add support of LwIP's "lightweight" synchronization mechanisms

lwip/src/arch/sys_arch.c

@@ -74,13 +74,16 @@ sys_msleep(u32_t ms)
   }
 }
 
-/* sys_thread_new(): Spawns a new thread with given attributes as supportet
+/* sys_thread_new(): Spawns a new thread with given attributes as supported
  * Note: In MetalSVM this is realized as kernel tasks
  */
 sys_thread_t sys_thread_new(const char *name, lwip_thread_fn thread, void *arg, int stacksize, int prio)
 {
 	tid_t	tmp;
+
+	kprintf("Create LWIP task %s\n", name);
 	create_kernel_task(&tmp,thread,arg);
+
 	return tmp;
 }
 
@@ -252,4 +255,21 @@ err_t sys_mutex_new(sys_mutex_t * mutex)
 	return 0;
 }
 
+#if SYS_LIGHTWEIGHT_PROT
+#if MAX_CORES > 1
+static spinlock_irqsave_t lwprot_lock = SPINLOCK_IRQSAVE_INIT;
+
+sys_prot_t sys_arch_protect(void)
+{
+		spinlock_irqsave_lock(&lwprot_lock);
+		return 0;
+}
+
+void sys_arch_unprotect(sys_prot_t pval)
+{
+		spinlock_irqsave_unlock(&lwprot_lock);
+}
+#endif
+#endif
+
 #endif /* !NO_SYS */

lwip/src/include/arch/sys_arch.h

@@ -4,6 +4,7 @@
 #include <asm/tasks.h>
 #include <metalsvm/mailbox.h>
 #include <metalsvm/errno.h>
+#include <asm/irqflags.h>
 
 #define EWOULDBLOCK	EAGAIN	/* Operation would block */
 
@@ -22,4 +23,24 @@ typedef struct
 
 typedef tid_t*		sys_thread_t;
 
+#if SYS_LIGHTWEIGHT_PROT
+#if MAX_CORES > 1
+typedef uint32_t sys_prot_t;
+sys_prot_t sys_arch_protect(void);
+void sys_arch_unprotect(sys_prot_t pval);
+#else
+typedef uint32_t sys_prot_t;
+
+static inline sys_prot_t sys_arch_protect(void)
+{
+	return irq_nested_disable();
+}
+
+static inline void sys_arch_unprotect(sys_prot_t pval)
+{
+	irq_nested_enable(pval);
+}
+#endif
+#endif
+
 #endif /* __ARCH_SYS_ARCH_H__ */

lwip/src/include/lwipopts.h

@@ -3,6 +3,13 @@
 #ifndef __LWIPOPTS_H__
 #define __LWIPOPTS_H_
 
+/**
+ * SYS_LIGHTWEIGHT_PROT==1: if you want inter-task protection for certain
+ * critical regions during buffer allocation, deallocation and memory
+ * allocation and deallocation.
+ */
+#define SYS_LIGHTWEIGHT_PROT	1
+
 /** 
  * NO_SYS==1: Provides VERY minimal functionality. Otherwise,
  * use lwIP facilities.