From 43f301b2de7af71c309c55f0f2158a0e0aa3098d Mon Sep 17 00:00:00 2001
From: clemenkl <71892432+clemenkl@users.noreply.github.com>
Date: Wed, 5 May 2021 10:41:36 +0200
Subject: [PATCH] fix DMA deadlock size <= 0

When passed a size of 0 or less, spin__memcpy_nonblk will deadlock.
Fixed by adding a case distinction over the size. The expectation is, that the if statement nearly always evaluates to 1.
---
 sw/runtime/include/handler.h | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/sw/runtime/include/handler.h b/sw/runtime/include/handler.h
index a8c3d6e..17f463f 100644
--- a/sw/runtime/include/handler.h
+++ b/sw/runtime/include/handler.h
@@ -88,8 +88,14 @@ typedef struct spin_rw_lock {
 
 static inline int spin_dma(void* source, void* dest, size_t size, int direction, int options, spin_dma_t* xfer)
 {
-    *xfer = spin__memcpy_nonblk(source, dest, (uint32_t)size);
-    return SPIN_OK;
+    if (__builtin_expect(size>0, 1))
+    {
+        *xfer = spin__memcpy_nonblk(source, dest, (uint32_t)size);
+        return SPIN_OK;
+    } else
+    {
+        return SPIN_FAIL;  
+    }
 }
 
 static inline int spin_dma_wait(spin_dma_t xfer)