[PATCH v2 1/2] usb: typec: tcpci: fix NULL pointer issue on shared irq case

[Xu Yang <xu.yang_2@nxp.com>]

The tcpci_irq() may meet below NULL pointer dereference issue:

[    2.641851] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000010
[    2.641951] status 0x1, 0x37f
[    2.650659] Mem abort info:
[    2.656490]   ESR = 0x0000000096000004
[    2.660230]   EC = 0x25: DABT (current EL), IL = 32 bits
[    2.665532]   SET = 0, FnV = 0
[    2.668579]   EA = 0, S1PTW = 0
[    2.671715]   FSC = 0x04: level 0 translation fault
[    2.676584] Data abort info:
[    2.679459]   ISV = 0, ISS = 0x00000004, ISS2 = 0x00000000
[    2.684936]   CM = 0, WnR = 0, TnD = 0, TagAccess = 0
[    2.689980]   GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0
[    2.695284] [0000000000000010] user address but active_mm is swapper
[    2.701632] Internal error: Oops: 0000000096000004 [#1] PREEMPT SMP
[    2.707883] Modules linked in:
[    2.710936] CPU: 1 UID: 0 PID: 87 Comm: irq/111-2-0051 Not tainted 6.12.0-rc6-06316-g7f63786ad3d1-dirty #4
[    2.720570] Hardware name: NXP i.MX93 11X11 EVK board (DT)
[    2.726040] pstate: 60400009 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
[    2.732989] pc : tcpci_irq+0x38/0x318
[    2.736647] lr : _tcpci_irq+0x14/0x20
[    2.740295] sp : ffff80008324bd30
[    2.743597] x29: ffff80008324bd70 x28: ffff800080107894 x27: ffff800082198f70
[    2.750721] x26: ffff0000050e6680 x25: ffff000004d172ac x24: ffff0000050f0000
[    2.757845] x23: ffff000004d17200 x22: 0000000000000001 x21: ffff0000050f0000
[    2.764969] x20: ffff000004d17200 x19: 0000000000000000 x18: 0000000000000001
[    2.772093] x17: 0000000000000000 x16: ffff80008183d8a0 x15: ffff00007fbab040
[    2.779217] x14: ffff00007fb918c0 x13: 0000000000000000 x12: 000000000000017a
[    2.786341] x11: 0000000000000001 x10: 0000000000000a90 x9 : ffff80008324bd00
[    2.793465] x8 : ffff0000050f0af0 x7 : ffff00007fbaa840 x6 : 0000000000000031
[    2.800589] x5 : 000000000000017a x4 : 0000000000000002 x3 : 0000000000000002
[    2.807713] x2 : ffff80008324bd3a x1 : 0000000000000010 x0 : 0000000000000000
[    2.814838] Call trace:
[    2.817273]  tcpci_irq+0x38/0x318
[    2.820583]  _tcpci_irq+0x14/0x20
[    2.823885]  irq_thread_fn+0x2c/0xa8
[    2.827456]  irq_thread+0x16c/0x2f4
[    2.830940]  kthread+0x110/0x114
[    2.834164]  ret_from_fork+0x10/0x20
[    2.837738] Code: f9426420 f9001fe0 d2800000 52800201 (f9400a60)

This may happen on shared irq case. Such as two Type-C ports share one
irq. After the first port finished tcpci_register_port(), it may trigger
interrupt. However, if the interrupt comes by chance the 2nd port finishes
devm_request_threaded_irq(), the 2nd port interrupt handler may be run at
first. Then the above issue may happen.

  devm_request_threaded_irq()
				<-- port1 irq comes
  disable_irq(client->irq);
  tcpci_register_port()

This will restore the logic to the state before commit (77e85107a771 "usb:
typec: tcpci: support edge irq").

Fixes: 77e85107a771 ("usb: typec: tcpci: support edge irq")
Cc: stable@vger.kernel.org
Signed-off-by: Xu Yang <xu.yang_2@nxp.com>

---
Changes in v2:
 - no changes
---
 drivers/usb/typec/tcpm/tcpci.c | 18 ++++++++----------
 1 file changed, 8 insertions(+), 10 deletions(-)

diff --git a/drivers/usb/typec/tcpm/tcpci.c b/drivers/usb/typec/tcpm/tcpci.c
index 2f15734a5043..db42f4bf3632 100644
--- a/drivers/usb/typec/tcpm/tcpci.c
+++ b/drivers/usb/typec/tcpm/tcpci.c
@@ -923,22 +923,20 @@ static int tcpci_probe(struct i2c_client *client)
 
 	chip->data.set_orientation = err;
 
+	chip->tcpci = tcpci_register_port(&client->dev, &chip->data);
+	if (IS_ERR(chip->tcpci))
+		return PTR_ERR(chip->tcpci);
+
 	err = devm_request_threaded_irq(&client->dev, client->irq, NULL,
 					_tcpci_irq,
 					IRQF_SHARED | IRQF_ONESHOT,
 					dev_name(&client->dev), chip);
-	if (err < 0)
+	if (err < 0) {
+		tcpci_unregister_port(chip->tcpci);
 		return err;
+	}
 
-	/*
-	 * Disable irq while registering port. If irq is configured as an edge
-	 * irq this allow to keep track and process the irq as soon as it is enabled.
-	 */
-	disable_irq(client->irq);
-	chip->tcpci = tcpci_register_port(&client->dev, &chip->data);
-	enable_irq(client->irq);
-
-	return PTR_ERR_OR_ZERO(chip->tcpci);
+	return 0;
 }
 
 static void tcpci_remove(struct i2c_client *client)
-- 
2.34.1