[PATCH] usb: dwc3: gadget: Fix suspend/resume warning when no-gadget is connected

[Michael Trimarchi <michael@amarulasolutions.com>]

This patch restore the logic but protects the variable using a spinlock
without moving the code

[   45.597274] dwc3 31000000.usb: wait for SETUP phase timed out
[   45.599140] dwc3 31000000.usb: failed to set STALL on ep0out
[   45.601069] ------------[ cut here ]------------
[   45.601073] WARNING: CPU: 0 PID: 150 at drivers/usb/dwc3/ep0.c:289 dwc3_ep0_out_start+0xcc/0xd4
[   45.601102] Modules linked in: cfg80211 rfkill ipv6 rpmsg_ctrl rpmsg_char crct10dif_ce rti_wdt k3_j72xx_bandgap rtc_ti_k3 omap_mailbox sa2ul authenc [last unloaded: ti_k3_r5_remoteproc]
[   45.601151] CPU: 0 PID: 150 Comm: sh Not tainted 6.8.0-rc5 #1
[   45.601159] Hardware name: BSH - CCM-M3 (DT)
[   45.601164] pstate: 600000c5 (nZCv daIF -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
[   45.601172] pc : dwc3_ep0_out_start+0xcc/0xd4
[   45.601179] lr : dwc3_ep0_out_start+0x50/0xd4
[   45.601186] sp : ffff8000832739e0
[   45.601189] x29: ffff8000832739e0 x28: ffff800082a21000 x27: ffff8000808dc630
[   45.601200] x26: 0000000000000002 x25: ffff800082530a44 x24: 0000000000000000
[   45.601210] x23: ffff000000e079a0 x22: ffff000000e07a68 x21: 0000000000000001
[   45.601219] x20: ffff000000e07880 x19: ffff000000e07880 x18: 0000000000000040
[   45.601229] x17: ffff7fff8e1ce000 x16: ffff800080000000 x15: fffffffffffe5260
[   45.601239] x14: 0000000000000000 x13: 206e6f204c4c4154 x12: 5320746573206f74
[   45.601249] x11: 0000000000000001 x10: 000000000000000a x9 : ffff800083273930
[   45.601259] x8 : 000000000000000a x7 : ffffffffffff3f0c x6 : ffffffffffff3f00
[   45.601268] x5 : ffffffffffff3f0c x4 : 0000000000000000 x3 : 0000000000000000
[   45.601278] x2 : 0000000000000000 x1 : ffff000004e7e600 x0 : 00000000ffffff92
[   45.601289] Call trace:
[   45.601293]  dwc3_ep0_out_start+0xcc/0xd4
[   45.601301]  dwc3_ep0_stall_and_restart+0x98/0xbc
[   45.601309]  dwc3_ep0_reset_state+0x5c/0x88
[   45.601315]  dwc3_gadget_soft_disconnect+0x144/0x160
[   45.601323]  dwc3_gadget_suspend+0x18/0xb0
[   45.601329]  dwc3_suspend_common+0x5c/0x18c
[   45.601341]  dwc3_suspend+0x20/0x44
[   45.601350]  platform_pm_suspend+0x2c/0x6c
[   45.601360]  __device_suspend+0x10c/0x34c
[   45.601372]  dpm_suspend+0x1a8/0x240
[   45.601382]  dpm_suspend_start+0x80/0x9c
[   45.601391]  suspend_devices_and_enter+0x1c4/0x584
[   45.601402]  pm_suspend+0x1b0/0x264
[   45.601408]  state_store+0x80/0xec
[   45.601415]  kobj_attr_store+0x18/0x2c
[   45.601426]  sysfs_kf_write+0x44/0x54
[   45.601434]  kernfs_fop_write_iter+0x120/0x1ec
[   45.601445]  vfs_write+0x23c/0x358
[   45.601458]  ksys_write+0x70/0x104
[   45.601467]  __arm64_sys_write+0x1c/0x28
[   45.601477]  invoke_syscall+0x48/0x114
[   45.601488]  el0_svc_common.constprop.0+0x40/0xe0
[   45.601498]  do_el0_svc+0x1c/0x28
[   45.601506]  el0_svc+0x34/0xb8
[   45.601516]  el0t_64_sync_handler+0x100/0x12c
[   45.601522]  el0t_64_sync+0x190/0x194
[   45.601531] ---[ end trace 0000000000000000 ]---
[   45.608794] Disabling non-boot CPUs ...
[   45.611029] psci: CPU1 killed (polled 0 ms)
[   45.611837] Enabling non-boot CPUs ...
[   45.612247] Detected VIPT I-cache on CPU1

Tested on a am62x board

Fixes: 61a348857e86 ("usb: dwc3: gadget: Fix NULL pointer dereference in dwc3_gadget_suspend)
Signed-off-by: Michael Trimarchi <michael@amarulasolutions.com>
---
 drivers/usb/dwc3/gadget.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
index 4c8dd6724678..4c88e44127b5 100644
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -4703,13 +4703,19 @@ int dwc3_gadget_suspend(struct dwc3 *dwc)
 	unsigned long flags;
 	int ret;
 
+	spin_lock_irqsave(&dwc->lock, flags);
+	if (!dwc->gadget_driver) {
+		spin_unlock_irqrestore(&dwc->lock, flags);
+		return 0;
+	}
+	spin_unlock_irqrestore(&dwc->lock, flags);
+
 	ret = dwc3_gadget_soft_disconnect(dwc);
 	if (ret)
 		goto err;
 
 	spin_lock_irqsave(&dwc->lock, flags);
-	if (dwc->gadget_driver)
-		dwc3_disconnect_gadget(dwc);
+	dwc3_disconnect_gadget(dwc);
 	spin_unlock_irqrestore(&dwc->lock, flags);
 
 	return 0;
-- 
2.40.1