[PATCH 04/10] qla2xxx: Fix crash in NVME abort path

[Nilesh Javali]

From: Arun Easi <aeasi at marvell.com>

System crash was seen when I/O was run against a NVME target and when I/O
aborts were occurring.

Crash stack is:

    -- relevant crash stack --
    BUG: kernel NULL pointer dereference, address: 0000000000000010
    :
    #6 [ffffae1f8666bdd0] page_fault at ffffffffa740122e
       [exception RIP: qla_nvme_abort_work+339]
       RIP: ffffffffc0f592e3  RSP: ffffae1f8666be80  RFLAGS: 00010297
       RAX: 0000000000000000  RBX: ffff9b581fc8af80  RCX: ffffffffc0f83bd0
       RDX: 0000000000000001  RSI: ffff9b5839c6c7c8  RDI: 0000000008000000
       RBP: ffff9b6832f85000   R8: ffffffffc0f68160   R9: ffffffffc0f70652
       R10: ffffae1f862ffdc8  R11: 0000000000000300  R12: 000000000000010d
       R13: 0000000000000000  R14: ffff9b5839cea000  R15: 0ffff9b583fab170
       ORIG_RAX: ffffffffffffffff   CS: 0010  SS: 0018
    #7 [ffffae1f8666be98] process_one_work at ffffffffa6aba184
    #8 [ffffae1f8666bed8] worker_thread at ffffffffa6aba39d
    #9 [ffffae1f8666bf10] kthread at ffffffffa6ac06ed

The crash was due to a stale SRB structure access after it was aborted.
Fixed the issue by removing stale access.

Signed-off-by: Arun Easi <aeasi at marvell.com>
Signed-off-by: Nilesh Javali <njavali at marvell.com>
---
 drivers/scsi/qla2xxx/qla_nvme.c | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/drivers/scsi/qla2xxx/qla_nvme.c b/drivers/scsi/qla2xxx/qla_nvme.c
index 1c5da2dbd6f9..877b2b625020 100644
--- a/drivers/scsi/qla2xxx/qla_nvme.c
+++ b/drivers/scsi/qla2xxx/qla_nvme.c
@@ -228,6 +228,8 @@ static void qla_nvme_abort_work(struct work_struct *work)
 	fc_port_t *fcport = sp->fcport;
 	struct qla_hw_data *ha = fcport->vha->hw;
 	int rval, abts_done_called = 1;
+	bool io_wait_for_abort_done;
+	uint32_t handle;
 
 	ql_dbg(ql_dbg_io, fcport->vha, 0xffff,
 	       "%s called for sp=%p, hndl=%x on fcport=%p desc=%p deleted=%d\n",
@@ -244,12 +246,20 @@ static void qla_nvme_abort_work(struct work_struct *work)
 		goto out;
 	}
 
+	/*
+	 * sp may not be valid after abort_command if return code is either
+	 * SUCCESS or ERR_FROM_FW codes, so cache the value here.
+	 */
+	io_wait_for_abort_done = ql2xabts_wait_nvme &&
+					QLA_ABTS_WAIT_ENABLED(sp);
+	handle = sp->handle;
+
 	rval = ha->isp_ops->abort_command(sp);
 
 	ql_dbg(ql_dbg_io, fcport->vha, 0x212b,
 	    "%s: %s command for sp=%p, handle=%x on fcport=%p rval=%x\n",
 	    __func__, (rval != QLA_SUCCESS) ? "Failed to abort" : "Aborted",
-	    sp, sp->handle, fcport, rval);
+	    sp, handle, fcport, rval);
 
 	/*
 	 * If async tmf is enabled, the abort callback is called only on
@@ -264,7 +274,7 @@ static void qla_nvme_abort_work(struct work_struct *work)
 	 * are waited until ABTS complete. This kref is decreased
 	 * at qla24xx_abort_sp_done function.
 	 */
-	if (abts_done_called && ql2xabts_wait_nvme && QLA_ABTS_WAIT_ENABLED(sp))
+	if (abts_done_called && io_wait_for_abort_done)
 		return;
 out:
 	/* kref_get was done before work was schedule. */
-- 
2.19.0.rc0