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Commit 525fa6de authored by Nathan Harold's avatar Nathan Harold
Browse files

Guard mIsPendingCellInfoRequest with synch block 

In the event of a modem timeout, there is an instance of
mIsPendingCellInfoRequest that isn't guarded by a sync
block. Due to the behavior of the system, I'm unable to
figure out whether this is actually a problem, though it's
theoretically possible to have it drop a response in the
event that the cache doesn't sync between the time of a
request and a timeout. Becuase it's safe to guard, and
because it's documented to be guarded by
mPendingCellInfoRequests, adding a sync block for safety.

Bug: 145965248
Test: manual
Change-Id: I1ca570011c8689a55b8bbbd39cda2e17338a5ac7
parent f00698cb

src/java/com/android/internal/telephony/ServiceStateTracker.java

+17 −13
Original line number Diff line number Diff line
@@ -1141,21 +1141,25 @@ public class ServiceStateTracker extends Handler { 
                        }

                    }

                } else {

                    synchronized (mPendingCellInfoRequests) {

                        // If we receive an empty message, it's probably a timeout; if there is no

                        // pending request, drop it.

                        if (!mIsPendingCellInfoRequest) break;

                    // If there is a request pending, we still need to check whether it's a timeout

                    // for the current request of whether it's leftover from a previous request.

                        // If there is a request pending, we still need to check whether it's a

                        // timeout for the current request of whether it's leftover from a

                        // previous request.

                        final long curTime = SystemClock.elapsedRealtime();

                        if ((curTime - mLastCellInfoReqTime) <  CELL_INFO_LIST_QUERY_TIMEOUT) {

                            break;

                        }

                    // We've received a legitimate timeout, so something has gone terribly wrong.

                        // We've received a legitimate timeout, so something has gone terribly

                        // wrong.

                        loge("Timeout waiting for CellInfo; (everybody panic)!");

                        mLastCellInfoList = null;

                        // Since the timeout is applicable, fall through and update all synchronous

                        // callers with the failure.

                    }

                }

                synchronized (mPendingCellInfoRequests) {

                    // If we have pending requests, then service them. Note that in case of a

                    // timeout, we send null responses back to the callers.