From: Daniel Starke <[email protected]>
After setting up the control channel on both sides the responder side may
want to open a virtual tty to listen on until the initiator starts an
application on a user channel. The current implementation allows the
open() but no other operation, like termios. These fail with EINVAL.
The responder sided application has no means to detect an open by the
initiator sided application this way. And the initiator sided applications
usually expect the responder sided application to listen on the user
channel upon open.
Set the user channel into half-open state on responder side once a user
application opens the virtual tty to allow IO operations on it.
Furthermore, keep the user channel constipated until the initiator side
opens it to give the responder sided application the chance to detect the
new connection and to avoid data loss if the responder sided application
starts sending before the user channel is open.
Fixes: e1eaea46bb40 ("tty: n_gsm line discipline")
Cc: [email protected]
Signed-off-by: Daniel Starke <[email protected]>
---
drivers/tty/n_gsm.c | 31 +++++++++++++++++++++++++++++--
1 file changed, 29 insertions(+), 2 deletions(-)
Renamed gsm_dlci_wait_open() to gsm_dlci_set_opening() and reworded its
documentation accordingly to reflect its function. This was done due to the
review comment on v2.
Link: https://lore.kernel.org/all/[email protected]/
Link: https://lore.kernel.org/all/[email protected]/
diff --git a/drivers/tty/n_gsm.c b/drivers/tty/n_gsm.c
index fd8b86dde525..63314fe5e43b 100644
--- a/drivers/tty/n_gsm.c
+++ b/drivers/tty/n_gsm.c
@@ -1493,6 +1493,8 @@ static void gsm_dlci_close(struct gsm_dlci *dlci)
if (debug & 8)
pr_debug("DLCI %d goes closed.\n", dlci->addr);
dlci->state = DLCI_CLOSED;
+ /* Prevent us from sending data before the link is up again */
+ dlci->constipated = true;
if (dlci->addr != 0) {
tty_port_tty_hangup(&dlci->port, false);
spin_lock_irqsave(&dlci->lock, flags);
@@ -1522,6 +1524,7 @@ static void gsm_dlci_open(struct gsm_dlci *dlci)
del_timer(&dlci->t1);
/* This will let a tty open continue */
dlci->state = DLCI_OPEN;
+ dlci->constipated = false;
if (debug & 8)
pr_debug("DLCI %d goes open.\n", dlci->addr);
/* Send current modem state */
@@ -1602,6 +1605,25 @@ static void gsm_dlci_begin_open(struct gsm_dlci *dlci)
mod_timer(&dlci->t1, jiffies + gsm->t1 * HZ / 100);
}
+/**
+ * gsm_dlci_set_opening - change state to opening
+ * @dlci: DLCI to open
+ *
+ * Change internal state to wait for DLCI open from initiator side.
+ * We set off timers and responses upon reception of an SABM.
+ */
+static void gsm_dlci_set_opening(struct gsm_dlci *dlci)
+{
+ switch (dlci->state) {
+ case DLCI_CLOSED:
+ case DLCI_CLOSING:
+ dlci->state = DLCI_OPENING;
+ break;
+ default:
+ break;
+ }
+}
+
/**
* gsm_dlci_begin_close - start channel open procedure
* @dlci: DLCI to open
@@ -1745,10 +1767,13 @@ static struct gsm_dlci *gsm_dlci_alloc(struct gsm_mux *gsm, int addr)
dlci->addr = addr;
dlci->adaption = gsm->adaption;
dlci->state = DLCI_CLOSED;
- if (addr)
+ if (addr) {
dlci->data = gsm_dlci_data;
- else
+ /* Prevent us from sending data before the link is up */
+ dlci->constipated = true;
+ } else {
dlci->data = gsm_dlci_command;
+ }
gsm->dlci[addr] = dlci;
return dlci;
}
@@ -3163,6 +3188,8 @@ static int gsmtty_open(struct tty_struct *tty, struct file *filp)
/* Start sending off SABM messages */
if (gsm->initiator)
gsm_dlci_begin_open(dlci);
+ else
+ gsm_dlci_set_opening(dlci);
/* And wait for virtual carrier */
return tty_port_block_til_ready(port, tty, filp);
}
--
2.34.1
From: Daniel Starke <[email protected]>
1) The function drains the fifo for the given user tty/DLCI without
considering 'TX_THRESH_HI' and different to gsm_dlci_data_output_framed(),
which moves only one packet from the user side to the internal transmission
queue. We can only handle one packet at a time here if we want to allow
DLCI priority handling in gsm_dlci_data_sweep() to avoid link starvation.
2) Furthermore, the additional header octet from convergence layer type 2
is not counted against MTU. It is part of the UI/UIH frame message which
needs to be limited to MTU. Hence, it is wrong not to consider this octet.
3) Finally, the waiting user tty is not informed about freed space in its
send queue.
Take at most one packet worth of data out of the DLCI fifo to fix 1).
Limit the max user data size per packet to MTU - 1 in case of convergence
layer type 2 to leave space for the control signal octet which is added in
the later part of the function. This fixes 2).
Add tty_port_tty_wakeup() to wake up the user tty if new write space has
been made available to fix 3).
Fixes: 268e526b935e ("tty/n_gsm: avoid fifo overflow in gsm_dlci_data_output")
Cc: [email protected]
Signed-off-by: Daniel Starke <[email protected]>
---
drivers/tty/n_gsm.c | 74 +++++++++++++++++++++++++--------------------
1 file changed, 42 insertions(+), 32 deletions(-)
There have been no comments on v2, hence, no change was done.
Link: https://lore.kernel.org/all/[email protected]/
diff --git a/drivers/tty/n_gsm.c b/drivers/tty/n_gsm.c
index 9b0bbd0d35d0..b51e2023d88d 100644
--- a/drivers/tty/n_gsm.c
+++ b/drivers/tty/n_gsm.c
@@ -869,41 +869,51 @@ static int gsm_dlci_data_output(struct gsm_mux *gsm, struct gsm_dlci *dlci)
{
struct gsm_msg *msg;
u8 *dp;
- int len, total_size, size;
- int h = dlci->adaption - 1;
+ int h, len, size;
- total_size = 0;
- while (1) {
- len = kfifo_len(&dlci->fifo);
- if (len == 0)
- return total_size;
-
- /* MTU/MRU count only the data bits */
- if (len > gsm->mtu)
- len = gsm->mtu;
-
- size = len + h;
-
- msg = gsm_data_alloc(gsm, dlci->addr, size, gsm->ftype);
- /* FIXME: need a timer or something to kick this so it can't
- get stuck with no work outstanding and no buffer free */
- if (msg == NULL)
- return -ENOMEM;
- dp = msg->data;
- switch (dlci->adaption) {
- case 1: /* Unstructured */
- break;
- case 2: /* Unstructed with modem bits.
- Always one byte as we never send inline break data */
- *dp++ = (gsm_encode_modem(dlci) << 1) | EA;
- break;
- }
- WARN_ON(kfifo_out_locked(&dlci->fifo, dp , len, &dlci->lock) != len);
- __gsm_data_queue(dlci, msg);
- total_size += size;
+ /* for modem bits without break data */
+ h = ((dlci->adaption == 1) ? 0 : 1);
+
+ len = kfifo_len(&dlci->fifo);
+ if (len == 0)
+ return 0;
+
+ /* MTU/MRU count only the data bits but watch adaption mode */
+ if ((len + h) > gsm->mtu)
+ len = gsm->mtu - h;
+
+ size = len + h;
+
+ msg = gsm_data_alloc(gsm, dlci->addr, size, gsm->ftype);
+ /* FIXME: need a timer or something to kick this so it can't
+ * get stuck with no work outstanding and no buffer free
+ */
+ if (!msg)
+ return -ENOMEM;
+ dp = msg->data;
+ switch (dlci->adaption) {
+ case 1: /* Unstructured */
+ break;
+ case 2: /* Unstructured with modem bits.
+ * Always one byte as we never send inline break data
+ */
+ *dp++ = (gsm_encode_modem(dlci) << 1) | EA;
+ break;
+ default:
+ pr_err("%s: unsupported adaption %d\n", __func__,
+ dlci->adaption);
+ break;
}
+
+ WARN_ON(len != kfifo_out_locked(&dlci->fifo, dp, len,
+ &dlci->lock));
+
+ /* Notify upper layer about available send space. */
+ tty_port_tty_wakeup(&dlci->port);
+
+ __gsm_data_queue(dlci, msg);
/* Bytes of data we used up */
- return total_size;
+ return size;
}
/**
--
2.34.1
From: Daniel Starke <[email protected]>
In the current implementation control packets are re-transmitted even if
the control channel closed down during T2. This is wrong.
Check whether the control channel is open before re-transmitting any
packets. Note that control channel open/close is handled by T1 and not T2
and remains unaffected by this.
Fixes: e1eaea46bb40 ("tty: n_gsm line discipline")
Cc: [email protected]
Signed-off-by: Daniel Starke <[email protected]>
---
drivers/tty/n_gsm.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
There have been no comments on v2, hence, no change was done.
Link: https://lore.kernel.org/all/[email protected]/
diff --git a/drivers/tty/n_gsm.c b/drivers/tty/n_gsm.c
index b82efb63f4e6..9e4ada510c9f 100644
--- a/drivers/tty/n_gsm.c
+++ b/drivers/tty/n_gsm.c
@@ -1624,7 +1624,7 @@ static void gsm_control_retransmit(struct timer_list *t)
spin_lock_irqsave(&gsm->control_lock, flags);
ctrl = gsm->pending_cmd;
if (ctrl) {
- if (gsm->cretries == 0) {
+ if (gsm->cretries == 0 || !gsm->dlci[0] || gsm->dlci[0]->dead) {
gsm->pending_cmd = NULL;
ctrl->error = -ETIMEDOUT;
ctrl->done = 1;
--
2.34.1
From: Daniel Starke <[email protected]>
Within gsm_activate_mux() all timers and locks are initiated before the
actual resource for the control channel is allocated. This can lead to race
conditions.
Allocate the control channel DLCI object first to avoid race conditions.
Fixes: e1eaea46bb40 ("tty: n_gsm line discipline")
Cc: [email protected]
Signed-off-by: Daniel Starke <[email protected]>
---
drivers/tty/n_gsm.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
There have been no comments on v2, hence, no change was done.
Link: https://lore.kernel.org/all/[email protected]/
diff --git a/drivers/tty/n_gsm.c b/drivers/tty/n_gsm.c
index 9e4ada510c9f..b0b093e8e9d9 100644
--- a/drivers/tty/n_gsm.c
+++ b/drivers/tty/n_gsm.c
@@ -2483,6 +2483,10 @@ static int gsm_activate_mux(struct gsm_mux *gsm)
struct gsm_dlci *dlci;
int ret;
+ dlci = gsm_dlci_alloc(gsm, 0);
+ if (dlci == NULL)
+ return -ENOMEM;
+
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);
@@ -2499,9 +2503,6 @@ static int gsm_activate_mux(struct gsm_mux *gsm)
if (ret)
return ret;
- dlci = gsm_dlci_alloc(gsm, 0);
- if (dlci == NULL)
- return -ENOMEM;
gsm->has_devices = true;
gsm->dead = false; /* Tty opens are now permissible */
return 0;
--
2.34.1
From: Daniel Starke <[email protected]>
The current implementation queues up new control and user packets as needed
and processes this queue down to the ldisc in the same code path.
That means that the upper and the lower layer are hard coupled in the code.
Due to this deadlocks can happen as seen below while transmitting data,
especially during ldisc congestion. Furthermore, the data channels starve
the control channel on high transmission load on the ldisc.
Introduce an additional control channel data queue to prevent timeouts and
link hangups during ldisc congestion. This is being processed before the
user channel data queue in gsm_data_kick(), i.e. with the highest priority.
Put the queue to ldisc data path into a workqueue and trigger it whenever
new data has been put into the transmission queue. Change
gsm_dlci_data_sweep() accordingly to fill up the transmission queue until
TX_THRESH_HI. This solves the locking issue, keeps latency low and provides
good performance on high data load.
Note that now all packets from a DLCI are removed from the internal queue
if the associated DLCI was closed. This ensures that no data is sent by the
introduced write task to an already closed DLCI.
BUG: spinlock recursion on CPU#0, test_v24_loop/124
lock: serial8250_ports+0x3a8/0x7500, .magic: dead4ead, .owner: test_v24_loop/124, .owner_cpu: 0
CPU: 0 PID: 124 Comm: test_v24_loop Tainted: G O 5.18.0-rc2 #3
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/2014
Call Trace:
<IRQ>
dump_stack_lvl+0x34/0x44
do_raw_spin_lock+0x76/0xa0
_raw_spin_lock_irqsave+0x72/0x80
uart_write_room+0x3b/0xc0
gsm_data_kick+0x14b/0x240 [n_gsm]
gsmld_write_wakeup+0x35/0x70 [n_gsm]
tty_wakeup+0x53/0x60
tty_port_default_wakeup+0x1b/0x30
serial8250_tx_chars+0x12f/0x220
serial8250_handle_irq.part.0+0xfe/0x150
serial8250_default_handle_irq+0x48/0x80
serial8250_interrupt+0x56/0xa0
__handle_irq_event_percpu+0x78/0x1f0
handle_irq_event+0x34/0x70
handle_fasteoi_irq+0x90/0x1e0
__common_interrupt+0x69/0x100
common_interrupt+0x48/0xc0
asm_common_interrupt+0x1e/0x40
RIP: 0010:__do_softirq+0x83/0x34e
Code: 2a 0a ff 0f b7 ed c7 44 24 10 0a 00 00 00 48 c7 c7 51 2a 64 82 e8 2d
e2 d5 ff 65 66 c7 05 83 af 1e 7e 00 00 fb b8 ff ff ff ff <49> c7 c2 40 61
80 82 0f bc c5 41 89 c4 41 83 c4 01 0f 84 e6 00 00
RSP: 0018:ffffc90000003f98 EFLAGS: 00000286
RAX: 00000000ffffffff RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff82642a51 RDI: ffffffff825bb5e7
RBP: 0000000000000200 R08: 00000008de3271a8 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000030 R14: 0000000000000000 R15: 0000000000000000
? __do_softirq+0x73/0x34e
irq_exit_rcu+0xb5/0x100
common_interrupt+0xa4/0xc0
</IRQ>
<TASK>
asm_common_interrupt+0x1e/0x40
RIP: 0010:_raw_spin_unlock_irqrestore+0x2e/0x50
Code: 00 55 48 89 fd 48 83 c7 18 53 48 89 f3 48 8b 74 24 10 e8 85 28 36 ff
48 89 ef e8 cd 58 36 ff 80 e7 02 74 01 fb bf 01 00 00 00 <e8> 3d 97 33 ff
65 8b 05 96 23 2b 7e 85 c0 74 03 5b 5d c3 0f 1f 44
RSP: 0018:ffffc9000020fd08 EFLAGS: 00000202
RAX: 0000000000000000 RBX: 0000000000000246 RCX: 0000000000000000
RDX: 0000000000000004 RSI: ffffffff8257fd74 RDI: 0000000000000001
RBP: ffff8880057de3a0 R08: 00000008de233000 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000100 R14: 0000000000000202 R15: ffff8880057df0b8
? _raw_spin_unlock_irqrestore+0x23/0x50
gsmtty_write+0x65/0x80 [n_gsm]
n_tty_write+0x33f/0x530
? swake_up_all+0xe0/0xe0
file_tty_write.constprop.0+0x1b1/0x320
? n_tty_flush_buffer+0xb0/0xb0
new_sync_write+0x10c/0x190
vfs_write+0x282/0x310
ksys_write+0x68/0xe0
do_syscall_64+0x3b/0x90
entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x7f3e5e35c15c
Code: 8b 7c 24 08 89 c5 e8 c5 ff ff ff 89 ef 89 44 24 08 e8 58 bc 02 00 8b
44 24 08 48 83 c4 10 5d c3 48 63 ff b8 01 00 00 00 0f 05 <48> 3d 00 f0 ff
ff 76 10 48 8b 15 fd fc 05 00 f7 d8 64 89 02 48 83
RSP: 002b:00007ffcee77cd18 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007ffcee77cd70 RCX: 00007f3e5e35c15c
RDX: 0000000000000100 RSI: 00007ffcee77cd90 RDI: 0000000000000003
RBP: 0000000000000100 R08: 0000000000000000 R09: 7efefefefefefeff
R10: 00007f3e5e3bddeb R11: 0000000000000246 R12: 00007ffcee77ce8f
R13: 0000000000000001 R14: 000056214404e010 R15: 00007ffcee77cd90
</TASK>
Fixes: e1eaea46bb40 ("tty: n_gsm line discipline")
Cc: [email protected]
Signed-off-by: Daniel Starke <[email protected]>
---
drivers/tty/n_gsm.c | 410 ++++++++++++++++++++++++++++++--------------
1 file changed, 280 insertions(+), 130 deletions(-)
There have been no comments on v2, hence, no change was done.
Link: https://lore.kernel.org/all/[email protected]/
diff --git a/drivers/tty/n_gsm.c b/drivers/tty/n_gsm.c
index 1a6701ae11e7..b82efb63f4e6 100644
--- a/drivers/tty/n_gsm.c
+++ b/drivers/tty/n_gsm.c
@@ -5,6 +5,14 @@
*
* * THIS IS A DEVELOPMENT SNAPSHOT IT IS NOT A FINAL RELEASE *
*
+ * Outgoing path:
+ * tty -> DLCI fifo -> scheduler -> GSM MUX data queue ---o-> ldisc
+ * control message -> GSM MUX control queue --ยด
+ *
+ * Incoming path:
+ * ldisc -> gsm_queue() -o--> tty
+ * `-> gsm_control_response()
+ *
* TO DO:
* Mostly done: ioctls for setting modes/timing
* Partly done: hooks so you can pull off frames to non tty devs
@@ -210,6 +218,9 @@ struct gsm_mux {
/* Events on the GSM channel */
wait_queue_head_t event;
+ /* ldisc send work */
+ struct work_struct tx_work;
+
/* Bits for GSM mode decoding */
/* Framing Layer */
@@ -241,7 +252,8 @@ struct gsm_mux {
unsigned int tx_bytes; /* TX data outstanding */
#define TX_THRESH_HI 8192
#define TX_THRESH_LO 2048
- struct list_head tx_list; /* Pending data packets */
+ struct list_head tx_ctrl_list; /* Pending control packets */
+ struct list_head tx_data_list; /* Pending data packets */
/* Control messages */
struct timer_list kick_timer; /* Kick TX queuing on timeout */
@@ -371,6 +383,11 @@ static const u8 gsm_fcs8[256] = {
static int gsmld_output(struct gsm_mux *gsm, u8 *data, int len);
static int gsm_modem_update(struct gsm_dlci *dlci, u8 brk);
+static struct gsm_msg *gsm_data_alloc(struct gsm_mux *gsm, u8 addr, int len,
+ u8 ctrl);
+static int gsm_send_packet(struct gsm_mux *gsm, struct gsm_msg *msg);
+static void gsmld_write_trigger(struct gsm_mux *gsm);
+static void gsmld_write_task(struct work_struct *work);
/**
* gsm_fcs_add - update FCS
@@ -636,57 +653,73 @@ static int gsm_stuff_frame(const u8 *input, u8 *output, int len)
* @cr: command/response bit seen as initiator
* @control: control byte including PF bit
*
- * Format up and transmit a control frame. These do not go via the
- * queueing logic as they should be transmitted ahead of data when
- * they are needed.
- *
- * FIXME: Lock versus data TX path
+ * Format up and transmit a control frame. These should be transmitted
+ * ahead of data when they are needed.
*/
-
-static void gsm_send(struct gsm_mux *gsm, int addr, int cr, int control)
+static int gsm_send(struct gsm_mux *gsm, int addr, int cr, int control)
{
- int len;
- u8 cbuf[10];
- u8 ibuf[3];
+ struct gsm_msg *msg;
+ u8 *dp;
int ocr;
+ unsigned long flags;
+
+ msg = gsm_data_alloc(gsm, addr, 0, control);
+ if (!msg)
+ return -ENOMEM;
/* toggle C/R coding if not initiator */
ocr = cr ^ (gsm->initiator ? 0 : 1);
- switch (gsm->encoding) {
- case 0:
- cbuf[0] = GSM0_SOF;
- cbuf[1] = (addr << 2) | (ocr << 1) | EA;
- cbuf[2] = control;
- cbuf[3] = EA; /* Length of data = 0 */
- cbuf[4] = 0xFF - gsm_fcs_add_block(INIT_FCS, cbuf + 1, 3);
- cbuf[5] = GSM0_SOF;
- len = 6;
- break;
- case 1:
- case 2:
- /* Control frame + packing (but not frame stuffing) in mode 1 */
- ibuf[0] = (addr << 2) | (ocr << 1) | EA;
- ibuf[1] = control;
- ibuf[2] = 0xFF - gsm_fcs_add_block(INIT_FCS, ibuf, 2);
- /* Stuffing may double the size worst case */
- len = gsm_stuff_frame(ibuf, cbuf + 1, 3);
- /* Now add the SOF markers */
- cbuf[0] = GSM1_SOF;
- cbuf[len + 1] = GSM1_SOF;
- /* FIXME: we can omit the lead one in many cases */
- len += 2;
- break;
- default:
- WARN_ON(1);
- return;
- }
- gsmld_output(gsm, cbuf, len);
- if (!gsm->initiator) {
- cr = cr & gsm->initiator;
- control = control & ~PF;
+ msg->data -= 3;
+ dp = msg->data;
+ *dp++ = (addr << 2) | (ocr << 1) | EA;
+ *dp++ = control;
+
+ if (gsm->encoding == 0)
+ *dp++ = EA; /* Length of data = 0 */
+
+ *dp = 0xFF - gsm_fcs_add_block(INIT_FCS, msg->data, dp - msg->data);
+ msg->len = (dp - msg->data) + 1;
+
+ gsm_print_packet("Q->", addr, cr, control, NULL, 0);
+
+ spin_lock_irqsave(&gsm->tx_lock, flags);
+ list_add_tail(&msg->list, &gsm->tx_ctrl_list);
+ gsm->tx_bytes += msg->len;
+ spin_unlock_irqrestore(&gsm->tx_lock, flags);
+ gsmld_write_trigger(gsm);
+
+ return 0;
+}
+
+/**
+ * gsm_dlci_clear_queues - remove outstanding data for a DLCI
+ * @gsm: mux
+ * @dlci: clear for this DLCI
+ *
+ * Clears the data queues for a given DLCI.
+ */
+static void gsm_dlci_clear_queues(struct gsm_mux *gsm, struct gsm_dlci *dlci)
+{
+ struct gsm_msg *msg, *nmsg;
+ int addr = dlci->addr;
+ unsigned long flags;
+
+ /* Clear DLCI write fifo first */
+ spin_lock_irqsave(&dlci->lock, flags);
+ kfifo_reset(&dlci->fifo);
+ spin_unlock_irqrestore(&dlci->lock, flags);
+
+ /* Clear data packets in MUX write queue */
+ spin_lock_irqsave(&gsm->tx_lock, flags);
+ list_for_each_entry_safe(msg, nmsg, &gsm->tx_data_list, list) {
+ if (msg->addr != addr)
+ continue;
+ gsm->tx_bytes -= msg->len;
+ list_del(&msg->list);
+ kfree(msg);
}
- gsm_print_packet("-->", addr, cr, control, NULL, 0);
+ spin_unlock_irqrestore(&gsm->tx_lock, flags);
}
/**
@@ -748,6 +781,46 @@ static struct gsm_msg *gsm_data_alloc(struct gsm_mux *gsm, u8 addr, int len,
return m;
}
+/**
+ * gsm_send_packet - sends a single packet
+ * @gsm: GSM Mux
+ * @msg: packet to send
+ *
+ * The given packet is encoded and sent out. No memory is freed.
+ * The caller must hold the gsm tx lock.
+ */
+static int gsm_send_packet(struct gsm_mux *gsm, struct gsm_msg *msg)
+{
+ int len, ret;
+
+
+ if (gsm->encoding == 0) {
+ gsm->txframe[0] = GSM0_SOF;
+ memcpy(gsm->txframe + 1, msg->data, msg->len);
+ gsm->txframe[msg->len + 1] = GSM0_SOF;
+ len = msg->len + 2;
+ } else {
+ gsm->txframe[0] = GSM1_SOF;
+ len = gsm_stuff_frame(msg->data, gsm->txframe + 1, msg->len);
+ gsm->txframe[len + 1] = GSM1_SOF;
+ len += 2;
+ }
+
+ if (debug & 4)
+ print_hex_dump_bytes("gsm_send_packet: ", DUMP_PREFIX_OFFSET,
+ gsm->txframe, len);
+ gsm_print_packet("-->", msg->addr, gsm->initiator, msg->ctrl, msg->data,
+ msg->len);
+
+ ret = gsmld_output(gsm, gsm->txframe, len);
+ if (ret <= 0)
+ return ret;
+ /* FIXME: Can eliminate one SOF in many more cases */
+ gsm->tx_bytes -= msg->len;
+
+ return 0;
+}
+
/**
* gsm_is_flow_ctrl_msg - checks if flow control message
* @msg: message to check
@@ -780,61 +853,81 @@ static bool gsm_is_flow_ctrl_msg(struct gsm_msg *msg)
}
/**
- * gsm_data_kick - poke the queue
+ * gsm_data_kick - poke the queue
* @gsm: GSM Mux
- * @dlci: DLCI sending the data
*
* The tty device has called us to indicate that room has appeared in
- * the transmit queue. Ram more data into the pipe if we have any
+ * the transmit queue. Ram more data into the pipe if we have any.
* If we have been flow-stopped by a CMD_FCOFF, then we can only
- * send messages on DLCI0 until CMD_FCON
- *
- * FIXME: lock against link layer control transmissions
+ * send messages on DLCI0 until CMD_FCON. The caller must hold
+ * the gsm tx lock.
*/
-
-static void gsm_data_kick(struct gsm_mux *gsm, struct gsm_dlci *dlci)
+static int gsm_data_kick(struct gsm_mux *gsm)
{
struct gsm_msg *msg, *nmsg;
- int len;
+ struct gsm_dlci *dlci;
+ int ret;
- list_for_each_entry_safe(msg, nmsg, &gsm->tx_list, list) {
+ clear_bit(TTY_DO_WRITE_WAKEUP, &gsm->tty->flags);
+
+ /* Serialize control messages and control channel messages first */
+ list_for_each_entry_safe(msg, nmsg, &gsm->tx_ctrl_list, list) {
if (gsm->constipated && !gsm_is_flow_ctrl_msg(msg))
+ return -EAGAIN;
+ ret = gsm_send_packet(gsm, msg);
+ switch (ret) {
+ case -ENOSPC:
+ return -ENOSPC;
+ case -ENODEV:
+ /* ldisc not open */
+ gsm->tx_bytes -= msg->len;
+ list_del(&msg->list);
+ kfree(msg);
continue;
- if (gsm->encoding != 0) {
- gsm->txframe[0] = GSM1_SOF;
- len = gsm_stuff_frame(msg->data,
- gsm->txframe + 1, msg->len);
- gsm->txframe[len + 1] = GSM1_SOF;
- len += 2;
- } else {
- gsm->txframe[0] = GSM0_SOF;
- memcpy(gsm->txframe + 1 , msg->data, msg->len);
- gsm->txframe[msg->len + 1] = GSM0_SOF;
- len = msg->len + 2;
- }
-
- if (debug & 4)
- print_hex_dump_bytes("gsm_data_kick: ",
- DUMP_PREFIX_OFFSET,
- gsm->txframe, len);
- if (gsmld_output(gsm, gsm->txframe, len) <= 0)
+ default:
+ if (ret >= 0) {
+ list_del(&msg->list);
+ kfree(msg);
+ }
break;
- /* FIXME: Can eliminate one SOF in many more cases */
- gsm->tx_bytes -= msg->len;
-
- list_del(&msg->list);
- kfree(msg);
+ }
+ }
- if (dlci) {
- tty_port_tty_wakeup(&dlci->port);
- } else {
- int i = 0;
+ if (gsm->constipated)
+ return -EAGAIN;
- for (i = 0; i < NUM_DLCI; i++)
- if (gsm->dlci[i])
- tty_port_tty_wakeup(&gsm->dlci[i]->port);
+ /* Serialize other channels */
+ if (list_empty(&gsm->tx_data_list))
+ return 0;
+ list_for_each_entry_safe(msg, nmsg, &gsm->tx_data_list, list) {
+ dlci = gsm->dlci[msg->addr];
+ /* Send only messages for DLCIs with valid state */
+ if (dlci->state != DLCI_OPEN) {
+ gsm->tx_bytes -= msg->len;
+ list_del(&msg->list);
+ kfree(msg);
+ continue;
+ }
+ ret = gsm_send_packet(gsm, msg);
+ switch (ret) {
+ case -ENOSPC:
+ return -ENOSPC;
+ case -ENODEV:
+ /* ldisc not open */
+ gsm->tx_bytes -= msg->len;
+ list_del(&msg->list);
+ kfree(msg);
+ continue;
+ default:
+ if (ret >= 0) {
+ list_del(&msg->list);
+ kfree(msg);
+ }
+ break;
}
}
+
+ return 1;
}
/**
@@ -883,9 +976,21 @@ static void __gsm_data_queue(struct gsm_dlci *dlci, struct gsm_msg *msg)
msg->data = dp;
/* Add to the actual output queue */
- list_add_tail(&msg->list, &gsm->tx_list);
+ switch (msg->ctrl & ~PF) {
+ case UI:
+ case UIH:
+ if (msg->addr > 0) {
+ list_add_tail(&msg->list, &gsm->tx_data_list);
+ break;
+ }
+ fallthrough;
+ default:
+ list_add_tail(&msg->list, &gsm->tx_ctrl_list);
+ break;
+ }
gsm->tx_bytes += msg->len;
- gsm_data_kick(gsm, dlci);
+
+ gsmld_write_trigger(gsm);
mod_timer(&gsm->kick_timer, jiffies + 10 * gsm->t1 * HZ / 100);
}
@@ -1112,32 +1217,39 @@ static int gsm_dlci_modem_output(struct gsm_mux *gsm, struct gsm_dlci *dlci,
static int gsm_dlci_data_sweep(struct gsm_mux *gsm)
{
- int len, ret = 0;
/* Priority ordering: We should do priority with RR of the groups */
- int i = 1;
-
- while (i < NUM_DLCI) {
- struct gsm_dlci *dlci;
+ int i, len, ret = 0;
+ bool sent;
+ struct gsm_dlci *dlci;
- if (gsm->tx_bytes > TX_THRESH_HI)
- break;
- dlci = gsm->dlci[i];
- if (dlci == NULL || dlci->constipated) {
- i++;
- continue;
+ while (gsm->tx_bytes < TX_THRESH_HI) {
+ for (sent = false, i = 1; i < NUM_DLCI; i++) {
+ dlci = gsm->dlci[i];
+ /* skip unused or blocked channel */
+ if (!dlci || dlci->constipated)
+ continue;
+ /* skip channels with invalid state */
+ if (dlci->state != DLCI_OPEN)
+ continue;
+ /* count the sent data per adaption */
+ if (dlci->adaption < 3 && !dlci->net)
+ len = gsm_dlci_data_output(gsm, dlci);
+ else
+ len = gsm_dlci_data_output_framed(gsm, dlci);
+ /* on error exit */
+ if (len < 0)
+ return ret;
+ if (len > 0) {
+ ret++;
+ sent = true;
+ /* The lower DLCs can starve the higher DLCs! */
+ break;
+ }
+ /* try next */
}
- if (dlci->adaption < 3 && !dlci->net)
- len = gsm_dlci_data_output(gsm, dlci);
- else
- len = gsm_dlci_data_output_framed(gsm, dlci);
- if (len < 0)
+ if (!sent)
break;
- /* DLCI empty - try the next */
- if (len == 0)
- i++;
- else
- ret++;
- }
+ };
return ret;
}
@@ -1385,7 +1497,6 @@ 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: {
@@ -1407,9 +1518,7 @@ 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 */
- spin_lock_irqsave(&gsm->tx_lock, flags);
- gsm_data_kick(gsm, NULL);
- spin_unlock_irqrestore(&gsm->tx_lock, flags);
+ gsmld_write_trigger(gsm);
break;
case CMD_FCOFF:
/* Modem wants us to STFU */
@@ -1612,8 +1721,6 @@ static int gsm_control_wait(struct gsm_mux *gsm, struct gsm_control *control)
static void gsm_dlci_close(struct gsm_dlci *dlci)
{
- unsigned long flags;
-
del_timer(&dlci->t1);
if (debug & 8)
pr_debug("DLCI %d goes closed.\n", dlci->addr);
@@ -1622,17 +1729,16 @@ static void gsm_dlci_close(struct gsm_dlci *dlci)
dlci->constipated = true;
if (dlci->addr != 0) {
tty_port_tty_hangup(&dlci->port, false);
- spin_lock_irqsave(&dlci->lock, flags);
- kfifo_reset(&dlci->fifo);
- spin_unlock_irqrestore(&dlci->lock, flags);
+ gsm_dlci_clear_queues(dlci->gsm, dlci);
/* Ensure that gsmtty_open() can return. */
tty_port_set_initialized(&dlci->port, 0);
wake_up_interruptible(&dlci->port.open_wait);
} else
dlci->gsm->dead = true;
- wake_up(&dlci->gsm->event);
/* A DLCI 0 close is a MUX termination so we need to kick that
back to userspace somehow */
+ gsm_dlci_data_kick(dlci);
+ wake_up(&dlci->gsm->event);
}
/**
@@ -1655,6 +1761,7 @@ static void gsm_dlci_open(struct gsm_dlci *dlci)
/* Send current modem state */
if (dlci->addr)
gsm_modem_update(dlci, 0);
+ gsm_dlci_data_kick(dlci);
wake_up(&dlci->gsm->event);
}
@@ -2209,7 +2316,7 @@ static void gsm1_receive(struct gsm_mux *gsm, unsigned char c)
} else if ((c & ISO_IEC_646_MASK) == XOFF) {
gsm->constipated = false;
/* Kick the link in case it is idling */
- gsm_data_kick(gsm, NULL);
+ gsmld_write_trigger(gsm);
return;
}
if (c == GSM1_SOF) {
@@ -2340,6 +2447,9 @@ static void gsm_cleanup_mux(struct gsm_mux *gsm, bool disc)
del_timer_sync(&gsm->kick_timer);
del_timer_sync(&gsm->t2_timer);
+ /* Finish writing to ldisc */
+ flush_work(&gsm->tx_work);
+
/* Free up any link layer users and finally the control channel */
if (gsm->has_devices) {
gsm_unregister_devices(gsm_tty_driver, gsm->num);
@@ -2351,9 +2461,12 @@ static void gsm_cleanup_mux(struct gsm_mux *gsm, bool disc)
mutex_unlock(&gsm->mutex);
/* Now wipe the queues */
tty_ldisc_flush(gsm->tty);
- list_for_each_entry_safe(txq, ntxq, &gsm->tx_list, list)
+ list_for_each_entry_safe(txq, ntxq, &gsm->tx_ctrl_list, list)
+ kfree(txq);
+ INIT_LIST_HEAD(&gsm->tx_ctrl_list);
+ list_for_each_entry_safe(txq, ntxq, &gsm->tx_data_list, list)
kfree(txq);
- INIT_LIST_HEAD(&gsm->tx_list);
+ INIT_LIST_HEAD(&gsm->tx_data_list);
}
/**
@@ -2372,6 +2485,7 @@ static int gsm_activate_mux(struct gsm_mux *gsm)
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);
spin_lock_init(&gsm->control_lock);
spin_lock_init(&gsm->tx_lock);
@@ -2481,7 +2595,8 @@ static struct gsm_mux *gsm_alloc_mux(void)
spin_lock_init(&gsm->lock);
mutex_init(&gsm->mutex);
kref_init(&gsm->ref);
- INIT_LIST_HEAD(&gsm->tx_list);
+ INIT_LIST_HEAD(&gsm->tx_ctrl_list);
+ INIT_LIST_HEAD(&gsm->tx_data_list);
gsm->t1 = T1;
gsm->t2 = T2;
@@ -2639,6 +2754,47 @@ static int gsmld_output(struct gsm_mux *gsm, u8 *data, int len)
return gsm->tty->ops->write(gsm->tty, data, len);
}
+
+/**
+ * gsmld_write_trigger - schedule ldisc write task
+ * @gsm: our mux
+ */
+static void gsmld_write_trigger(struct gsm_mux *gsm)
+{
+ if (!gsm || !gsm->dlci[0] || gsm->dlci[0]->dead)
+ return;
+ schedule_work(&gsm->tx_work);
+}
+
+
+/**
+ * gsmld_write_task - ldisc write task
+ * @work: our tx write work
+ *
+ * Writes out data to the ldisc if possible. We are doing this here to
+ * avoid dead-locking. This returns if no space or data is left for output.
+ */
+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;
+ spin_lock_irqsave(&gsm->tx_lock, flags);
+ if (gsm->tty)
+ ret = gsm_data_kick(gsm);
+ spin_unlock_irqrestore(&gsm->tx_lock, flags);
+
+ if (ret >= 0)
+ for (i = 0; i < NUM_DLCI; i++)
+ if (gsm->dlci[i])
+ tty_port_tty_wakeup(&gsm->dlci[i]->port);
+}
+
/**
* gsmld_attach_gsm - mode set up
* @tty: our tty structure
@@ -2779,6 +2935,7 @@ static int gsmld_open(struct tty_struct *tty)
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);
return 0;
}
@@ -2795,16 +2952,9 @@ 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);
- spin_lock_irqsave(&gsm->tx_lock, flags);
- gsm_data_kick(gsm, NULL);
- if (gsm->tx_bytes < TX_THRESH_LO) {
- gsm_dlci_data_sweep(gsm);
- }
- spin_unlock_irqrestore(&gsm->tx_lock, flags);
+ gsmld_write_trigger(gsm);
}
/**
--
2.34.1
From: Daniel Starke <[email protected]>
The current implementation does not handle the situation that no data is in
the internal queue and needs to be sent out while the user tty fifo is
full.
Add a timer that moves more data from user tty down to the internal queue
which is then serialized on the ldisc. This timer is triggered if no data
was moved from a user tty to the internal queue within 10 * T1.
Fixes: e1eaea46bb40 ("tty: n_gsm line discipline")
Cc: [email protected]
Signed-off-by: Daniel Starke <[email protected]>
---
drivers/tty/n_gsm.c | 43 +++++++++++++++++++++++++++++++++++--------
1 file changed, 35 insertions(+), 8 deletions(-)
No changes since v2 since there was no reply on my comments.
Link: https://lore.kernel.org/all/DB9PR10MB5881A13C22F91D7F5834E71EE0D49@DB9PR10MB5881.EURPRD10.PROD.OUTLOOK.COM/
Link: https://lore.kernel.org/all/[email protected]/
diff --git a/drivers/tty/n_gsm.c b/drivers/tty/n_gsm.c
index b51e2023d88d..58bf4b4aea78 100644
--- a/drivers/tty/n_gsm.c
+++ b/drivers/tty/n_gsm.c
@@ -244,6 +244,7 @@ struct gsm_mux {
struct list_head tx_list; /* Pending data packets */
/* Control messages */
+ 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 */
@@ -833,6 +834,7 @@ static void __gsm_data_queue(struct gsm_dlci *dlci, struct gsm_msg *msg)
list_add_tail(&msg->list, &gsm->tx_list);
gsm->tx_bytes += msg->len;
gsm_data_kick(gsm, dlci);
+ mod_timer(&gsm->kick_timer, jiffies + 10 * gsm->t1 * HZ / 100);
}
/**
@@ -885,9 +887,6 @@ static int gsm_dlci_data_output(struct gsm_mux *gsm, struct gsm_dlci *dlci)
size = len + h;
msg = gsm_data_alloc(gsm, dlci->addr, size, gsm->ftype);
- /* FIXME: need a timer or something to kick this so it can't
- * get stuck with no work outstanding and no buffer free
- */
if (!msg)
return -ENOMEM;
dp = msg->data;
@@ -964,9 +963,6 @@ static int gsm_dlci_data_output_framed(struct gsm_mux *gsm,
size = len + overhead;
msg = gsm_data_alloc(gsm, dlci->addr, size, gsm->ftype);
-
- /* FIXME: need a timer or something to kick this so it can't
- get stuck with no work outstanding and no buffer free */
if (msg == NULL) {
skb_queue_tail(&dlci->skb_list, dlci->skb);
dlci->skb = NULL;
@@ -1062,9 +1058,9 @@ static int gsm_dlci_modem_output(struct gsm_mux *gsm, struct gsm_dlci *dlci,
* renegotiate DLCI priorities with optional stuff. Needs optimising.
*/
-static void gsm_dlci_data_sweep(struct gsm_mux *gsm)
+static int gsm_dlci_data_sweep(struct gsm_mux *gsm)
{
- int len;
+ int len, ret = 0;
/* Priority ordering: We should do priority with RR of the groups */
int i = 1;
@@ -1087,7 +1083,11 @@ static void gsm_dlci_data_sweep(struct gsm_mux *gsm)
/* DLCI empty - try the next */
if (len == 0)
i++;
+ else
+ ret++;
}
+
+ return ret;
}
/**
@@ -1806,6 +1806,30 @@ static void gsm_dlci_command(struct gsm_dlci *dlci, const u8 *data, int len)
}
}
+/**
+ * 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_timer(struct timer_list *t)
+{
+ struct gsm_mux *gsm = from_timer(gsm, t, kick_timer);
+ unsigned long flags;
+ int sent = 0;
+
+ 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);
+ spin_unlock_irqrestore(&gsm->tx_lock, flags);
+
+ if (sent && debug & 4)
+ pr_info("%s TX queue stalled\n", __func__);
+}
+
/*
* Allocate/Free DLCI channels
*/
@@ -2261,6 +2285,7 @@ static void gsm_cleanup_mux(struct gsm_mux *gsm, bool disc)
}
/* Finish outstanding timers, making sure they are done */
+ del_timer_sync(&gsm->kick_timer);
del_timer_sync(&gsm->t2_timer);
/* Free up any link layer users and finally the control channel */
@@ -2293,6 +2318,7 @@ static int gsm_activate_mux(struct gsm_mux *gsm)
struct gsm_dlci *dlci;
int ret;
+ timer_setup(&gsm->kick_timer, gsm_kick_timer, 0);
timer_setup(&gsm->t2_timer, gsm_control_retransmit, 0);
init_waitqueue_head(&gsm->event);
spin_lock_init(&gsm->control_lock);
@@ -2699,6 +2725,7 @@ static int gsmld_open(struct tty_struct *tty)
gsmld_attach_gsm(tty, gsm);
+ timer_setup(&gsm->kick_timer, gsm_kick_timer, 0);
timer_setup(&gsm->t2_timer, gsm_control_retransmit, 0);
return 0;
--
2.34.1
On Mon, May 30, 2022 at 04:45:09PM +0200, D. Starke wrote:
> From: Daniel Starke <[email protected]>
>
> The current implementation queues up new control and user packets as needed
> and processes this queue down to the ldisc in the same code path.
> That means that the upper and the lower layer are hard coupled in the code.
> Due to this deadlocks can happen as seen below while transmitting data,
> especially during ldisc congestion. Furthermore, the data channels starve
> the control channel on high transmission load on the ldisc.
>
> Introduce an additional control channel data queue to prevent timeouts and
> link hangups during ldisc congestion. This is being processed before the
> user channel data queue in gsm_data_kick(), i.e. with the highest priority.
> Put the queue to ldisc data path into a workqueue and trigger it whenever
> new data has been put into the transmission queue. Change
> gsm_dlci_data_sweep() accordingly to fill up the transmission queue until
> TX_THRESH_HI. This solves the locking issue, keeps latency low and provides
> good performance on high data load.
> Note that now all packets from a DLCI are removed from the internal queue
> if the associated DLCI was closed. This ensures that no data is sent by the
> introduced write task to an already closed DLCI.
>
> BUG: spinlock recursion on CPU#0, test_v24_loop/124
> lock: serial8250_ports+0x3a8/0x7500, .magic: dead4ead, .owner: test_v24_loop/124, .owner_cpu: 0
> CPU: 0 PID: 124 Comm: test_v24_loop Tainted: G O 5.18.0-rc2 #3
> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/2014
> Call Trace:
> <IRQ>
> dump_stack_lvl+0x34/0x44
> do_raw_spin_lock+0x76/0xa0
> _raw_spin_lock_irqsave+0x72/0x80
> uart_write_room+0x3b/0xc0
> gsm_data_kick+0x14b/0x240 [n_gsm]
> gsmld_write_wakeup+0x35/0x70 [n_gsm]
> tty_wakeup+0x53/0x60
> tty_port_default_wakeup+0x1b/0x30
> serial8250_tx_chars+0x12f/0x220
> serial8250_handle_irq.part.0+0xfe/0x150
> serial8250_default_handle_irq+0x48/0x80
> serial8250_interrupt+0x56/0xa0
> __handle_irq_event_percpu+0x78/0x1f0
> handle_irq_event+0x34/0x70
> handle_fasteoi_irq+0x90/0x1e0
> __common_interrupt+0x69/0x100
> common_interrupt+0x48/0xc0
> asm_common_interrupt+0x1e/0x40
> RIP: 0010:__do_softirq+0x83/0x34e
> Code: 2a 0a ff 0f b7 ed c7 44 24 10 0a 00 00 00 48 c7 c7 51 2a 64 82 e8 2d
> e2 d5 ff 65 66 c7 05 83 af 1e 7e 00 00 fb b8 ff ff ff ff <49> c7 c2 40 61
> 80 82 0f bc c5 41 89 c4 41 83 c4 01 0f 84 e6 00 00
> RSP: 0018:ffffc90000003f98 EFLAGS: 00000286
> RAX: 00000000ffffffff RBX: 0000000000000000 RCX: 0000000000000000
> RDX: 0000000000000000 RSI: ffffffff82642a51 RDI: ffffffff825bb5e7
> RBP: 0000000000000200 R08: 00000008de3271a8 R09: 0000000000000000
> R10: 0000000000000001 R11: 0000000000000000 R12: 0000000000000000
> R13: 0000000000000030 R14: 0000000000000000 R15: 0000000000000000
> ? __do_softirq+0x73/0x34e
> irq_exit_rcu+0xb5/0x100
> common_interrupt+0xa4/0xc0
> </IRQ>
> <TASK>
> asm_common_interrupt+0x1e/0x40
> RIP: 0010:_raw_spin_unlock_irqrestore+0x2e/0x50
> Code: 00 55 48 89 fd 48 83 c7 18 53 48 89 f3 48 8b 74 24 10 e8 85 28 36 ff
> 48 89 ef e8 cd 58 36 ff 80 e7 02 74 01 fb bf 01 00 00 00 <e8> 3d 97 33 ff
> 65 8b 05 96 23 2b 7e 85 c0 74 03 5b 5d c3 0f 1f 44
> RSP: 0018:ffffc9000020fd08 EFLAGS: 00000202
> RAX: 0000000000000000 RBX: 0000000000000246 RCX: 0000000000000000
> RDX: 0000000000000004 RSI: ffffffff8257fd74 RDI: 0000000000000001
> RBP: ffff8880057de3a0 R08: 00000008de233000 R09: 0000000000000000
> R10: 0000000000000001 R11: 0000000000000000 R12: 0000000000000000
> R13: 0000000000000100 R14: 0000000000000202 R15: ffff8880057df0b8
> ? _raw_spin_unlock_irqrestore+0x23/0x50
> gsmtty_write+0x65/0x80 [n_gsm]
> n_tty_write+0x33f/0x530
> ? swake_up_all+0xe0/0xe0
> file_tty_write.constprop.0+0x1b1/0x320
> ? n_tty_flush_buffer+0xb0/0xb0
> new_sync_write+0x10c/0x190
> vfs_write+0x282/0x310
> ksys_write+0x68/0xe0
> do_syscall_64+0x3b/0x90
> entry_SYSCALL_64_after_hwframe+0x44/0xae
> RIP: 0033:0x7f3e5e35c15c
> Code: 8b 7c 24 08 89 c5 e8 c5 ff ff ff 89 ef 89 44 24 08 e8 58 bc 02 00 8b
> 44 24 08 48 83 c4 10 5d c3 48 63 ff b8 01 00 00 00 0f 05 <48> 3d 00 f0 ff
> ff 76 10 48 8b 15 fd fc 05 00 f7 d8 64 89 02 48 83
> RSP: 002b:00007ffcee77cd18 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
> RAX: ffffffffffffffda RBX: 00007ffcee77cd70 RCX: 00007f3e5e35c15c
> RDX: 0000000000000100 RSI: 00007ffcee77cd90 RDI: 0000000000000003
> RBP: 0000000000000100 R08: 0000000000000000 R09: 7efefefefefefeff
> R10: 00007f3e5e3bddeb R11: 0000000000000246 R12: 00007ffcee77ce8f
> R13: 0000000000000001 R14: 000056214404e010 R15: 00007ffcee77cd90
> </TASK>
>
> Fixes: e1eaea46bb40 ("tty: n_gsm line discipline")
> Cc: [email protected]
> Signed-off-by: Daniel Starke <[email protected]>
> ---
> drivers/tty/n_gsm.c | 410 ++++++++++++++++++++++++++++++--------------
> 1 file changed, 280 insertions(+), 130 deletions(-)
This is a bit huge for stable backports, especially given that a huge
number of the previous stable backports have totally failed and no one
has submitted new versions.
So why is this needed for stable? Same for all of these in the
series...
thanks,
greg k-h
> This is a bit huge for stable backports, especially given that a huge
> number of the previous stable backports have totally failed and no one
> has submitted new versions.
>
> So why is this needed for stable? Same for all of these in the series...
Given the fact that these are all bug fixes I assumed that these are also
relevant for backporting. Maybe only in the more recent stable releases
if there are issues with the merges.
I do not mind removing the stable kernel reference and keep these changes
only for mainline. So please let me know your preference.
Should I resubmit the patches without stable reference?
Best regards,
Daniel Starke
On Thu, Jun 23, 2022 at 12:26:27PM +0000, Starke, Daniel wrote:
> > This is a bit huge for stable backports, especially given that a huge
> > number of the previous stable backports have totally failed and no one
> > has submitted new versions.
> >
> > So why is this needed for stable? Same for all of these in the series...
>
> Given the fact that these are all bug fixes I assumed that these are also
> relevant for backporting. Maybe only in the more recent stable releases
> if there are issues with the merges.
> I do not mind removing the stable kernel reference and keep these changes
> only for mainline. So please let me know your preference.
> Should I resubmit the patches without stable reference?
Please read the stable kernel rules for what is, and is not allowed.
Generally a patch that does:
drivers/tty/n_gsm.c | 410 ++++++++++++++++++++++++++++++--------------
is not allowed.
Please sort by what is stable fixes, and what is not. Given that you
don't seem to want to backport patches to older stable kernels when they
fail to apply, why are any of these needed in stable kernels if the
older ones are not also going to be merged there?
thanks,
greg k-h
> Please read the stable kernel rules for what is, and is not allowed.
> Generally a patch that does:
> drivers/tty/n_gsm.c | 410 ++++++++++++++++++++++++++++++--------------
> is not allowed.
>
> Please sort by what is stable fixes, and what is not. Given that you
> don't seem to want to backport patches to older stable kernels when they
> fail to apply, why are any of these needed in stable kernels if the older
> ones are not also going to be merged there?
Indeed, the documentation disallows such big backports as I have just found
out.
Initially, I added the stable backport remark as suggested by you for my
very first patch.
We have split our complete change set in small patches, re-ordered the
changes to submit bug fixes first and documented all changes pedantically.
Supporting all the backports turns out to come with much higher effort as
we have anticipated. We do not have the resources to support this.
For us it is sufficient to keep all our changes on the n_gsm driver in the
mainline branch. Also for all upcoming patches.
We have already done various integration tests with the final version of
the n_gsm driver with Triorail and Funkwerk mobiles. It is part of our
commercial product which has an official approval. The quality and feature
level (3GPP standard conformance) of the n_gsm driver has been
significantly improved by our changes. And we would like to share this with
the community. This would bring the n_gsm driver out of its experimental
state.
Hence, I would like to resubmit this patch series without any stable
backport remark to avoid unmanageable effort.
Best regards,
Daniel Starke
On Tue, Jun 28, 2022 at 09:41:17AM +0000, Starke, Daniel wrote:
> Hence, I would like to resubmit this patch series without any stable
> backport remark to avoid unmanageable effort.
That would be great, please do!