUX write queue */ /* 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) { list_for_each_entry_safe(msg, nmsg, &gsm->tx_data_list, list) {
if (msg->addr != addr) if (msg->addr != addr)
continue; continue;
@ -757,7 +758,7 @@ static void gsm_dlci_clear_queues(struct gsm_mux *gsm, struct gsm_dlci *dlci)
list_del(&msg->list); list_del(&msg->list);
kfree(msg); 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) 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); __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 * 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. * 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) 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 * is data. Keep to the MRU of the mux. This path handles framed data
* queued as skbuffs to the DLCI. * 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, 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) if (dlci->adaption == 4)
overhead = 1; overhead = 1;
/* dlci->skb is locked by tx_mutex */ /* dlci->skb is locked by tx_lock */
if (dlci->skb == NULL) { if (dlci->skb == NULL) {
dlci->skb = skb_dequeue_tail(&dlci->skb_list); dlci->skb = skb_dequeue_tail(&dlci->skb_list);
if (dlci->skb == NULL) 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 * Push an empty frame in to the transmit queue to update the modem status
* bits and to transmit an optional break. * 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, 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) static void gsm_dlci_data_kick(struct gsm_dlci *dlci)
{ {
unsigned long flags;
int sweep; int sweep;
if (dlci->constipated) if (dlci->constipated)
return; 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 */ /* If we have nothing running then we need to fire up */
sweep = (dlci->gsm->tx_bytes < TX_THRESH_LO); sweep = (dlci->gsm->tx_bytes < TX_THRESH_LO);
if (dlci->gsm->tx_bytes == 0) { if (dlci->gsm->tx_bytes == 0) {
@ -1317,7 +1320,7 @@ static void gsm_dlci_data_kick(struct gsm_dlci *dlci)
} }
if (sweep) if (sweep)
gsm_dlci_data_sweep(dlci->gsm); 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) static void gsm_kick_timeout(struct work_struct *work)
{ {
struct gsm_mux *gsm = container_of(work, struct gsm_mux, kick_timeout.work); struct gsm_mux *gsm = container_of(work, struct gsm_mux, kick_timeout.work);
unsigned long flags;
int sent = 0; 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 we have nothing running then we need to fire up */
if (gsm->tx_bytes < TX_THRESH_LO) if (gsm->tx_bytes < TX_THRESH_LO)
sent = gsm_dlci_data_sweep(gsm); sent = gsm_dlci_data_sweep(gsm);
mutex_unlock(&gsm->tx_mutex); spin_unlock_irqrestore(&gsm->tx_lock, flags);
if (sent && debug & DBG_DATA) if (sent && debug & DBG_DATA)
pr_info("%s TX queue stalled\n", __func__); pr_info("%s TX queue stalled\n", __func__);
@ -2565,7 +2569,6 @@ static void gsm_free_mux(struct gsm_mux *gsm)
break; break;
} }
} }
mutex_destroy(&gsm->tx_mutex);
mutex_destroy(&gsm->mutex); mutex_destroy(&gsm->mutex);
kfree(gsm->txframe); kfree(gsm->txframe);
kfree(gsm->buf); kfree(gsm->buf);
@ -2637,7 +2640,6 @@ static struct gsm_mux *gsm_alloc_mux(void)
} }
spin_lock_init(&gsm->lock); spin_lock_init(&gsm->lock);
mutex_init(&gsm->mutex); mutex_init(&gsm->mutex);
mutex_init(&gsm->tx_mutex);
kref_init(&gsm->ref); kref_init(&gsm->ref);
INIT_LIST_HEAD(&gsm->tx_ctrl_list); INIT_LIST_HEAD(&gsm->tx_ctrl_list);
INIT_LIST_HEAD(&gsm->tx_data_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_WORK(&gsm->tx_work, gsmld_write_task);
init_waitqueue_head(&gsm->event); init_waitqueue_head(&gsm->event);
spin_lock_init(&gsm->control_lock); spin_lock_init(&gsm->control_lock);
spin_lock_init(&gsm->tx_lock);
gsm->t1 = T1; gsm->t1 = T1;
gsm->t2 = T2; gsm->t2 = T2;
@ -2670,7 +2673,6 @@ static struct gsm_mux *gsm_alloc_mux(void)
} }
spin_unlock(&gsm_mux_lock); spin_unlock(&gsm_mux_lock);
if (i == MAX_MUX) { if (i == MAX_MUX) {
mutex_destroy(&gsm->tx_mutex);
mutex_destroy(&gsm->mutex); mutex_destroy(&gsm->mutex);
kfree(gsm->txframe); kfree(gsm->txframe);
kfree(gsm->buf); 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) static void gsmld_write_task(struct work_struct *work)
{ {
struct gsm_mux *gsm = container_of(work, struct gsm_mux, tx_work); struct gsm_mux *gsm = container_of(work, struct gsm_mux, tx_work);
unsigned long flags;
int i, ret; int i, ret;
/* All outstanding control channel and control messages and one data /* All outstanding control channel and control messages and one data
* frame is sent. * frame is sent.
*/ */
ret = -ENODEV; ret = -ENODEV;
mutex_lock(&gsm->tx_mutex); spin_lock_irqsave(&gsm->tx_lock, flags);
if (gsm->tty) if (gsm->tty)
ret = gsm_data_kick(gsm); ret = gsm_data_kick(gsm);
mutex_unlock(&gsm->tx_mutex); spin_unlock_irqrestore(&gsm->tx_lock, flags);
if (ret >= 0) if (ret >= 0)
for (i = 0; i < NUM_DLCI; i++) 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) const unsigned char *buf, size_t nr)
{ {
struct gsm_mux *gsm = tty->disc_data; struct gsm_mux *gsm = tty->disc_data;
unsigned long flags;
int space; int space;
int ret; int ret;
@ -3049,13 +3053,13 @@ static ssize_t gsmld_write(struct tty_struct *tty, struct file *file,
return -ENODEV; return -ENODEV;
ret = -ENOBUFS; ret = -ENOBUFS;
mutex_lock(&gsm->tx_mutex); spin_lock_irqsave(&gsm->tx_lock, flags);
space = tty_write_room(tty); space = tty_write_room(tty);
if (space >= nr) if (space >= nr)
ret = tty->ops->write(tty, buf, nr); ret = tty->ops->write(tty, buf, nr);
else else
set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags); set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
mutex_unlock(&gsm->tx_mutex); spin_unlock_irqrestore(&gsm->tx_lock, flags);
return ret; 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) static void gsm_modem_upd_via_data(struct gsm_dlci *dlci, u8 brk)
{ {
struct gsm_mux *gsm = dlci->gsm; struct gsm_mux *gsm = dlci->gsm;
unsigned long flags;
if (dlci->state != DLCI_OPEN || dlci->adaption != 2) if (dlci->state != DLCI_OPEN || dlci->adaption != 2)
return; return;
mutex_lock(&gsm->tx_mutex); spin_lock_irqsave(&gsm->tx_lock, flags);
gsm_dlci_modem_output(gsm, dlci, brk); gsm_dlci_modem_output(gsm, dlci, brk);
mutex_unlock(&gsm->tx_mutex); spin_unlock_irqrestore(&gsm->tx_lock, flags);
} }
/** /**