scsi: megaraid_sas: reduce size of fusion_context and use kmalloc for allocation

fusion_context structure is very large around 180kB and most of the size
is contributed by log_to_span array. Move log_to_span out of fusion
context and have separate allocation for log_to_span. And use kmalloc to
allocate fusion_context.  Currently kmemleak reports 1000s of false
positives for fusion->cmd_list[]. kmemleak does not track page
allocation for fusion_context. This change will also fix the false
positives reported by kmemleak.

Ref: https://marc.info/?l=linux-scsi&m=150545293900917Reported-by: Shu Wang <shuwang@redhat.com>
Signed-off-by: Kashyap Desai <kashyap.desai@broadcom.com>
Signed-off-by: Shivasharan S <shivasharan.srikanteshwara@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/megaraid/megaraid_sas.h

@@ -2218,7 +2218,6 @@ struct megasas_instance {
 
 	/* Ptr to hba specific information */
 	void *ctrl_context;
-	u32 ctrl_context_pages;
 	struct megasas_ctrl_info *ctrl_info;
 	unsigned int msix_vectors;
 	struct megasas_irq_context irq_context[MEGASAS_MAX_MSIX_QUEUES];

drivers/scsi/megaraid/megaraid_sas_fusion.c

@@ -4502,20 +4502,31 @@ megasas_alloc_fusion_context(struct megasas_instance *instance)
 {
 	struct fusion_context *fusion;
 
-	instance->ctrl_context_pages = get_order(sizeof(struct fusion_context));
-	instance->ctrl_context = (void *)__get_free_pages(GFP_KERNEL | __GFP_ZERO,
-		instance->ctrl_context_pages);
-	if (!instance->ctrl_context) {
-		/* fall back to using vmalloc for fusion_context */
-		instance->ctrl_context = vzalloc(sizeof(struct fusion_context));
+	instance->ctrl_context = kzalloc(sizeof(struct fusion_context),
+					 GFP_KERNEL);
 	if (!instance->ctrl_context) {
-			dev_err(&instance->pdev->dev, "Failed from %s %d\n", __func__, __LINE__);
+		dev_err(&instance->pdev->dev, "Failed from %s %d\n",
+			__func__, __LINE__);
 		return -ENOMEM;
 	}
-	}
 
 	fusion = instance->ctrl_context;
 
+	fusion->log_to_span_pages = get_order(MAX_LOGICAL_DRIVES_EXT *
+					      sizeof(LD_SPAN_INFO));
+	fusion->log_to_span =
+		(PLD_SPAN_INFO)__get_free_pages(GFP_KERNEL | __GFP_ZERO,
+						fusion->log_to_span_pages);
+	if (!fusion->log_to_span) {
+		fusion->log_to_span = vzalloc(MAX_LOGICAL_DRIVES_EXT *
+					      sizeof(LD_SPAN_INFO));
+		if (!fusion->log_to_span) {
+			dev_err(&instance->pdev->dev, "Failed from %s %d\n",
+				__func__, __LINE__);
+			return -ENOMEM;
+		}
+	}
+
 	fusion->load_balance_info_pages = get_order(MAX_LOGICAL_DRIVES_EXT *
 		sizeof(struct LD_LOAD_BALANCE_INFO));
 	fusion->load_balance_info =
@@ -4546,11 +4557,15 @@ megasas_free_fusion_context(struct megasas_instance *instance)
 					fusion->load_balance_info_pages);
 		}
 
-		if (is_vmalloc_addr(fusion))
-			vfree(fusion);
+		if (fusion->log_to_span) {
+			if (is_vmalloc_addr(fusion->log_to_span))
+				vfree(fusion->log_to_span);
 			else
-			free_pages((ulong)fusion,
-				instance->ctrl_context_pages);
+				free_pages((ulong)fusion->log_to_span,
+					   fusion->log_to_span_pages);
+		}
+
+		kfree(fusion);
 	}
 }
 

drivers/scsi/megaraid/megaraid_sas_fusion.h

@@ -1312,7 +1312,8 @@ struct fusion_context {
 	u8 fast_path_io;
 	struct LD_LOAD_BALANCE_INFO *load_balance_info;
 	u32 load_balance_info_pages;
-	LD_SPAN_INFO log_to_span[MAX_LOGICAL_DRIVES_EXT];
+	LD_SPAN_INFO *log_to_span;
+	u32 log_to_span_pages;
 	struct LD_STREAM_DETECT **stream_detect_by_ld;
 };