[PATCH] PCI: Init driver override spinlock in new_id_store()

[Samiullah Khawaja <skhawaja@google.com>]

When setting new_id of a PCI device driver using sysfs a lockdep splat
occurs. This is because the new_id function new_id_store() checks for
driver_override by creating temporary pci_dev structs.

Since the newly added driver_override spinlock is not init for temporary
pci_dev structs, the lockdep splat complains about it.

Init the driver_override spinlock to fix this.

[    4.464296] INFO: trying to register non-static key.
[    4.466207] The code is fine but needs lockdep annotation, or maybe
[    4.468487] you didn't initialize this object before use?
[    4.470486] turning off the locking correctness validator.
[    4.472494] CPU: 2 UID: 0 PID: 177 Comm: liveupdate-iomm Not tainted 7.0.0+ #9 PREEMPT(full)
[    4.472497] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014
[    4.472498] Call Trace:
[    4.472501]  <TASK>
[    4.472503]  dump_stack_lvl+0x5d/0x80
[    4.472508]  register_lock_class+0x77e/0x790
[    4.472512]  ? check_prev_add+0xf4/0xd30
[    4.472513]  ? check_prev_add+0xf4/0xd30
[    4.472515]  __lock_acquire+0x3b4/0x1b80
[    4.472518]  ? raw_irqentry_exit_cond_resched+0x20/0x50
[    4.472556]  lock_acquire+0xbf/0x2e0
[    4.472558]  ? pci_match_device+0x24/0x180
[    4.472563]  _raw_spin_lock+0x30/0x40
[    4.472567]  ? pci_match_device+0x24/0x180
[    4.472569]  pci_match_device+0x24/0x180
[    4.472571]  new_id_store+0x189/0x1d0
[    4.472574]  kernfs_fop_write_iter+0x14f/0x210
[    4.472578]  vfs_write+0x263/0x5e0
[    4.472583]  ksys_write+0x79/0xf0
[    4.472585]  do_syscall_64+0x117/0xf80
[    4.472587]  ? clear_bhb_loop+0x40/0x90
[    4.472590]  entry_SYSCALL_64_after_hwframe+0x77/0x7f
[    4.472592] RIP: 0033:0x7fe7bc0beeb2
[    4.472595] Code: 18 41 8b 93 08 03 00 00 59 5e 48 83 f8 fc 75 1a 83 e2 39 83 fa 08 75 12 e8 2b ff ff ff 0f 1f 00 49 89 ca 48 8b 44 24 20 0f 05 <48> 83 c4 18 c3 66 0f 1f 84 00 00 00 00 00 48 83 ec 10 ff 74 24 18
[    4.472596] RSP: 002b:00007ffcdbb1ed80 EFLAGS: 00000202 ORIG_RAX: 0000000000000001
[    4.472598] RAX: ffffffffffffffda RBX: 00007fe7bc2415c0 RCX: 00007fe7bc0beeb2
[    4.472599] RDX: 000000000000000a RSI: 00005580955433c0 RDI: 0000000000000001
[    4.472600] RBP: 000000000000000a R08: 0000000000000000 R09: 0000000000000000
[    4.472601] R10: 0000000000000000 R11: 0000000000000202 R12: 000000000000000a
[    4.472602] R13: 00005580955433c0 R14: 000055805932493e R15: 0000558095545490
[    4.472605]  </TASK>

Fixes: cb3d1049f4ea ("driver core: generalize driver_override in struct device")
Fixes: 10a4206a2401 ("PCI: use generic driver_override infrastructure")
Signed-off-by: Samiullah Khawaja <skhawaja@google.com>
---
 drivers/pci/pci-driver.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c
index d10ece0889f0..5f453213b8c5 100644
--- a/drivers/pci/pci-driver.c
+++ b/drivers/pci/pci-driver.c
@@ -215,6 +215,11 @@ static ssize_t new_id_store(struct device_driver *driver, const char *buf,
 		pdev->subsystem_device = subdevice;
 		pdev->class = class;
 
+		/*
+		 * Initialize the embedded struct device driver_override lock to
+		 * avoid the lockdep errors.
+		 */
+		spin_lock_init(&pdev->dev.driver_override.lock);
 		if (pci_match_device(pdrv, pdev))
 			retval = -EEXIST;
 

base-commit: 254f49634ee16a731174d2ae34bc50bd5f45e731
-- 
2.54.0.545.g6539524ca2-goog