Bug 1447628, devslot: avoid deadlock when re-inserting a token, r=rrelyea

2 files changed, 13 insertions, 7 deletions

diff --git a/lib/dev/devslot.c b/lib/dev/devslot.c
index 2b19e3f90..ef941f9ed 100644
--- a/lib/dev/devslot.c
+++ b/lib/dev/devslot.c
@@ -96,10 +96,16 @@ nssSlot_ResetDelay(
 }
 
 static PRBool
-within_token_delay_period(const NSSSlot *slot)
+token_status_checked(const NSSSlot *slot)
 {
     PRIntervalTime time;
     int lastPingState = slot->lastTokenPingState;
+    /* When called from the same thread, that means
+     * nssSlot_IsTokenPresent() is called recursively through
+     * nssSlot_Refresh(). Return immediately in that case. */
+    if (slot->isPresentThread == PR_GetCurrentThread()) {
+        return PR_TRUE;
+    }
     /* Set the delay time for checking the token presence */
     if (s_token_delay_time == 0) {
         s_token_delay_time = PR_SecondsToInterval(NSSSLOT_TOKEN_DELAY_TIME);
@@ -130,7 +136,7 @@ nssSlot_IsTokenPresent(
 
     /* avoid repeated calls to check token status within set interval */
     PZ_Lock(slot->isPresentLock);
-    if (within_token_delay_period(slot)) {
+    if (token_status_checked(slot)) {
         CK_FLAGS ckFlags = slot->ckFlags;
         PZ_Unlock(slot->isPresentLock);
         return ((ckFlags & CKF_TOKEN_PRESENT) != 0);
@@ -146,12 +152,12 @@ nssSlot_IsTokenPresent(
 
     /* set up condition so only one thread is active in this part of the code at a time */
     PZ_Lock(slot->isPresentLock);
-    while (slot->inIsPresent) {
+    while (slot->isPresentThread) {
         PR_WaitCondVar(slot->isPresentCondition, 0);
     }
     /* if we were one of multiple threads here, the first thread will have
      * given us the answer, no need to make more queries of the token. */
-    if (within_token_delay_period(slot)) {
+    if (token_status_checked(slot)) {
         CK_FLAGS ckFlags = slot->ckFlags;
         PZ_Unlock(slot->isPresentLock);
         return ((ckFlags & CKF_TOKEN_PRESENT) != 0);
@@ -159,7 +165,7 @@ nssSlot_IsTokenPresent(
     /* this is the winning thread, block all others until we've determined
      * if the token is present and that it needs initialization. */
     slot->lastTokenPingState = nssSlotLastPingState_Update;
-    slot->inIsPresent = PR_TRUE;
+    slot->isPresentThread = PR_GetCurrentThread();
 
     PZ_Unlock(slot->isPresentLock);
 
@@ -257,7 +263,7 @@ done:
         slot->lastTokenPingTime = PR_IntervalNow();
         slot->lastTokenPingState = nssSlotLastPingState_Valid;
     }
-    slot->inIsPresent = PR_FALSE;
+    slot->isPresentThread = NULL;
     PR_NotifyAllCondVar(slot->isPresentCondition);
     PZ_Unlock(slot->isPresentLock);
     return isPresent;
diff --git a/lib/dev/devt.h b/lib/dev/devt.h
index 268cc9e07..0f6d9e49a 100644
--- a/lib/dev/devt.h
+++ b/lib/dev/devt.h
@@ -92,7 +92,7 @@ struct NSSSlotStr {
     PK11SlotInfo *pk11slot;
     PZLock *isPresentLock;
     PRCondVar *isPresentCondition;
-    PRBool inIsPresent;
+    PRThread *isPresentThread;
 };
 
 struct nssSessionStr {