[PATCH] IB/iser: Protect tasks cleanup in case iser connection was stopped

[lihongweizz]

From: Rock Li <lihongweizz@xxxxxxxxxx>

We met a crash issue as below:
...
 #7 [ff61b991f6f63d10] page_fault at ffffffffab80111e
    [exception RIP: iscsi_iser_cleanup_task+13]
    RIP: ffffffffc046c04d RSP: ff61b991f6f63dc0 RFLAGS: 00010246
    RAX: 0000000000000000 RBX: ff4bd0aalf7a5610 RCX: ff61b991f6f63dc8
    RDX: ff61b991f6f63d68 RSI: ff61b991f6f63d58 RDI: ff4bd0aalf6cdc00
    RBP: 0000000000000005 R8: 0000000000000073 R9: 0000000000000005
    R10: 0000000000000000 R11: 00000ccde3e0f5c0 R12: ff4bd08c0e0631f8
    R13: ff4bd0a95ffd3c78 R14: ff4bd0a95ffd3c78 R15: ff4bd0aalf6cdc00
    ORIG_RAX: ffffffffffffffff CS: 0010 SS: 0018
 #8 [ff616991f6f63dc0] __iscsi_put_task at ffffffffc0bd3652 [libiscsi]
 #9 [ff61b991f6f63e00] iscsi_put_task at ffffffffc0bd36e9 [libiscsi]
...

After analysing the vmcore, we find that the iser connection was already
stopped before abort handler running. The iser_conn is already unbindded
and released. So we add iser connection validation check inside cleanup
task to fix this corner case.

Signed-off-by: Rock Li <lihongweizz@xxxxxxxxxx>
---
 drivers/infiniband/ulp/iser/iscsi_iser.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/infiniband/ulp/iser/iscsi_iser.c b/drivers/infiniband/ulp/iser/iscsi_iser.c
index bb9aaff92ca3..35dfbf41fc40 100644
--- a/drivers/infiniband/ulp/iser/iscsi_iser.c
+++ b/drivers/infiniband/ulp/iser/iscsi_iser.c
@@ -366,7 +366,12 @@ static void iscsi_iser_cleanup_task(struct iscsi_task *task)
 	struct iscsi_iser_task *iser_task = task->dd_data;
 	struct iser_tx_desc *tx_desc = &iser_task->desc;
 	struct iser_conn *iser_conn = task->conn->dd_data;
-	struct iser_device *device = iser_conn->ib_conn.device;
+	struct iser_device *device;
+
+	/* stop connection might happens before iser cleanup work */
+	if (!iser_conn)
+		return;
+	device = iser_conn->ib_conn.device;
 
 	/* DEVICE_REMOVAL event might have already released the device */
 	if (!device)
-- 
2.27.0