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RD Babieragregkh
RD Babiera
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gregkh
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usb: typec: tcpm: move tcpm_queue_vdm_unlocked to asynchronous work
A state check was previously added to tcpm_queue_vdm_unlocked to prevent a deadlock where the DisplayPort Alt Mode driver would be executing work and attempting to grab the tcpm_lock while the TCPM was holding the lock and attempting to unregister the altmode, blocking on the altmode driver's cancel_work_sync call. Because the state check isn't protected, there is a small window where the Alt Mode driver could determine that the TCPM is in a ready state and attempt to grab the lock while the TCPM grabs the lock and changes the TCPM state to one that causes the deadlock. The callstack is provided below: [110121.667392][ C7] Call trace: [110121.667396][ C7] __switch_to+0x174/0x338 [110121.667406][ C7] __schedule+0x608/0x9f0 [110121.667414][ C7] schedule+0x7c/0xe8 [110121.667423][ C7] kernfs_drain+0xb0/0x114 [110121.667431][ C7] __kernfs_remove+0x16c/0x20c [110121.667436][ C7] kernfs_remove_by_name_ns+0x74/0xe8 [110121.667442][ C7] sysfs_remove_group+0x84/0xe8 [110121.667450][ C7] sysfs_remove_groups+0x34/0x58 [110121.667458][ C7] device_remove_groups+0x10/0x20 [110121.667464][ C7] device_release_driver_internal+0x164/0x2e4 [110121.667475][ C7] device_release_driver+0x18/0x28 [110121.667484][ C7] bus_remove_device+0xec/0x118 [110121.667491][ C7] device_del+0x1e8/0x4ac [110121.667498][ C7] device_unregister+0x18/0x38 [110121.667504][ C7] typec_unregister_altmode+0x30/0x44 [110121.667515][ C7] tcpm_reset_port+0xac/0x370 [110121.667523][ C7] tcpm_snk_detach+0x84/0xb8 [110121.667529][ C7] run_state_machine+0x4c0/0x1b68 [110121.667536][ C7] tcpm_state_machine_work+0x94/0xe4 [110121.667544][ C7] kthread_worker_fn+0x10c/0x244 [110121.667552][ C7] kthread+0x104/0x1d4 [110121.667557][ C7] ret_from_fork+0x10/0x20 [110121.667689][ C7] Workqueue: events dp_altmode_work [110121.667697][ C7] Call trace: [110121.667701][ C7] __switch_to+0x174/0x338 [110121.667710][ C7] __schedule+0x608/0x9f0 [110121.667717][ C7] schedule+0x7c/0xe8 [110121.667725][ C7] schedule_preempt_disabled+0x24/0x40 [110121.667733][ C7] __mutex_lock+0x408/0xdac [110121.667741][ C7] __mutex_lock_slowpath+0x14/0x24 [110121.667748][ C7] mutex_lock+0x40/0xec [110121.667757][ C7] tcpm_altmode_enter+0x78/0xb4 [110121.667764][ C7] typec_altmode_enter+0xdc/0x10c [110121.667769][ C7] dp_altmode_work+0x68/0x164 [110121.667775][ C7] process_one_work+0x1e4/0x43c [110121.667783][ C7] worker_thread+0x25c/0x430 [110121.667789][ C7] kthread+0x104/0x1d4 [110121.667794][ C7] ret_from_fork+0x10/0x20 Change tcpm_queue_vdm_unlocked to queue for tcpm_queue_vdm_work, which can perform the state check while holding the TCPM lock while the Alt Mode lock is no longer held. This requires a new struct to hold the vdm data, altmode_vdm_event. Fixes: cdc9946 ("usb: typec: tcpm: enforce ready state when queueing alt mode vdm") Cc: stable <[email protected]> Signed-off-by: RD Babiera <[email protected]> Reviewed-by: Heikki Krogerus <[email protected]> Reviewed-by: Badhri Jagan Sridharan <[email protected]> Link: https://lore.kernel.org/r/[email protected] Signed-off-by: Greg Kroah-Hartman <[email protected]>
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‎drivers/usb/typec/tcpm/tcpm.c

Lines changed: 71 additions & 20 deletions
Original file line numberDiff line numberDiff line change
@@ -597,6 +597,15 @@ struct pd_rx_event {
597597
enum tcpm_transmit_type rx_sop_type;
598598
};
599599

600+
struct altmode_vdm_event {
601+
struct kthread_work work;
602+
struct tcpm_port *port;
603+
u32 header;
604+
u32 *data;
605+
int cnt;
606+
enum tcpm_transmit_type tx_sop_type;
607+
};
608+
600609
static const char * const pd_rev[] = {
601610
[PD_REV10] = "rev1",
602611
[PD_REV20] = "rev2",
@@ -1610,18 +1619,68 @@ static void tcpm_queue_vdm(struct tcpm_port *port, const u32 header,
16101619
mod_vdm_delayed_work(port, 0);
16111620
}
16121621

1613-
static void tcpm_queue_vdm_unlocked(struct tcpm_port *port, const u32 header,
1614-
const u32 *data, int cnt, enum tcpm_transmit_type tx_sop_type)
1622+
static void tcpm_queue_vdm_work(struct kthread_work *work)
16151623
{
1616-
if (port->state != SRC_READY && port->state != SNK_READY &&
1617-
port->state != SRC_VDM_IDENTITY_REQUEST)
1618-
return;
1624+
struct altmode_vdm_event *event = container_of(work,
1625+
struct altmode_vdm_event,
1626+
work);
1627+
struct tcpm_port *port = event->port;
16191628

16201629
mutex_lock(&port->lock);
1621-
tcpm_queue_vdm(port, header, data, cnt, tx_sop_type);
1630+
if (port->state != SRC_READY && port->state != SNK_READY &&
1631+
port->state != SRC_VDM_IDENTITY_REQUEST) {
1632+
tcpm_log_force(port, "dropping altmode_vdm_event");
1633+
goto port_unlock;
1634+
}
1635+
1636+
tcpm_queue_vdm(port, event->header, event->data, event->cnt, event->tx_sop_type);
1637+
1638+
port_unlock:
1639+
kfree(event->data);
1640+
kfree(event);
16221641
mutex_unlock(&port->lock);
16231642
}
16241643

1644+
static int tcpm_queue_vdm_unlocked(struct tcpm_port *port, const u32 header,
1645+
const u32 *data, int cnt, enum tcpm_transmit_type tx_sop_type)
1646+
{
1647+
struct altmode_vdm_event *event;
1648+
u32 *data_cpy;
1649+
int ret = -ENOMEM;
1650+
1651+
event = kzalloc(sizeof(*event), GFP_KERNEL);
1652+
if (!event)
1653+
goto err_event;
1654+
1655+
data_cpy = kcalloc(cnt, sizeof(u32), GFP_KERNEL);
1656+
if (!data_cpy)
1657+
goto err_data;
1658+
1659+
kthread_init_work(&event->work, tcpm_queue_vdm_work);
1660+
event->port = port;
1661+
event->header = header;
1662+
memcpy(data_cpy, data, sizeof(u32) * cnt);
1663+
event->data = data_cpy;
1664+
event->cnt = cnt;
1665+
event->tx_sop_type = tx_sop_type;
1666+
1667+
ret = kthread_queue_work(port->wq, &event->work);
1668+
if (!ret) {
1669+
ret = -EBUSY;
1670+
goto err_queue;
1671+
}
1672+
1673+
return 0;
1674+
1675+
err_queue:
1676+
kfree(data_cpy);
1677+
err_data:
1678+
kfree(event);
1679+
err_event:
1680+
tcpm_log_force(port, "failed to queue altmode vdm, err:%d", ret);
1681+
return ret;
1682+
}
1683+
16251684
static void svdm_consume_identity(struct tcpm_port *port, const u32 *p, int cnt)
16261685
{
16271686
u32 vdo = p[VDO_INDEX_IDH];
@@ -2832,8 +2891,7 @@ static int tcpm_altmode_enter(struct typec_altmode *altmode, u32 *vdo)
28322891
header = VDO(altmode->svid, vdo ? 2 : 1, svdm_version, CMD_ENTER_MODE);
28332892
header |= VDO_OPOS(altmode->mode);
28342893

2835-
tcpm_queue_vdm_unlocked(port, header, vdo, vdo ? 1 : 0, TCPC_TX_SOP);
2836-
return 0;
2894+
return tcpm_queue_vdm_unlocked(port, header, vdo, vdo ? 1 : 0, TCPC_TX_SOP);
28372895
}
28382896

28392897
static int tcpm_altmode_exit(struct typec_altmode *altmode)
@@ -2849,18 +2907,15 @@ static int tcpm_altmode_exit(struct typec_altmode *altmode)
28492907
header = VDO(altmode->svid, 1, svdm_version, CMD_EXIT_MODE);
28502908
header |= VDO_OPOS(altmode->mode);
28512909

2852-
tcpm_queue_vdm_unlocked(port, header, NULL, 0, TCPC_TX_SOP);
2853-
return 0;
2910+
return tcpm_queue_vdm_unlocked(port, header, NULL, 0, TCPC_TX_SOP);
28542911
}
28552912

28562913
static int tcpm_altmode_vdm(struct typec_altmode *altmode,
28572914
u32 header, const u32 *data, int count)
28582915
{
28592916
struct tcpm_port *port = typec_altmode_get_drvdata(altmode);
28602917

2861-
tcpm_queue_vdm_unlocked(port, header, data, count - 1, TCPC_TX_SOP);
2862-
2863-
return 0;
2918+
return tcpm_queue_vdm_unlocked(port, header, data, count - 1, TCPC_TX_SOP);
28642919
}
28652920

28662921
static const struct typec_altmode_ops tcpm_altmode_ops = {
@@ -2884,8 +2939,7 @@ static int tcpm_cable_altmode_enter(struct typec_altmode *altmode, enum typec_pl
28842939
header = VDO(altmode->svid, vdo ? 2 : 1, svdm_version, CMD_ENTER_MODE);
28852940
header |= VDO_OPOS(altmode->mode);
28862941

2887-
tcpm_queue_vdm_unlocked(port, header, vdo, vdo ? 1 : 0, TCPC_TX_SOP_PRIME);
2888-
return 0;
2942+
return tcpm_queue_vdm_unlocked(port, header, vdo, vdo ? 1 : 0, TCPC_TX_SOP_PRIME);
28892943
}
28902944

28912945
static int tcpm_cable_altmode_exit(struct typec_altmode *altmode, enum typec_plug_index sop)
@@ -2901,18 +2955,15 @@ static int tcpm_cable_altmode_exit(struct typec_altmode *altmode, enum typec_plu
29012955
header = VDO(altmode->svid, 1, svdm_version, CMD_EXIT_MODE);
29022956
header |= VDO_OPOS(altmode->mode);
29032957

2904-
tcpm_queue_vdm_unlocked(port, header, NULL, 0, TCPC_TX_SOP_PRIME);
2905-
return 0;
2958+
return tcpm_queue_vdm_unlocked(port, header, NULL, 0, TCPC_TX_SOP_PRIME);
29062959
}
29072960

29082961
static int tcpm_cable_altmode_vdm(struct typec_altmode *altmode, enum typec_plug_index sop,
29092962
u32 header, const u32 *data, int count)
29102963
{
29112964
struct tcpm_port *port = typec_altmode_get_drvdata(altmode);
29122965

2913-
tcpm_queue_vdm_unlocked(port, header, data, count - 1, TCPC_TX_SOP_PRIME);
2914-
2915-
return 0;
2966+
return tcpm_queue_vdm_unlocked(port, header, data, count - 1, TCPC_TX_SOP_PRIME);
29162967
}
29172968

29182969
static const struct typec_cable_ops tcpm_cable_ops = {

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