Serialize malloc and free with a uspinlock

88193a49 · Silas Boyd-Wickizer · 401b5c65 · 88193a49 · 88193a49 · 88193a49
--- a/include/uspinlock.h
+++ b/include/uspinlock.h
@@ -23,3 +23,9 @@ tryacquire(struct uspinlock *lk)
 {
  return xchg32(&lk->locked, 1) == 0;
 }
+
+static void inline
+initlock(struct uspinlock *lk)
+{
+  lk->locked = 0;
+}
--- a/include/wquser.hh
+++ b/include/wquser.hh
@@ -43,7 +43,7 @@ wqlock_release(wqlock_t *lock)
 static inline void
 wqlock_init(wqlock_t *lock) 
 {
-  lock->locked = 0;
+  initlock(lock);
 }

 static void

--- a/lib/ulib.c
+++ b/lib/ulib.c
@@ -160,5 +160,7 @@ void __cxa_pure_virtual(void)
 void
 usetup(void)
 {
+  extern void initmalloc(void);
  forkt_setup(getpid());
+  initmalloc();
 }
--- a/lib/umalloc.cc
+++ b/lib/umalloc.cc
 #include "types.h"
 #include "stat.h"
 #include "user.h"
+#include "uspinlock.h"

 // Memory allocator by Kernighan and Ritchie,
 // The C programming Language, 2nd ed.  Section 8.7.
@@ -20,11 +21,14 @@ typedef union header Header;
 static Header base;
 static Header *freep;

+static struct uspinlock lock;
+
 void
 free(void *ap)
 {
  Header *bp, *p;

+  acquire(&lock);
  bp = (Header*)ap - 1;
  for(p = freep; !(bp > p && bp < p->s.ptr); p = p->s.ptr)
    if(p >= p->s.ptr && (bp > p || bp < p->s.ptr))
@@ -40,6 +44,7 @@ free(void *ap)
  } else
    p->s.ptr = bp;
  freep = p;
+  release(&lock);
 }

 static Header*
@@ -65,6 +70,7 @@ malloc(u32 nbytes)
  Header *p, *prevp;
  u32 nunits;

+  acquire(&lock);
  nunits = (nbytes + sizeof(Header) - 1)/sizeof(Header) + 1;
  if((prevp = freep) == 0){
    base.s.ptr = freep = prevp = &base;
@@ -80,10 +86,20 @@ malloc(u32 nbytes)
        p->s.size = nunits;
      }
      freep = prevp;
+      release(&lock);
      return (void*)(p + 1);
    }
    if(p == freep)
-      if((p = morecore(nunits)) == 0)
+      if((p = morecore(nunits)) == 0) {
+        release(&lock);
        return 0;
+      }
  }
 }
+
+extern "C" void initmalloc(void);
+void
+initmalloc(void)
+{
+  initlock(&lock);
+}