netdev - [PATCH net 1/1] ibmvnic: don't release napi in __ibmvnic

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Date:   Mon,  7 Feb 2022 16:19:18 -0800
From:   Sukadev Bhattiprolu <sukadev@...ux.ibm.com>
To:     netdev@...r.kernel.org
Cc:     Brian King <brking@...ux.ibm.com>, Dany Madden <drt@...ux.ibm.com>,
        Rick Lindsley <ricklind@...ux.ibm.com>, abdhalee@...ibm.com,
        vaish123@...ibm.com, Abdul Haleem <abdhalee@...ux.vnet.ibm.com>
Subject: [PATCH net 1/1] ibmvnic: don't release napi in __ibmvnic_open()

If __ibmvnic_open() encounters an error such as when setting link state,
it calls release_resources() which frees the napi structures needlessly.
Instead, have __ibmvnic_open() only clean up the work it did so far (i.e.
disable napi and irqs) and leave the rest to the callers.

If caller of __ibmvnic_open() is ibmvnic_open(), it should release the
resources immediately. If the caller is do_reset() or do_hard_reset(),
they will release the resources on the next reset.

This fixes following crash that occured when running the drmgr command
several times to add/remove a vnic interface:

	[102056] ibmvnic 30000003 env3: Disabling rx_scrq[6] irq
	[102056] ibmvnic 30000003 env3: Disabling rx_scrq[7] irq
	[102056] ibmvnic 30000003 env3: Replenished 8 pools
	Kernel attempted to read user page (10) - exploit attempt? (uid: 0)
	BUG: Kernel NULL pointer dereference on read at 0x00000010
	Faulting instruction address: 0xc000000000a3c840
	Oops: Kernel access of bad area, sig: 11 [#1]
	LE PAGE_SIZE=64K MMU=Radix SMP NR_CPUS=2048 NUMA pSeries
	...
	CPU: 9 PID: 102056 Comm: kworker/9:2 Kdump: loaded Not tainted 5.16.0-rc5-autotest-g6441998e2e37 #1
	Workqueue: events_long __ibmvnic_reset [ibmvnic]
	NIP:  c000000000a3c840 LR: c0080000029b5378 CTR: c000000000a3c820
	REGS: c0000000548e37e0 TRAP: 0300   Not tainted  (5.16.0-rc5-autotest-g6441998e2e37)
	MSR:  8000000000009033 <SF,EE,ME,IR,DR,RI,LE>  CR: 28248484  XER: 00000004
	CFAR: c0080000029bdd24 DAR: 0000000000000010 DSISR: 40000000 IRQMASK: 0 
	GPR00: c0080000029b55d0 c0000000548e3a80 c0000000028f0200 0000000000000000 
	...
	NIP [c000000000a3c840] napi_enable+0x20/0xc0
	LR [c0080000029b5378] __ibmvnic_open+0xf0/0x430 [ibmvnic]
	Call Trace:
	[c0000000548e3a80] [0000000000000006] 0x6 (unreliable)
	[c0000000548e3ab0] [c0080000029b55d0] __ibmvnic_open+0x348/0x430 [ibmvnic]
	[c0000000548e3b40] [c0080000029bcc28] __ibmvnic_reset+0x500/0xdf0 [ibmvnic]
	[c0000000548e3c60] [c000000000176228] process_one_work+0x288/0x570
	[c0000000548e3d00] [c000000000176588] worker_thread+0x78/0x660
	[c0000000548e3da0] [c0000000001822f0] kthread+0x1c0/0x1d0
	[c0000000548e3e10] [c00000000000cf64] ret_from_kernel_thread+0x5c/0x64
	Instruction dump:
	7d2948f8 792307e0 4e800020 60000000 3c4c01eb 384239e0 f821ffd1 39430010 
	38a0fff6 e92d1100 f9210028 39200000 <e9030010> f9010020 60420000 e9210020 
	---[ end trace 5f8033b08fd27706 ]---

Fixes: ed651a10875f ("ibmvnic: Updated reset handling)
Reported-by: Abdul Haleem <abdhalee@...ux.vnet.ibm.com>
Signed-off-by: Sukadev Bhattiprolu <sukadev@...ux.ibm.com>
---
 drivers/net/ethernet/ibm/ibmvnic.c | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/drivers/net/ethernet/ibm/ibmvnic.c b/drivers/net/ethernet/ibm/ibmvnic.c
index f5d1ba9bea48..50d2e48274eb 100644
--- a/drivers/net/ethernet/ibm/ibmvnic.c
+++ b/drivers/net/ethernet/ibm/ibmvnic.c
@@ -110,6 +110,7 @@ static void ibmvnic_tx_scrq_clean_buffer(struct ibmvnic_adapter *adapter,
 					 struct ibmvnic_sub_crq_queue *tx_scrq);
 static void free_long_term_buff(struct ibmvnic_adapter *adapter,
 				struct ibmvnic_long_term_buff *ltb);
+static void ibmvnic_disable_irqs(struct ibmvnic_adapter *adapter);
 
 struct ibmvnic_stat {
 	char name[ETH_GSTRING_LEN];
@@ -1424,7 +1425,7 @@ static int __ibmvnic_open(struct net_device *netdev)
 	rc = set_link_state(adapter, IBMVNIC_LOGICAL_LNK_UP);
 	if (rc) {
 		ibmvnic_napi_disable(adapter);
-		release_resources(adapter);
+		ibmvnic_disable_irqs(adapter);
 		return rc;
 	}
 
@@ -1474,9 +1475,6 @@ static int ibmvnic_open(struct net_device *netdev)
 		rc = init_resources(adapter);
 		if (rc) {
 			netdev_err(netdev, "failed to initialize resources\n");
-			release_resources(adapter);
-			release_rx_pools(adapter);
-			release_tx_pools(adapter);
 			goto out;
 		}
 	}
@@ -1493,6 +1491,13 @@ static int ibmvnic_open(struct net_device *netdev)
 		adapter->state = VNIC_OPEN;
 		rc = 0;
 	}
+
+	if (rc) {
+		release_resources(adapter);
+		release_rx_pools(adapter);
+		release_tx_pools(adapter);
+	}
+
 	return rc;
 }
 
-- 
2.27.0