staging: most: allocate only all requested memory

This prohibits the allocation of the memory for the MBOs if only the
part of the MBOs, requested by the application, may be allocated.  The
function arm_mbo_chain, if cannot allocate all requested MBO, frees all
prior allocated memory and returns 0.
Signed-off-by: Andrey Shvetsov <andrey.shvetsov@k2l.de>
Signed-off-by: Christian Gromm <christian.gromm@microchip.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/most/core.c

@@ -952,18 +952,17 @@ static int arm_mbo_chain(struct most_channel *c, int dir,
 			 void (*compl)(struct mbo *))
 {
 	unsigned int i;
-	int retval;
 	struct mbo *mbo;
+	unsigned long flags;
 	u32 coherent_buf_size = c->cfg.buffer_size + c->cfg.extra_len;
 
 	atomic_set(&c->mbo_nq_level, 0);
 
 	for (i = 0; i < c->cfg.num_buffers; i++) {
 		mbo = kzalloc(sizeof(*mbo), GFP_KERNEL);
-		if (!mbo) {
-			retval = i;
-			goto _exit;
-		}
+		if (!mbo)
+			goto flush_fifos;
+
 		mbo->context = c;
 		mbo->ifp = c->iface;
 		mbo->hdm_channel_id = c->channel_id;
@@ -971,26 +970,28 @@ static int arm_mbo_chain(struct most_channel *c, int dir,
 						       coherent_buf_size,
 						       &mbo->bus_address,
 						       GFP_KERNEL);
-		if (!mbo->virt_address) {
-			pr_info("WARN: No DMA coherent buffer.\n");
-			retval = i;
-			goto _error1;
-		}
+		if (!mbo->virt_address)
+			goto release_mbo;
+
 		mbo->complete = compl;
 		mbo->num_buffers_ptr = &dummy_num_buffers;
 		if (dir == MOST_CH_RX) {
 			nq_hdm_mbo(mbo);
 			atomic_inc(&c->mbo_nq_level);
 		} else {
-			arm_mbo(mbo);
+			spin_lock_irqsave(&c->fifo_lock, flags);
+			list_add_tail(&mbo->list, &c->fifo);
+			spin_unlock_irqrestore(&c->fifo_lock, flags);
 		}
 	}
-	return i;
+	return c->cfg.num_buffers;
 
-_error1:
+release_mbo:
 	kfree(mbo);
-_exit:
-	return retval;
+
+flush_fifos:
+	flush_channel_fifos(c);
+	return 0;
 }
 
 /**