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Commit 0cfcfac1 authored by Bart Van Assche's avatar Bart Van Assche
Browse files

libhealthloop: Handle netlink receive buffer overflows 



The Linux kernel netlink implementation sets EPOLLERR if delivery of a
netlink message fails because of a buffer overrun (see also the Linux
kernel netlink_overrun() and sock_def_error_report() functions). Handle
buffer overruns by calling ScheduleBatteryUpdate() unconditionally.

Bug: 203462310
Change-Id: I54f7d239e6b4caad0db4d1b15de7c0385f796ebd
Signed-off-by: default avatarBart Van Assche <bvanassche@google.com>
parent 6fe3618e

health/utils/libhealthloop/HealthLoop.cpp

+11 −6
Original line number Diff line number Diff line
@@ -57,14 +57,13 @@ int HealthLoop::RegisterEvent(int fd, BoundFunction func, EventWakeup wakeup) { 
                                          EventHandler{this, fd, std::move(func)}))

                                  .get();



    struct epoll_event ev;



    ev.events = EPOLLIN;

    struct epoll_event ev = {

            .events = EPOLLIN | EPOLLERR,

            .data.ptr = reinterpret_cast<void*>(event_handler),

    };



    if (wakeup == EVENT_WAKEUP_FD) ev.events |= EPOLLWAKEUP;



    ev.data.ptr = reinterpret_cast<void*>(event_handler);



    if (epoll_ctl(epollfd_, EPOLL_CTL_ADD, fd, &ev) == -1) {

        KLOG_ERROR(LOG_TAG, "epoll_ctl failed; errno=%d\n", errno);

        return -1;
@@ -119,9 +118,15 @@ void HealthLoop::PeriodicChores() { 


// TODO(b/140330870): Use BPF instead.

#define UEVENT_MSG_LEN 2048

void HealthLoop::UeventEvent(uint32_t /*epevents*/) {

void HealthLoop::UeventEvent(uint32_t epevents) {

    // No need to lock because uevent_fd_ is guaranteed to be initialized.



    if (epevents & EPOLLERR) {

        // The netlink receive buffer overflowed.

        ScheduleBatteryUpdate();

        return;

    }



    char msg[UEVENT_MSG_LEN + 2];

    char* cp;

    int n;