bug 202553, replace reference mutex with atomic calls in PK11SlotInfo

r=relyea,wtc

2 files changed, 6 insertions, 24 deletions

diff --git a/security/nss/lib/pk11wrap/pk11slot.c b/security/nss/lib/pk11wrap/pk11slot.c
index 85734b8f0..b32f83211 100644
--- a/security/nss/lib/pk11wrap/pk11slot.c
+++ b/security/nss/lib/pk11wrap/pk11slot.c
@@ -51,6 +51,7 @@
 #include "secerr.h"
 #define NSSCKT_H /* we included pkcs11t.h, so block ckt.h from including nssckt.h */
 #include "ckt.h"
+#include "pratom.h"
 
 
 /*************************************************************
@@ -382,27 +383,19 @@ PK11_NewSlotInfo(void)
     if (slot == NULL) return slot;
 
 #ifdef PKCS11_USE_THREADS
-    slot->refLock = PZ_NewLock(nssILockSlot);
-    if (slot->refLock == NULL) {
-	PORT_Free(slot);
-	return slot;
-    }
     slot->sessionLock = PZ_NewLock(nssILockSession);
     if (slot->sessionLock == NULL) {
-	PZ_DestroyLock(slot->refLock);
 	PORT_Free(slot);
 	return slot;
     }
     slot->freeListLock = PZ_NewLock(nssILockFreelist);
     if (slot->freeListLock == NULL) {
 	PZ_DestroyLock(slot->sessionLock);
-	PZ_DestroyLock(slot->refLock);
 	PORT_Free(slot);
 	return slot;
     }
 #else
     slot->sessionLock = NULL;
-    slot->refLock = NULL;
     slot->freeListLock = NULL;
 #endif
     slot->freeSymKeysHead = NULL;
@@ -451,9 +444,7 @@ PK11_NewSlotInfo(void)
 PK11SlotInfo *
 PK11_ReferenceSlot(PK11SlotInfo *slot)
 {
-    PK11_USE_THREADS(PZ_Lock(slot->refLock);)
-    slot->refCount++;
-    PK11_USE_THREADS(PZ_Unlock(slot->refLock);)
+    PR_AtomicIncrement(&slot->refCount);
     return slot;
 }
 
@@ -477,10 +468,6 @@ PK11_DestroySlot(PK11SlotInfo *slot)
 	SECMOD_SlotDestroyModule(slot->module,PR_TRUE);
    }
 #ifdef PKCS11_USE_THREADS
-   if (slot->refLock) {
-	PZ_DestroyLock(slot->refLock);
-	slot->refLock = NULL;
-   }
    if (slot->sessionLock) {
 	PZ_DestroyLock(slot->sessionLock);
 	slot->sessionLock = NULL;
@@ -500,13 +487,9 @@ PK11_DestroySlot(PK11SlotInfo *slot)
 void
 PK11_FreeSlot(PK11SlotInfo *slot)
 {
-    PRBool freeit = PR_FALSE;
-
-    PK11_USE_THREADS(PZ_Lock(slot->refLock);)
-    if (slot->refCount-- == 1) freeit = PR_TRUE;
-    PK11_USE_THREADS(PZ_Unlock(slot->refLock);)
-
-    if (freeit) PK11_DestroySlot(slot);
+    if (PR_AtomicDecrement(&slot->refCount) == 0) {
+	PK11_DestroySlot(slot);
+    }
 }
 
 void
diff --git a/security/nss/lib/pk11wrap/secmodti.h b/security/nss/lib/pk11wrap/secmodti.h
index 3444bff12..ea13cd82f 100644
--- a/security/nss/lib/pk11wrap/secmodti.h
+++ b/security/nss/lib/pk11wrap/secmodti.h
@@ -81,8 +81,7 @@ struct PK11SlotInfoStr {
     unsigned long defaultFlags;
     /* keep track of who is using us so we don't accidently get freed while
      * still in use */
-    int refCount;
-    PZLock *refLock;
+    PRInt32 refCount;    /* to be in/decremented by atomic calls ONLY! */
     PZLock *freeListLock;
     PK11SymKey *freeSymKeysHead;
     int keyCount;