From 67df85ea36fe90d199d5782df925f6b71deffbe0 Mon Sep 17 00:00:00 2001 From: Junyu Lai Date: Fri, 30 Jul 2021 02:31:26 +0000 Subject: [PATCH] Fix mMobileIfaces is not protected by lock Currently, mMobileIfaces is accessed from multiple threads, and should be protected from concurrent accessing. However, since the variable could be accessed frequently, holding the mStatsLock would make this be blocked by network stats I/O operations. Thus, protect the variable by making it volatile. Test: Wifi on/off stress test Bug: 192758557 Original-Change: https://android-review.googlesource.com/1765686 Merged-In: Ie7694a63f5203ee7c83830ca13d97219b7949fd7 Change-Id: Ie7694a63f5203ee7c83830ca13d97219b7949fd7 --- .../server/net/NetworkStatsService.java | 20 ++++++++++++++----- 1 file changed, 15 insertions(+), 5 deletions(-) diff --git a/services/core/java/com/android/server/net/NetworkStatsService.java b/services/core/java/com/android/server/net/NetworkStatsService.java index 4ee867b7d0..097b0711ef 100644 --- a/services/core/java/com/android/server/net/NetworkStatsService.java +++ b/services/core/java/com/android/server/net/NetworkStatsService.java @@ -289,8 +289,7 @@ public class NetworkStatsService extends INetworkStatsService.Stub { private String mActiveIface; /** Set of any ifaces associated with mobile networks since boot. */ - @GuardedBy("mStatsLock") - private String[] mMobileIfaces = new String[0]; + private volatile String[] mMobileIfaces = new String[0]; /** Set of all ifaces currently used by traffic that does not explicitly specify a Network. */ @GuardedBy("mStatsLock") @@ -935,7 +934,12 @@ public class NetworkStatsService extends INetworkStatsService.Stub { @Override public String[] getMobileIfaces() { - return mMobileIfaces; + // TODO (b/192758557): Remove debug log. + if (ArrayUtils.contains(mMobileIfaces, null)) { + throw new NullPointerException( + "null element in mMobileIfaces: " + Arrays.toString(mMobileIfaces)); + } + return mMobileIfaces.clone(); } @Override @@ -1084,7 +1088,8 @@ public class NetworkStatsService extends INetworkStatsService.Stub { } @Override - public long getIfaceStats(String iface, int type) { + public long getIfaceStats(@NonNull String iface, int type) { + Objects.requireNonNull(iface); long nativeIfaceStats = nativeGetIfaceStat(iface, type, checkBpfStatsEnable()); if (nativeIfaceStats == -1) { return nativeIfaceStats; @@ -1382,7 +1387,12 @@ public class NetworkStatsService extends INetworkStatsService.Stub { } } - mMobileIfaces = mobileIfaces.toArray(new String[mobileIfaces.size()]); + mMobileIfaces = mobileIfaces.toArray(new String[0]); + // TODO (b/192758557): Remove debug log. + if (ArrayUtils.contains(mMobileIfaces, null)) { + throw new NullPointerException( + "null element in mMobileIfaces: " + Arrays.toString(mMobileIfaces)); + } } private static int getSubIdForMobile(@NonNull NetworkStateSnapshot state) {