From: Jack Lange <jacklange@cs.pitt.edu>
Date: Wed, 4 Jul 2012 22:03:15 +0000 (-0400)
Subject: make bitmap operations atomic, fixes potential barrier race condition
X-Git-Url: http://v3vee.org/palacios/gitweb/gitweb.cgi?a=commitdiff_plain;h=7ec6a6ee7f4a472587d49ddca3a9f5b587371fd5;p=palacios.releases.git

make bitmap operations atomic, fixes potential barrier race condition
---

diff --git a/palacios/include/palacios/vmm_bitmap.h b/palacios/include/palacios/vmm_bitmap.h
index 29cabb7..04ae22d 100644
--- a/palacios/include/palacios/vmm_bitmap.h
+++ b/palacios/include/palacios/vmm_bitmap.h
@@ -24,10 +24,12 @@
 
 #ifdef __V3VEE__
 #include <palacios/vmm_types.h>
+#include <palacios/vmm_lock.h>
 
 
 
 struct v3_bitmap {
+    v3_lock_t lock; 
     int num_bits;      // number of valid bit positions in the bitmap
     uint8_t * bits;   // actual bitmap. Dynamically allocated... ugly
 };
diff --git a/palacios/src/palacios/vmm_bitmap.c b/palacios/src/palacios/vmm_bitmap.c
index 14b042d..ff7a7a7 100644
--- a/palacios/src/palacios/vmm_bitmap.c
+++ b/palacios/src/palacios/vmm_bitmap.c
@@ -24,9 +24,11 @@
 int v3_bitmap_init(struct v3_bitmap * bitmap, int num_bits) {
     int num_bytes = (num_bits / 8) + ((num_bits % 8) > 0);
 
+    v3_lock_init(&(bitmap->lock));
     bitmap->num_bits = num_bits;
     bitmap->bits = V3_Malloc(num_bytes);
 
+
     if (bitmap->bits == NULL) {
 	PrintError("Could not allocate bitmap of %d bits\n", num_bits);
 	return -1;
@@ -55,6 +57,7 @@ int v3_bitmap_set(struct v3_bitmap * bitmap, int index) {
     int major = index / 8;
     int minor = index % 8;
     int old_val = 0;
+    uint32_t flags = 0;
 
     if (index > (bitmap->num_bits - 1)) {
 	PrintError("Index out of bitmap range: (pos = %d) (num_bits = %d)\n", 
@@ -62,9 +65,14 @@ int v3_bitmap_set(struct v3_bitmap * bitmap, int index) {
 	return -1;
     }
 
+
+    flags = v3_lock_irqsave(bitmap->lock);
+
     old_val = (bitmap->bits[major] & (0x1 << minor));
     bitmap->bits[major] |= (0x1 << minor);
 
+    v3_unlock_irqrestore(bitmap->lock, flags);
+
     return old_val;
 }
 
@@ -73,6 +81,7 @@ int v3_bitmap_clear(struct v3_bitmap * bitmap, int index) {
     int major = index / 8;
     int minor = index % 8;
     int old_val = 0;
+    uint32_t flags = 0;
 
     if (index > (bitmap->num_bits - 1)) {
 	PrintError("Index out of bitmap range: (pos = %d) (num_bits = %d)\n", 
@@ -80,9 +89,13 @@ int v3_bitmap_clear(struct v3_bitmap * bitmap, int index) {
 	return -1;
     }
 
+    flags = v3_lock_irqsave(bitmap->lock);
+
     old_val = (bitmap->bits[major] & (0x1 << minor));
     bitmap->bits[major] &= ~(0x1 << minor);
 
+    v3_unlock_irqrestore(bitmap->lock, flags);
+
     return old_val;
 }