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Commit 38c735e6 authored by Marco Ballesio's avatar Marco Ballesio
Browse files

llkd: ignore frozen processes 

verify a process frozen state by reading its frezer cgroup value and
don't consider it as loop-locked if frozen.

Bug: 145698592
Test: llkd_unit_test
Test: Manually froze a few processes and waited for llkd timeout, verifying that
      no processes are killed, no reboot or ramdump occur and no llkd events are
      logged.
Change-Id: Iea02cd86dbd1df0e6658d02581aa4bb9b658f107
parent 62f35129

llkd/libllkd.cpp

+22 −6
Original line number Diff line number Diff line
@@ -304,10 +304,13 @@ struct proc { 
    bool cmdlineValid;             // cmdline has been cached

    bool updated;                  // cleared before monitoring pass.

    bool killed;                   // sent a kill to this thread, next panic...

    bool frozen;                   // process is in frozen cgroup.



    void setComm(const char* _comm) { strncpy(comm + 1, _comm, sizeof(comm) - 2); }



    proc(pid_t tid, pid_t pid, pid_t ppid, const char* _comm, int time, char state)

    void setFrozen(bool _frozen) { frozen = _frozen; }



    proc(pid_t tid, pid_t pid, pid_t ppid, const char* _comm, int time, char state, bool frozen)

        : tid(tid),

          schedUpdate(0),

          nrSwitches(0),
@@ -327,7 +330,8 @@ struct proc { 
          exeMissingValid(false),

          cmdlineValid(false),

          updated(true),

          killed(!llkTestWithKill) {

          killed(!llkTestWithKill),

          frozen(frozen) {

        memset(comm, '\0', sizeof(comm));

        setComm(_comm);

    }
@@ -373,6 +377,8 @@ struct proc { 
        return uid;

    }



    bool isFrozen() { return frozen; }



    void reset(void) {  // reset cache, if we detected pid rollover

        uid = -1;

        state = '?';
@@ -592,8 +598,9 @@ void llkTidRemove(pid_t tid) { 
    tids.erase(tid);

}



proc* llkTidAlloc(pid_t tid, pid_t pid, pid_t ppid, const char* comm, int time, char state) {

    auto it = tids.emplace(std::make_pair(tid, proc(tid, pid, ppid, comm, time, state)));

proc* llkTidAlloc(pid_t tid, pid_t pid, pid_t ppid, const char* comm, int time, char state,

                  bool frozen) {

    auto it = tids.emplace(std::make_pair(tid, proc(tid, pid, ppid, comm, time, state, frozen)));

    return &it.first->second;

}
@@ -1039,12 +1046,18 @@ milliseconds llkCheck(bool checkRunning) { 
                continue;

            }



            // Get the process cgroup

            auto cgroup = ReadFile(piddir + "/cgroup");

            auto frozen = cgroup.find(":freezer:/frozen") != std::string::npos;



            auto procp = llkTidLookup(tid);

            if (procp == nullptr) {

                procp = llkTidAlloc(tid, pid, ppid, pdir, utime + stime, state);

                procp = llkTidAlloc(tid, pid, ppid, pdir, utime + stime, state, frozen);

            } else {

                // comm can change ...

                procp->setComm(pdir);

                // frozen can change, too...

                procp->setFrozen(frozen);

                procp->updated = true;

                // pid/ppid/tid wrap?

                if (((procp->update != prevUpdate) && (procp->update != llkUpdate)) ||
@@ -1084,6 +1097,9 @@ milliseconds llkCheck(bool checkRunning) { 
            if ((tid == myTid) || llkSkipPid(tid)) {

                continue;

            }

            if (procp->isFrozen()) {

                break;

            }

            if (llkSkipPpid(ppid)) {

                break;

            }
@@ -1101,7 +1117,7 @@ milliseconds llkCheck(bool checkRunning) { 


            auto pprocp = llkTidLookup(ppid);

            if (pprocp == nullptr) {

                pprocp = llkTidAlloc(ppid, ppid, 0, "", 0, '?');

                pprocp = llkTidAlloc(ppid, ppid, 0, "", 0, '?', false);

            }

            if (pprocp) {

                if (llkSkipPproc(pprocp, procp)) break;