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Subject[PATCH 4.19 198/245] scsi: libfc: Skip additional kref updating work event
Date
From: Javed Hasan <jhasan@marvell.com>

[ Upstream commit 823a65409c8990f64c5693af98ce0e7819975cba ]

When an rport event (RPORT_EV_READY) is updated without work being queued,
avoid taking an additional reference.

This issue was leading to memory leak. Trace from KMEMLEAK tool:

unreferenced object 0xffff8888259e8780 (size 512):
comm "kworker/2:1", jiffies 4433237386 (age 113021.971s)
hex dump (first 32 bytes):
58 0a ec cf 83 88 ff ff 00 00 00 00 00 00 00 00
01 00 00 00 08 00 00 00 13 7d f0 1e 0e 00 00 10
backtrace:
[<000000006b25760f>] fc_rport_recv_req+0x3c6/0x18f0 [libfc]
[<00000000f208d994>] fc_lport_recv_els_req+0x120/0x8a0 [libfc]
[<00000000a9c437b8>] fc_lport_recv+0xb9/0x130 [libfc]
[<00000000a9c437b8>] fc_lport_recv+0xb9/0x130 [libfc]
[<00000000ad5be37b>] qedf_ll2_process_skb+0x73d/0xad0 [qedf]
[<00000000e0eb6893>] process_one_work+0x382/0x6c0
[<000000002dfd9e21>] worker_thread+0x57/0x5c0
[<00000000b648204f>] kthread+0x1a0/0x1c0
[<0000000072f5ab20>] ret_from_fork+0x35/0x40
[<000000001d5c05d8>] 0xffffffffffffffff

Below is the log sequence which leads to memory leak. Here we get the
RPORT_EV_READY and RPORT_EV_STOP back to back, which lead to overwrite the
event RPORT_EV_READY by event RPORT_EV_STOP. Because of this, kref_count
gets incremented by 1.

kernel: host0: rport fffce5: Received PLOGI request
kernel: host0: rport fffce5: Received PLOGI in INIT state
kernel: host0: rport fffce5: Port is Ready
kernel: host0: rport fffce5: Received PRLI request while in state Ready
kernel: host0: rport fffce5: PRLI rspp type 8 active 1 passive 0
kernel: host0: rport fffce5: Received LOGO request while in state Ready
kernel: host0: rport fffce5: Delete port
kernel: host0: rport fffce5: Received PLOGI request
kernel: host0: rport fffce5: Received PLOGI in state Delete - send busy
kernel: host0: rport fffce5: work event 3
kernel: host0: rport fffce5: lld callback ev 3
kernel: host0: rport fffce5: work delete

Link: https://lore.kernel.org/r/20200626094959.32151-1-jhasan@marvell.com
Reviewed-by: Girish Basrur <gbasrur@marvell.com>
Reviewed-by: Saurav Kashyap <skashyap@marvell.com>
Reviewed-by: Shyam Sundar <ssundar@marvell.com>
Signed-off-by: Javed Hasan <jhasan@marvell.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/scsi/libfc/fc_rport.c | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/scsi/libfc/fc_rport.c b/drivers/scsi/libfc/fc_rport.c
index f39d2d62b002f..2b3239765c249 100644
--- a/drivers/scsi/libfc/fc_rport.c
+++ b/drivers/scsi/libfc/fc_rport.c
@@ -495,10 +495,11 @@ static void fc_rport_enter_delete(struct fc_rport_priv *rdata,

fc_rport_state_enter(rdata, RPORT_ST_DELETE);

- kref_get(&rdata->kref);
- if (rdata->event == RPORT_EV_NONE &&
- !queue_work(rport_event_queue, &rdata->event_work))
- kref_put(&rdata->kref, fc_rport_destroy);
+ if (rdata->event == RPORT_EV_NONE) {
+ kref_get(&rdata->kref);
+ if (!queue_work(rport_event_queue, &rdata->event_work))
+ kref_put(&rdata->kref, fc_rport_destroy);
+ }

rdata->event = event;
}
--
2.25.1


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