ice: cleanup allocations in ice_ptp_alloc_tx_tracker

The ice_ptp_alloc_tx_tracker function must allocate the timestamp array and
the bitmap for tracking the currently in use indexes. A future change is
going to add yet another allocation to this function.

If these allocations fail we need to ensure that we properly cleanup and
ensure that the pointers in the ice_ptp_tx structure are NULL.

Simplify this logic by allocating to local variables first. If any
allocation fails, then free everything and exit. Only update the ice_ptp_tx
structure if all allocations succeed.

This ensures that we have no side effects on the Tx structure unless all
allocations have succeeded. Thus, no code will see an invalid pointer and
we don't need to re-assign NULL on cleanup.

This is safe because kernel "free" functions are designed to be NULL safe
and perform no action if passed a NULL pointer. Thus its safe to simply
always call kfree or bitmap_free even if one of those pointers was NULL.
Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Tested-by: Gurucharan G <gurucharanx.g@intel.com> (A Contingent worker at Intel)
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>

drivers/net/ethernet/intel/ice/ice_ptp.c

@@ -794,17 +794,21 @@ static bool ice_ptp_tx_tstamp(struct ice_ptp_tx *tx)
 static int
 ice_ptp_alloc_tx_tracker(struct ice_ptp_tx *tx)
 {
-	tx->tstamps = kcalloc(tx->len, sizeof(*tx->tstamps), GFP_KERNEL);
-	if (!tx->tstamps)
-		return -ENOMEM;
+	struct ice_tx_tstamp *tstamps;
+	unsigned long *in_use;
+
+	tstamps = kcalloc(tx->len, sizeof(*tstamps), GFP_KERNEL);
+	in_use = bitmap_zalloc(tx->len, GFP_KERNEL);
+
+	if (!tstamps || !in_use) {
+		kfree(tstamps);
+		bitmap_free(in_use);
 
-	tx->in_use = bitmap_zalloc(tx->len, GFP_KERNEL);
-	if (!tx->in_use) {
-		kfree(tx->tstamps);
-		tx->tstamps = NULL;
 		return -ENOMEM;
 	}
 
+	tx->tstamps = tstamps;
+	tx->in_use = in_use;
 	tx->init = 1;
 
 	spin_lock_init(&tx->lock);