[PATCH] powerpc/powernv/prd: Unregister OPAL_MSG_PRD2 notifier during module unload

[Vasant Hegde]

Commit 587164cd, introduced new opal message type (OPAL_MSG_PRD2) and added
opal notifier. But I missed to unregister the notifier during module unload
path. This results in below call trace if you try to unload and load
opal_prd module.

Sample calltrace (modprobe -r opal_prd; modprobe opal_prd)
  [  213.335261] BUG: Unable to handle kernel data access on read at 0xc0080000192200e0
  [  213.335287] Faulting instruction address: 0xc00000000018d1cc
  [  213.335301] Oops: Kernel access of bad area, sig: 11 [#1]
  [  213.335313] LE PAGE_SIZE=64K MMU=Radix SMP NR_CPUS=2048 NUMA PowerNV
  [  213.335736] CPU: 66 PID: 7446 Comm: modprobe Kdump: loaded Tainted: G            E     5.14.0prd #759
  [  213.335772] NIP:  c00000000018d1cc LR: c00000000018d2a8 CTR: c0000000000cde10
  [  213.335805] REGS: c0000003c4c0f0a0 TRAP: 0300   Tainted: G            E      (5.14.0prd)
  [  213.335848] MSR:  9000000002009033 <SF,HV,VEC,EE,ME,IR,DR,RI,LE>  CR: 24224824  XER: 20040000
  [  213.335893] CFAR: c00000000018d2a4 DAR: c0080000192200e0 DSISR: 40000000 IRQMASK: 1
  [  213.335893] GPR00: c00000000018d2a8 c0000003c4c0f340 c000000001995300 c000000001a5ad08
  [  213.335893] GPR04: c00800000e3700d0 c0000003c4c0f434 c0000000010a8c08 6e616d6500000000
  [  213.335893] GPR08: 0000000000000000 c0080000192200d0 0000000000000001 c00800000e351020
  [  213.335893] GPR12: c0000000000cde10 c000000ffffecb80 c0000003c4c0fd00 0000000000000000
  [  213.335893] GPR16: 0000000000000990 c00800000d950000 c00800000d950990 c00000000103fd10
  [  213.335893] GPR20: c0000003c4c0fbc0 0000000000000001 c0000003c4c0fbc0 c00800000e370498
  [  213.335893] GPR24: 0000000000000000 c000000000dab5c8 c000000001a5ad18 c000000001a5ac80
  [  213.335893] GPR28: 0000000000000008 0000000000000001 c000000001a5ad00 c000000001a5ad00
  [  213.336170] NIP [c00000000018d1cc] notifier_chain_register+0x2c/0xc0
  [  213.336205] LR [c00000000018d2a8] atomic_notifier_chain_register+0x48/0x80
  [  213.336238] Call Trace:
  [  213.336255] [c0000003c4c0f340] [c000000002090610] 0xc000000002090610 (unreliable)
  [  213.336281] [c0000003c4c0f3a0] [c00000000018d2b8] atomic_notifier_chain_register+0x58/0x80
  [  213.336309] [c0000003c4c0f3f0] [c0000000000cde8c] opal_message_notifier_register+0x7c/0x1e0
  [  213.336345] [c0000003c4c0f4b0] [c00800000e3508ac] opal_prd_probe+0x84/0x150 [opal_prd]
  [  213.336382] [c0000003c4c0f530] [c00000000097acc8] platform_probe+0x78/0x130
  [  213.336416] [c0000003c4c0f5b0] [c000000000976520] really_probe+0x110/0x5d0
  [  213.336467] [c0000003c4c0f630] [c000000000976b5c] __driver_probe_device+0x17c/0x230
  [  213.336512] [c0000003c4c0f6b0] [c000000000976c70] driver_probe_device+0x60/0x130
  [  213.336556] [c0000003c4c0f700] [c00000000097746c] __driver_attach+0xfc/0x220
  [  213.336592] [c0000003c4c0f780] [c000000000972e68] bus_for_each_dev+0xa8/0x130
  [  213.336627] [c0000003c4c0f7e0] [c000000000975b04] driver_attach+0x34/0x50
  [  213.336661] [c0000003c4c0f800] [c000000000974e20] bus_add_driver+0x1b0/0x300
  [  213.336696] [c0000003c4c0f890] [c000000000978468] driver_register+0x98/0x1a0
  [  213.336732] [c0000003c4c0f900] [c00000000097a878] __platform_driver_register+0x38/0x50
  [  213.336768] [c0000003c4c0f920] [c00800000e350dc0] opal_prd_driver_init+0x34/0x50 [opal_prd]
  [  213.336804] [c0000003c4c0f940] [c000000000012410] do_one_initcall+0x60/0x2d0
  [  213.336821] [c0000003c4c0fa10] [c000000000262c8c] do_init_module+0x7c/0x320
  [  213.336845] [c0000003c4c0fa90] [c000000000266544] load_module+0x3394/0x3650
  [  213.336880] [c0000003c4c0fc90] [c000000000266b34] __do_sys_finit_module+0xd4/0x160
  [  213.336914] [c0000003c4c0fdb0] [c000000000031e00] system_call_exception+0x140/0x290
  [  213.336958] [c0000003c4c0fe10] [c00000000000c764] system_call_common+0xf4/0x258

Fixes: 587164cd ("powerpc/powernv: Add new opal message type")
Signed-off-by: Vasant Hegde <hegdevasant at linux.vnet.ibm.com>
---
 arch/powerpc/platforms/powernv/opal-prd.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/arch/powerpc/platforms/powernv/opal-prd.c b/arch/powerpc/platforms/powernv/opal-prd.c
index a191f4c60ce7..83305615db9e 100644
--- a/arch/powerpc/platforms/powernv/opal-prd.c
+++ b/arch/powerpc/platforms/powernv/opal-prd.c
@@ -393,6 +393,7 @@ static int opal_prd_probe(struct platform_device *pdev)
 	rc = opal_message_notifier_register(OPAL_MSG_PRD2, &opal_prd_event_nb);
 	if (rc) {
 		pr_err("Couldn't register PRD2 event notifier\n");
+		opal_message_notifier_unregister(OPAL_MSG_PRD, &opal_prd_event_nb);
 		return rc;
 	}
 
@@ -401,6 +402,8 @@ static int opal_prd_probe(struct platform_device *pdev)
 		pr_err("failed to register miscdev\n");
 		opal_message_notifier_unregister(OPAL_MSG_PRD,
 				&opal_prd_event_nb);
+		opal_message_notifier_unregister(OPAL_MSG_PRD2,
+				&opal_prd_event_nb);
 		return rc;
 	}
 
@@ -411,6 +414,7 @@ static int opal_prd_remove(struct platform_device *pdev)
 {
 	misc_deregister(&opal_prd_dev);
 	opal_message_notifier_unregister(OPAL_MSG_PRD, &opal_prd_event_nb);
+	opal_message_notifier_unregister(OPAL_MSG_PRD2, &opal_prd_event_nb);
 	return 0;
 }
 
-- 
2.31.1