[timer] fix elapsed overflow (#3789)

This commit fixes a bug in the commissioner when a joiner's expiration
time has alerady elapsed.

This commit also introduces convenience methods for computing time
elapsed and diffs.

src/cli/cli.cpp

@@ -2011,7 +2011,7 @@ void Interpreter::HandleIcmpReceive(Message &               aMessage,
 
     if (aMessage.Read(aMessage.GetOffset(), sizeof(uint32_t), &timestamp) >= static_cast<int>(sizeof(uint32_t)))
     {
-        mServer->OutputFormat(" time=%dms", TimerMilli::GetNow() - HostSwap32(timestamp));
+        mServer->OutputFormat(" time=%dms", TimerMilli::Elapsed(HostSwap32(timestamp)));
     }
 
     mServer->OutputFormat("\r\n");

src/core/api/thread_api.cpp

@@ -360,8 +360,8 @@ otError otThreadGetParentInfo(otInstance *aInstance, otRouterInfo *aParentInfo)
     aParentInfo->mPathCost       = parent->GetCost();
     aParentInfo->mLinkQualityIn  = parent->GetLinkInfo().GetLinkQuality();
     aParentInfo->mLinkQualityOut = parent->GetLinkQualityOut();
-    aParentInfo->mAge = static_cast<uint8_t>(TimerMilli::MsecToSec(TimerMilli::GetNow() - parent->GetLastHeard()));
-    aParentInfo->mAllocated       = true;
+    aParentInfo->mAge       = static_cast<uint8_t>(TimerMilli::MsecToSec(TimerMilli::Elapsed(parent->GetLastHeard())));
+    aParentInfo->mAllocated = true;
     aParentInfo->mLinkEstablished = parent->GetState() == Neighbor::kStateValid;
 
 exit:

src/core/coap/coap.cpp

@@ -263,7 +263,7 @@ void CoapBase::HandleRetransmissionTimer(Timer &aTimer)
 void CoapBase::HandleRetransmissionTimer(void)
 {
     uint32_t         now       = TimerMilli::GetNow();
-    uint32_t         nextDelta = 0xffffffff;
+    uint32_t         nextDelta = TimerMilli::kForeverDt;
     CoapMetadata     coapMetadata;
     Message *        message     = static_cast<Message *>(mPendingRequests.GetHead());
     Message *        nextMessage = NULL;
@@ -276,10 +276,11 @@ void CoapBase::HandleRetransmissionTimer(void)
 
         if (coapMetadata.IsLater(now))
         {
+            uint32_t diff = TimerMilli::Elapsed(now, coapMetadata.mNextTimerShot);
             // Calculate the next delay and choose the lowest.
-            if (coapMetadata.mNextTimerShot - now < nextDelta)
+            if (diff < nextDelta)
             {
-                nextDelta = coapMetadata.mNextTimerShot - now;
+                nextDelta = diff;
             }
         }
         else if ((coapMetadata.mConfirmable) && (coapMetadata.mRetransmissionCount < kMaxRetransmit))
@@ -316,7 +317,7 @@ void CoapBase::HandleRetransmissionTimer(void)
         message = nextMessage;
     }
 
-    if (nextDelta != 0xffffffff)
+    if (nextDelta != TimerMilli::kForeverDt)
     {
         mRetransmissionTimer.Start(nextDelta);
     }

src/core/common/timer.hpp

@@ -37,6 +37,7 @@
 #include "openthread-core-config.h"
 
 #include <stddef.h>
+
 #include "utils/wrap_stdint.h"
 
 #include <openthread/platform/alarm-micro.h>
@@ -69,10 +70,9 @@ class Timer : public InstanceLocator, public OwnerLocator
     friend class TimerScheduler;
 
 public:
-    enum
-    {
-        kMaxDt = (1UL << 31) - 1, //< Maximum permitted value for parameter `aDt` in `Start` and `StartAt` method.
-    };
+    static const uint32_t kMaxDt =
+        (1UL << 31) - 1; ///< Maximum permitted value for parameter `aDt` in `Start` and `StartAt` method.
+    static const uint32_t kForeverDt = 0xffffffff; ///< The special forever `aDt` value.
 
     /**
      * This function pointer is called when the timer expires.
@@ -181,6 +181,46 @@ public:
      */
     void Stop(void);
 
+    /**
+     * This static method returns the time diff in milliseconds between @p aStart and @p aEnd.
+     *
+     * @param[in]   aStart  The start time.
+     * @param[in]   aEnd    The end time.
+     *
+     * @returns The time diff in milliseconds.
+     *
+     */
+    static int32_t Diff(uint32_t aStart, uint32_t aEnd)
+    {
+        uint32_t diff = aEnd - aStart;
+        return reinterpret_cast<int32_t &>(diff);
+    }
+
+    /**
+     * This static method returns the time elapsed in milliseconds from @p aStart to @p aEnd.
+     *
+     * @note This method assumes @p aEnd is after @p aStart.
+     *
+     * @param[in]   aStart  The start time.
+     * @param[in]   aEnd    The end time.
+     *
+     * @returns The elapsed time in milliseconds.
+     *
+     */
+    static uint32_t Elapsed(uint32_t aStart, uint32_t aEnd) { return aEnd - aStart; }
+
+    /**
+     * This static method returns the time passed in milliseconds since @p aStart.
+     *
+     * @note This method assumes now is after @p aStart.
+     *
+     * @param[in]   aStart  The start time.
+     *
+     * @returns The elapsed time in milliseconds.
+     *
+     */
+    static uint32_t Elapsed(uint32_t aStart) { return Elapsed(aStart, GetNow()); }
+
     /**
      * This static method returns the current time in milliseconds.
      *

src/core/meshcop/commissioner.cpp

@@ -399,25 +399,31 @@ void Commissioner::HandleJoinerExpirationTimer(void)
 void Commissioner::UpdateJoinerExpirationTimer(void)
 {
     uint32_t now         = TimerMilli::GetNow();
-    uint32_t nextTimeout = 0xffffffff;
+    uint32_t nextTimeout = TimerMilli::kForeverDt;
 
     // Check if timer should be set for next Joiner.
     for (size_t i = 0; i < OT_ARRAY_LENGTH(mJoiners); i++)
     {
-        {
-            if (!mJoiners[i].mValid)
-            {
-                continue;
-            }
+        int32_t diff;
 
-            if (mJoiners[i].mExpirationTime - now < nextTimeout)
-            {
-                nextTimeout = mJoiners[i].mExpirationTime - now;
-            }
+        if (!mJoiners[i].mValid)
+        {
+            continue;
+        }
+
+        diff = TimerMilli::Diff(now, mJoiners[i].mExpirationTime);
+        if (diff <= 0)
+        {
+            nextTimeout = 0;
+            break;
+        }
+        else if (static_cast<uint32_t>(diff) < nextTimeout)
+        {
+            nextTimeout = static_cast<uint32_t>(diff);
         }
     }
 
-    if (nextTimeout != 0xffffffff)
+    if (nextTimeout != TimerMilli::kForeverDt)
     {
         // Update the timer to the timeout of the next Joiner.
         mJoinerExpirationTimer.Start(nextTimeout);

src/core/meshcop/dataset.cpp

@@ -479,7 +479,7 @@ otError Dataset::AppendMleDatasetTlv(Message &aMessage) const
         }
         else if (cur->GetType() == Tlv::kDelayTimer)
         {
-            uint32_t      elapsed = TimerMilli::GetNow() - mUpdateTime;
+            uint32_t      elapsed = TimerMilli::Elapsed(mUpdateTime);
             DelayTimerTlv delayTimer(static_cast<const DelayTimerTlv &>(*cur));
 
             if (delayTimer.GetDelayTimer() > elapsed)

src/core/meshcop/dataset_local.cpp

@@ -109,7 +109,7 @@ otError DatasetLocal::Read(Dataset &aDataset) const
         delayTimer = static_cast<DelayTimerTlv *>(aDataset.Get(Tlv::kDelayTimer));
         VerifyOrExit(delayTimer);
 
-        elapsed = TimerMilli::GetNow() - mUpdateTime;
+        elapsed = TimerMilli::Elapsed(mUpdateTime);
 
         if (delayTimer->GetDelayTimer() > elapsed)
         {

src/core/net/dhcp6_client.cpp

@@ -315,7 +315,7 @@ otError Dhcp6Client::AppendElapsedTime(Message &aMessage)
     ElapsedTime option;
 
     option.Init();
-    option.SetElapsedTime(static_cast<uint16_t>(TimerMilli::MsecToSec(TimerMilli::GetNow() - mStartTime)));
+    option.SetElapsedTime(static_cast<uint16_t>(TimerMilli::MsecToSec(TimerMilli::Elapsed(mStartTime))));
     return aMessage.Append(&option, sizeof(option));
 }
 

src/core/net/dns_client.cpp

@@ -395,7 +395,7 @@ void Client::HandleRetransmissionTimer(Timer &aTimer)
 void Client::HandleRetransmissionTimer(void)
 {
     uint32_t         now       = TimerMilli::GetNow();
-    uint32_t         nextDelta = 0xffffffff;
+    uint32_t         nextDelta = TimerMilli::kForeverDt;
     QueryMetadata    queryMetadata;
     Message *        message     = mPendingQueries.GetHead();
     Message *        nextMessage = NULL;
@@ -408,21 +408,27 @@ void Client::HandleRetransmissionTimer(void)
 
         if (queryMetadata.IsLater(now))
         {
+            uint32_t diff = TimerMilli::Elapsed(now, queryMetadata.mTransmissionTime);
+
             // Calculate the next delay and choose the lowest.
-            if (queryMetadata.mTransmissionTime - now < nextDelta)
+            if (diff < nextDelta)
             {
-                nextDelta = queryMetadata.mTransmissionTime - now;
+                nextDelta = diff;
             }
         }
         else if (queryMetadata.mRetransmissionCount < kMaxRetransmit)
         {
+            uint32_t diff;
+
             // Increment retransmission counter and timer.
             queryMetadata.mRetransmissionCount++;
             queryMetadata.mTransmissionTime = now + kResponseTimeout;
             queryMetadata.UpdateIn(*message);
 
+            diff = TimerMilli::Elapsed(now, queryMetadata.mTransmissionTime);
+
             // Check if retransmission time is lower than current lowest.
-            if (queryMetadata.mTransmissionTime - now < nextDelta)
+            if (diff < nextDelta)
             {
                 nextDelta = queryMetadata.mTransmissionTime - now;
             }
@@ -443,7 +449,7 @@ void Client::HandleRetransmissionTimer(void)
         message = nextMessage;
     }
 
-    if (nextDelta != 0xffffffff)
+    if (nextDelta != TimerMilli::kForeverDt)
     {
         mRetransmissionTimer.Start(nextDelta);
     }

src/core/net/ip6_mpl.cpp

@@ -334,7 +334,7 @@ void Mpl::HandleRetransmissionTimer(Timer &aTimer)
 void Mpl::HandleRetransmissionTimer(void)
 {
     uint32_t                   now       = TimerMilli::GetNow();
-    uint32_t                   nextDelta = 0xffffffff;
+    uint32_t                   nextDelta = TimerMilli::kForeverDt;
     MplBufferedMessageMetadata messageMetadata;
 
     Message *message     = mBufferedMessageSet.GetHead();
@@ -347,10 +347,12 @@ void Mpl::HandleRetransmissionTimer(void)
 
         if (messageMetadata.IsLater(now))
         {
+            uint32_t diff = TimerMilli::Elapsed(now, messageMetadata.GetTransmissionTime());
+
             // Calculate the next retransmission time and choose the lowest.
-            if (messageMetadata.GetTransmissionTime() - now < nextDelta)
+            if (diff < nextDelta)
             {
-                nextDelta = messageMetadata.GetTransmissionTime() - now;
+                nextDelta = diff;
             }
         }
         else
@@ -360,6 +362,8 @@ void Mpl::HandleRetransmissionTimer(void)
 
             if (messageMetadata.GetTransmissionCount() < GetTimerExpirations())
             {
+                uint32_t diff;
+
                 Message *messageCopy = message->Clone(message->GetLength() - sizeof(MplBufferedMessageMetadata));
 
                 if (messageCopy != NULL)
@@ -375,10 +379,12 @@ void Mpl::HandleRetransmissionTimer(void)
                 messageMetadata.GenerateNextTransmissionTime(now, kDataMessageInterval);
                 messageMetadata.UpdateIn(*message);
 
+                diff = TimerMilli::Elapsed(now, messageMetadata.GetTransmissionTime());
+
                 // Check if retransmission time is lower than the current lowest one.
-                if (messageMetadata.GetTransmissionTime() - now < nextDelta)
+                if (diff < nextDelta)
                 {
-                    nextDelta = messageMetadata.GetTransmissionTime() - now;
+                    nextDelta = diff;
                 }
             }
             else
@@ -407,7 +413,7 @@ void Mpl::HandleRetransmissionTimer(void)
         message = nextMessage;
     }
 
-    if (nextDelta != 0xffffffff)
+    if (nextDelta != TimerMilli::kForeverDt)
     {
         mRetransmissionTimer.Start(nextDelta);
     }

src/core/net/sntp_client.cpp

@@ -269,7 +269,7 @@ void Client::HandleRetransmissionTimer(Timer &aTimer)
 void Client::HandleRetransmissionTimer(void)
 {
     uint32_t         now       = TimerMilli::GetNow();
-    uint32_t         nextDelta = 0xffffffff;
+    uint32_t         nextDelta = TimerMilli::kForeverDt;
     QueryMetadata    queryMetadata;
     Message *        message     = mPendingQueries.GetHead();
     Message *        nextMessage = NULL;
@@ -282,23 +282,29 @@ void Client::HandleRetransmissionTimer(void)
 
         if (queryMetadata.IsLater(now))
         {
+            uint32_t diff = TimerMilli::Elapsed(now, queryMetadata.mTransmissionTime);
+
             // Calculate the next delay and choose the lowest.
-            if (queryMetadata.mTransmissionTime - now < nextDelta)
+            if (diff < nextDelta)
             {
-                nextDelta = queryMetadata.mTransmissionTime - now;
+                nextDelta = diff;
             }
         }
         else if (queryMetadata.mRetransmissionCount < kMaxRetransmit)
         {
+            uint32_t diff;
+
             // Increment retransmission counter and timer.
             queryMetadata.mRetransmissionCount++;
             queryMetadata.mTransmissionTime = now + kResponseTimeout;
             queryMetadata.UpdateIn(*message);
 
+            diff = TimerMilli::Elapsed(now, queryMetadata.mTransmissionTime);
+
             // Check if retransmission time is lower than current lowest.
-            if (queryMetadata.mTransmissionTime - now < nextDelta)
+            if (diff < nextDelta)
             {
-                nextDelta = queryMetadata.mTransmissionTime - now;
+                nextDelta = diff;
             }
 
             // Retransmit
@@ -317,7 +323,7 @@ void Client::HandleRetransmissionTimer(void)
         message = nextMessage;
     }
 
-    if (nextDelta != 0xffffffff)
+    if (nextDelta != TimerMilli::kForeverDt)
     {
         mRetransmissionTimer.Start(nextDelta);
     }

src/core/thread/address_resolver.cpp

@@ -622,7 +622,7 @@ void AddressResolver::HandleAddressQuery(Coap::Message &aMessage, const Ip6::Mes
         if (child.HasIp6Address(GetInstance(), targetTlv.GetTarget()))
         {
             mlIidTlv.SetIid(child.GetExtAddress());
-            lastTransactionTimeTlv.SetTime(TimerMilli::GetNow() - child.GetLastHeard());
+            lastTransactionTimeTlv.SetTime(TimerMilli::Elapsed(child.GetLastHeard()));
             SendAddressQueryResponse(targetTlv, mlIidTlv, &lastTransactionTimeTlv, aMessageInfo.GetPeerAddr());
             ExitNow();
         }

src/core/thread/mle.cpp

@@ -1816,7 +1816,7 @@ void Mle::HandleDelayedResponseTimer(void)
 {
     DelayedResponseHeader delayedResponse;
     uint32_t              now         = TimerMilli::GetNow();
-    uint32_t              nextDelay   = 0xffffffff;
+    uint32_t              nextDelay   = TimerMilli::kForeverDt;
     Message *             message     = mDelayedResponses.GetHead();
     Message *             nextMessage = NULL;
 
@@ -1864,7 +1864,7 @@ void Mle::HandleDelayedResponseTimer(void)
         message = nextMessage;
     }
 
-    if (nextDelay != 0xffffffff)
+    if (nextDelay != TimerMilli::kForeverDt)
     {
         mDelayedResponseTimer.Start(nextDelay);
     }
@@ -3953,7 +3953,7 @@ void Mle::HandleParentSearchTimer(void)
         // from `UpdateParentSearchState()`. We want to limit this to happen
         // only once within a backoff interval.
 
-        if (TimerMilli::GetNow() - mParentSearchBackoffCancelTime >= kParentSearchBackoffInterval)
+        if (TimerMilli::Elapsed(mParentSearchBackoffCancelTime) >= kParentSearchBackoffInterval)
         {
             mParentSearchBackoffWasCanceled = false;
             otLogInfoMle("PeriodicParentSearch: Backoff cancellation is allowed on parent switch");

src/core/thread/mle_router.cpp

@@ -1649,7 +1649,7 @@ otError MleRouter::HandleParentRequest(const Message &aMessage, const Ip6::Messa
         }
 #endif
     }
-    else if ((TimerMilli::GetNow() - child->GetLastHeard()) < kParentRequestRouterTimeout)
+    else if (TimerMilli::Elapsed(child->GetLastHeard()) < kParentRequestRouterTimeout)
     {
         ExitNow(error = OT_ERROR_DUPLICATED);
     }
@@ -1790,7 +1790,7 @@ void MleRouter::HandleStateUpdateTimer(void)
             break;
         }
 
-        if ((TimerMilli::GetNow() - child.GetLastHeard()) >= timeout)
+        if (TimerMilli::Elapsed(child.GetLastHeard()) >= timeout)
         {
             otLogInfoMle("Child timeout expired");
             RemoveNeighbor(child);
@@ -1814,7 +1814,7 @@ void MleRouter::HandleStateUpdateTimer(void)
             continue;
         }
 
-        age = TimerMilli::GetNow() - router.GetLastHeard();
+        age = TimerMilli::Elapsed(router.GetLastHeard());
 
         if (router.GetState() == Neighbor::kStateValid)
         {
@@ -3609,7 +3609,7 @@ otError MleRouter::GetChildInfo(Child &aChild, otChildInfo &aChildInfo)
     aChildInfo.mRloc16             = aChild.GetRloc16();
     aChildInfo.mChildId            = GetChildId(aChild.GetRloc16());
     aChildInfo.mNetworkDataVersion = aChild.GetNetworkDataVersion();
-    aChildInfo.mAge                = TimerMilli::MsecToSec(TimerMilli::GetNow() - aChild.GetLastHeard());
+    aChildInfo.mAge                = TimerMilli::MsecToSec(TimerMilli::Elapsed(aChild.GetLastHeard()));
     aChildInfo.mLinkQualityIn      = aChild.GetLinkInfo().GetLinkQuality();
     aChildInfo.mAverageRssi        = aChild.GetLinkInfo().GetAverageRss();
     aChildInfo.mLastRssi           = aChild.GetLinkInfo().GetLastRss();
@@ -3687,7 +3687,7 @@ exit:
     if (neighbor != NULL)
     {
         aNeighInfo.mExtAddress       = neighbor->GetExtAddress();
-        aNeighInfo.mAge              = TimerMilli::MsecToSec(TimerMilli::GetNow() - neighbor->GetLastHeard());
+        aNeighInfo.mAge              = TimerMilli::MsecToSec(TimerMilli::Elapsed(neighbor->GetLastHeard()));
         aNeighInfo.mRloc16           = neighbor->GetRloc16();
         aNeighInfo.mLinkFrameCounter = neighbor->GetLinkFrameCounter();
         aNeighInfo.mMleFrameCounter  = neighbor->GetMleFrameCounter();

src/core/thread/network_data.cpp

@@ -1000,8 +1000,7 @@ otError NetworkData::SendServerDataNotification(uint16_t aRloc16)
     Coap::Message *  message = NULL;
     Ip6::MessageInfo messageInfo;
 
-    VerifyOrExit(!mLastAttemptWait || static_cast<int32_t>(TimerMilli::GetNow() - mLastAttempt) < kDataResubmitDelay,
-                 error = OT_ERROR_ALREADY);
+    VerifyOrExit(!mLastAttemptWait || TimerMilli::Elapsed(mLastAttempt) < kDataResubmitDelay, error = OT_ERROR_ALREADY);
 
     VerifyOrExit((message = Get<Coap::Coap>().NewMessage()) != NULL, error = OT_ERROR_NO_BUFS);
 

src/core/thread/network_data_leader_ftd.cpp

@@ -1575,7 +1575,7 @@ void Leader::HandleTimer(void)
             continue;
         }
 
-        if ((TimerMilli::GetNow() - mContextLastUsed[i]) >= TimerMilli::SecToMsec(mContextIdReuseDelay))
+        if (TimerMilli::Elapsed(mContextLastUsed[i]) >= TimerMilli::SecToMsec(mContextIdReuseDelay))
         {
             FreeContext(kMinContextId + i);
         }

src/core/thread/router_table.cpp

@@ -436,7 +436,7 @@ otError RouterTable::GetRouterInfo(uint16_t aRouterId, otRouterInfo &aRouterInfo
     aRouterInfo.mPathCost        = router->GetCost();
     aRouterInfo.mLinkQualityIn   = router->GetLinkInfo().GetLinkQuality();
     aRouterInfo.mLinkQualityOut  = router->GetLinkQualityOut();
-    aRouterInfo.mAge = static_cast<uint8_t>(TimerMilli::MsecToSec(TimerMilli::GetNow() - router->GetLastHeard()));
+    aRouterInfo.mAge = static_cast<uint8_t>(TimerMilli::MsecToSec(TimerMilli::Elapsed(router->GetLastHeard())));
 
 exit:
     return error;
@@ -449,7 +449,7 @@ Router *RouterTable::GetLeader(void)
 
 uint32_t RouterTable::GetLeaderAge(void) const
 {
-    return (mActiveRouterCount > 0) ? TimerMilli::MsecToSec(TimerMilli::GetNow() - mRouterIdSequenceLastUpdated)
+    return (mActiveRouterCount > 0) ? TimerMilli::MsecToSec(TimerMilli::Elapsed(mRouterIdSequenceLastUpdated))
                                     : 0xffffffff;
 }
 

src/core/thread/time_sync_service.cpp

@@ -66,6 +66,7 @@ TimeSync::TimeSync(Instance &aInstance)
     , mTimer(aInstance, HandleTimeout, this)
     , mCurrentStatus(OT_NETWORK_TIME_UNSYNCHRONIZED)
 {
+    mLastTimeSyncReceived = TimerMilli::GetNow();
     CheckAndHandleChanges(false);
 }
 
@@ -133,7 +134,7 @@ void TimeSync::NotifyTimeSyncCallback(void)
 void TimeSync::ProcessTimeSync(void)
 {
     if (Get<Mle::MleRouter>().GetRole() == OT_DEVICE_ROLE_LEADER &&
-        TimerMilli::GetNow() - mLastTimeSyncSent > TimerMilli::SecToMsec(mTimeSyncPeriod))
+        TimerMilli::Elapsed(mLastTimeSyncSent) > TimerMilli::SecToMsec(mTimeSyncPeriod))
     {
         IncrementTimeSyncSeq();
         mTimeSyncRequired = true;
@@ -180,7 +181,7 @@ void TimeSync::CheckAndHandleChanges(bool aTimeUpdated)
     otNetworkTimeStatus networkTimeStatus       = OT_NETWORK_TIME_SYNCHRONIZED;
     const otDeviceRole  role                    = Get<Mle::MleRouter>().GetRole();
     const uint32_t      resyncNeededThresholdMs = 2 * TimerMilli::SecToMsec(mTimeSyncPeriod);
-    const uint32_t      timeSyncLastSyncMs      = TimerMilli::GetNow() - mLastTimeSyncReceived;
+    const uint32_t      timeSyncLastSyncMs      = TimerMilli::Elapsed(mLastTimeSyncReceived);
 
     mTimer.Stop();
 

src/core/utils/jam_detector.cpp

@@ -208,7 +208,7 @@ exit:
 
 void JamDetector::UpdateHistory(bool aDidExceedThreshold)
 {
-    uint32_t now = TimerMilli::GetNow();
+    int32_t diff = TimerMilli::Diff(mCurSecondStartTime, TimerMilli::GetNow());
 
     // If the RSSI is ever below the threshold, update mAlwaysAboveThreshold
     // for current second interval.
@@ -218,7 +218,7 @@ void JamDetector::UpdateHistory(bool aDidExceedThreshold)
     }
 
     // If we reached end of current one second interval, update the history bitmap
-    if (now - mCurSecondStartTime >= kOneSecondInterval)
+    if (diff >= kOneSecondInterval)
     {
         mHistoryBitmap <<= 1;
 
@@ -229,10 +229,7 @@ void JamDetector::UpdateHistory(bool aDidExceedThreshold)
 
         mAlwaysAboveThreshold = true;
 
-        while (now - mCurSecondStartTime >= kOneSecondInterval)
-        {
-            mCurSecondStartTime += kOneSecondInterval;
-        }
+        mCurSecondStartTime += (static_cast<uint32_t>(diff) / kOneSecondInterval) * kOneSecondInterval;
 
         UpdateJamState();
     }