qla2xxx: Fix crash due to null pointer access

During code inspection, while investigating following stack trace
seen on one of the test setup, we found out there was possibility
of memory leak becuase driver was not unwinding the stack properly.

This issue has not been reproduced in a test environment or on a
customer setup.

Here's stack trace that was seen.

[1469877.797315] Call Trace:
[1469877.799940]  [<ffffffffa03ab6e9>] qla2x00_mem_alloc+0xb09/0x10c0 [qla2xxx]
[1469877.806980]  [<ffffffffa03ac50a>] qla2x00_probe_one+0x86a/0x1b50 [qla2xxx]
[1469877.814013]  [<ffffffff813b6d01>] ? __pm_runtime_resume+0x51/0xa0
[1469877.820265]  [<ffffffff8157c1f5>] ? _raw_spin_lock_irqsave+0x25/0x90
[1469877.826776]  [<ffffffff8157cd2d>] ? _raw_spin_unlock_irqrestore+0x6d/0x80
[1469877.833720]  [<ffffffff810741d1>] ? preempt_count_sub+0xb1/0x100
[1469877.839885]  [<ffffffff8157cd0c>] ? _raw_spin_unlock_irqrestore+0x4c/0x80
[1469877.846830]  [<ffffffff81319b9c>] local_pci_probe+0x4c/0xb0
[1469877.852562]  [<ffffffff810741d1>] ? preempt_count_sub+0xb1/0x100
[1469877.858727]  [<ffffffff81319c89>] pci_call_probe+0x89/0xb0

Cc: <stable@vger.kernel.org>
Signed-off-by: Quinn Tran <quinn.tran@cavium.com>
Signed-off-by: Himanshu Madhani <himanshu.madhani@cavium.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
[ bvanassche: Fixed spelling in patch description ]
Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>

drivers/scsi/qla2xxx/qla_os.c

@@ -3662,7 +3662,7 @@ qla2x00_mem_alloc(struct qla_hw_data *ha, uint16_t req_len, uint16_t rsp_len,
 				sizeof(struct ct6_dsd), 0,
 				SLAB_HWCACHE_ALIGN, NULL);
 			if (!ctx_cachep)
-				goto fail_free_gid_list;
+				goto fail_free_srb_mempool;
 		}
 		ha->ctx_mempool = mempool_create_slab_pool(SRB_MIN_REQ,
 			ctx_cachep);
@@ -3815,7 +3815,7 @@ qla2x00_mem_alloc(struct qla_hw_data *ha, uint16_t req_len, uint16_t rsp_len,
 	ha->loop_id_map = kzalloc(BITS_TO_LONGS(LOOPID_MAP_SIZE) * sizeof(long),
 	    GFP_KERNEL);
 	if (!ha->loop_id_map)
-		goto fail_async_pd;
+		goto fail_loop_id_map;
 	else {
 		qla2x00_set_reserved_loop_ids(ha);
 		ql_dbg_pci(ql_dbg_init, ha->pdev, 0x0123,
@@ -3824,6 +3824,8 @@ qla2x00_mem_alloc(struct qla_hw_data *ha, uint16_t req_len, uint16_t rsp_len,
 
 	return 0;
 
+fail_loop_id_map:
+	dma_pool_free(ha->s_dma_pool, ha->async_pd, ha->async_pd_dma);
 fail_async_pd:
 	dma_pool_free(ha->s_dma_pool, ha->ex_init_cb, ha->ex_init_cb_dma);
 fail_ex_init_cb:
@@ -3851,6 +3853,10 @@ qla2x00_mem_alloc(struct qla_hw_data *ha, uint16_t req_len, uint16_t rsp_len,
 	dma_pool_free(ha->s_dma_pool, ha->ms_iocb, ha->ms_iocb_dma);
 	ha->ms_iocb = NULL;
 	ha->ms_iocb_dma = 0;
+
+	if (ha->sns_cmd)
+		dma_free_coherent(&ha->pdev->dev, sizeof(struct sns_cmd_pkt),
+		    ha->sns_cmd, ha->sns_cmd_dma);
 fail_dma_pool:
 	if (IS_QLA82XX(ha) || ql2xenabledif) {
 		dma_pool_destroy(ha->fcp_cmnd_dma_pool);
@@ -3868,10 +3874,12 @@ qla2x00_mem_alloc(struct qla_hw_data *ha, uint16_t req_len, uint16_t rsp_len,
 	kfree(ha->nvram);
 	ha->nvram = NULL;
 fail_free_ctx_mempool:
-	mempool_destroy(ha->ctx_mempool);
+	if (ha->ctx_mempool)
+		mempool_destroy(ha->ctx_mempool);
 	ha->ctx_mempool = NULL;
 fail_free_srb_mempool:
-	mempool_destroy(ha->srb_mempool);
+	if (ha->srb_mempool)
+		mempool_destroy(ha->srb_mempool);
 	ha->srb_mempool = NULL;
 fail_free_gid_list:
 	dma_free_coherent(&ha->pdev->dev, qla2x00_gid_list_size(ha),