Changeset 770 for Whitix/branches/fs/fs/vfs/bcache.c

Timestamp:

07/09/08 18:46:57 (5 months ago)

Author:

mwhitworth

Message:

Fix buffer locking behaviour to avoid races.

Files:

• Whitix/branches/fs/fs/vfs/bcache.c (modified) (6 diffs)

Whitix/branches/fs/fs/vfs/bcache.c

@@ -95 +95 @@
         INIT_WAITQUEUE_ENTRY(bufferWait);
 
-        WaitAddToQueue(&buffer->waitQueue, &bufferWait);
-
         do
         {
+                WaitAddToQueue(&buffer->waitQueue, &bufferWait);
                 ThrSuspendThread(currThread);
-
-                if (!BufferLocked(buffer))
-                        break;
-
                 ThrSchedule();
         }while (BufferLocked(buffer));
@@ -157 +152 @@
 
         INIT_WAITQUEUE_HEAD(&buff->waitQueue);
+        BufferLock(buff);
         BlockAddToHashTable(buff);
 
@@ -259 +255 @@
                 return -EFAULT;
 
-        /* The buffer will be unlocked in StorageEndRequest */
-        BufferLock(buff);
+        /* Buffer should already be locked if we're coming from BlockRead */
 
         err=BlockSendRequestRaw(device,request);
@@ -308 +303 @@
 
         request=StorageBuildRequest(buff, REQUEST_READ);
-
-        BufferLock(buff);
 
         StorageDoRequest(device,request);
@@ -479 +472 @@
 {
         struct ListHead* head=BUFFER_HASH(device, blockNum);
-        struct Buffer* curr;
+        struct Buffer* curr, *ret=NULL;
+
+        PreemptDisable();
 
         ListForEachEntry(curr, head, list)
@@ -485 +480 @@
                 {
                         BufferGet(curr);
-                        return curr;
+                        ret=curr;
+                        goto out;
                 }
 
-        return NULL;
+out:
+        PreemptEnable();
+        return ret;
 }