IB/hfi1: Add a safe wrapper for _rcd_get_by_index

hfi1_rcd_get_by_index assumes that the given index is in the correct
range.  In most cases this is correct because the index is bounded by
a loop.  For these cases, adding a range check to the function is
redundant.

For the use case that is not bounded by the loop range, a _safe wrapper
function is needed to validate the index before accessing the rcd array.

Add a _safe wrapper to _get_by_index to validate the index range.

Update appropriate call sites with the new _safe function.
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Signed-off-by: Michael J. Ruhl <michael.j.ruhl@intel.com>
Signed-off-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>

drivers/infiniband/hw/hfi1/chip.c

@@ -13065,7 +13065,7 @@ static int request_msix_irqs(struct hfi1_devdata *dd)
 			me->type = IRQ_SDMA;
 		} else if (first_rx <= i && i < last_rx) {
 			idx = i - first_rx;
-			rcd = hfi1_rcd_get_by_index(dd, idx);
+			rcd = hfi1_rcd_get_by_index_safe(dd, idx);
 			if (rcd) {
 				/*
 				 * Set the interrupt register and mask for this

drivers/infiniband/hw/hfi1/debugfs.c

@@ -243,7 +243,7 @@ static int _ctx_stats_seq_show(struct seq_file *s, void *v)
 	spos = v;
 	i = *spos;
 
-	rcd = hfi1_rcd_get_by_index(dd, i);
+	rcd = hfi1_rcd_get_by_index_safe(dd, i);
 	if (!rcd)
 		return SEQ_SKIP;
 
@@ -402,7 +402,7 @@ static int _rcds_seq_show(struct seq_file *s, void *v)
 	loff_t *spos = v;
 	loff_t i = *spos;
 
-	rcd = hfi1_rcd_get_by_index(dd, i);
+	rcd = hfi1_rcd_get_by_index_safe(dd, i);
 	if (rcd)
 		seqfile_dump_rcd(s, rcd);
 	hfi1_rcd_put(rcd);

drivers/infiniband/hw/hfi1/driver.c

@@ -866,7 +866,7 @@ static inline void set_nodma_rtail(struct hfi1_devdata *dd, u16 ctxt)
 	 * interrupt handler for all statically allocated kernel contexts.
 	 */
 	if (ctxt >= dd->first_dyn_alloc_ctxt) {
-		rcd = hfi1_rcd_get_by_index(dd, ctxt);
+		rcd = hfi1_rcd_get_by_index_safe(dd, ctxt);
 		if (rcd) {
 			rcd->do_interrupt =
 				&handle_receive_interrupt_nodma_rtail;
@@ -895,7 +895,7 @@ static inline void set_dma_rtail(struct hfi1_devdata *dd, u16 ctxt)
 	 * interrupt handler for all statically allocated kernel contexts.
 	 */
 	if (ctxt >= dd->first_dyn_alloc_ctxt) {
-		rcd = hfi1_rcd_get_by_index(dd, ctxt);
+		rcd = hfi1_rcd_get_by_index_safe(dd, ctxt);
 		if (rcd) {
 			rcd->do_interrupt =
 				&handle_receive_interrupt_dma_rtail;

drivers/infiniband/hw/hfi1/hfi.h

@@ -1398,6 +1398,8 @@ void hfi1_init_pportdata(struct pci_dev *pdev, struct hfi1_pportdata *ppd,
 void hfi1_free_ctxtdata(struct hfi1_devdata *dd, struct hfi1_ctxtdata *rcd);
 int hfi1_rcd_put(struct hfi1_ctxtdata *rcd);
 void hfi1_rcd_get(struct hfi1_ctxtdata *rcd);
+struct hfi1_ctxtdata *hfi1_rcd_get_by_index_safe(struct hfi1_devdata *dd,
+						 u16 ctxt);
 struct hfi1_ctxtdata *hfi1_rcd_get_by_index(struct hfi1_devdata *dd, u16 ctxt);
 int handle_receive_interrupt(struct hfi1_ctxtdata *rcd, int thread);
 int handle_receive_interrupt_nodma_rtail(struct hfi1_ctxtdata *rcd, int thread);

drivers/infiniband/hw/hfi1/init.c

@@ -283,6 +283,27 @@ static int allocate_rcd_index(struct hfi1_devdata *dd,
 	return 0;
 }
 
+/**
+ * hfi1_rcd_get_by_index_safe - validate the ctxt index before accessing the
+ * array
+ * @dd: pointer to a valid devdata structure
+ * @ctxt: the index of an possilbe rcd
+ *
+ * This is a wrapper for hfi1_rcd_get_by_index() to validate that the given
+ * ctxt index is valid.
+ *
+ * The caller is responsible for making the _put().
+ *
+ */
+struct hfi1_ctxtdata *hfi1_rcd_get_by_index_safe(struct hfi1_devdata *dd,
+						 u16 ctxt)
+{
+	if (ctxt < dd->num_rcv_contexts)
+		return hfi1_rcd_get_by_index(dd, ctxt);
+
+	return NULL;
+}
+
 /**
  * hfi1_rcd_get_by_index
  * @dd: pointer to a valid devdata structure