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Commit a3be9966 authored by Nikita Ioffe's avatar Nikita Ioffe
Browse files

Cleanup logic in KillZramBackingDevice 

Since this function is used in userspace reboot, we need to be more
diligent with error handling, e.g.:

* If init fails to read /sys/block/zram0/backing_dev, then fail and
fallback to hard reboot.
* Always call swapoff.
* Always reset zram.
* Tear down loop device only if zram is backed by a loop device.

Test: adb reboot userspace
Bug: 153917129
Change-Id: I4709da1d08cf427ad9c898cfb2506b6a29f1d680
Merged-In: I4709da1d08cf427ad9c898cfb2506b6a29f1d680
(cherry picked from commit a840d405)
parent 10f8f5e3

init/reboot.cpp

+14 −4
Original line number Original line Diff line number Diff line
@@ -203,6 +203,7 @@ static void TurnOffBacklight() { 
}

}





static Result<void> CallVdc(const std::string& system, const std::string& cmd) {

static Result<void> CallVdc(const std::string& system, const std::string& cmd) {

    LOG(INFO) << "Calling /system/bin/vdc " << system << " " << cmd;

    const char* vdc_argv[] = {"/system/bin/vdc", system.c_str(), cmd.c_str()};

    const char* vdc_argv[] = {"/system/bin/vdc", system.c_str(), cmd.c_str()};

    int status;

    int status;

    if (logwrap_fork_execvp(arraysize(vdc_argv), vdc_argv, &status, false, LOG_KLOG, true,

    if (logwrap_fork_execvp(arraysize(vdc_argv), vdc_argv, &status, false, LOG_KLOG, true,
@@ -456,10 +457,14 @@ static UmountStat TryUmountAndFsck(unsigned int cmd, bool run_fsck, 
#define ZRAM_RESET    "/sys/block/zram0/reset"

#define ZRAM_RESET    "/sys/block/zram0/reset"

#define ZRAM_BACK_DEV "/sys/block/zram0/backing_dev"

#define ZRAM_BACK_DEV "/sys/block/zram0/backing_dev"

static Result<void> KillZramBackingDevice() {

static Result<void> KillZramBackingDevice() {

    if (access(ZRAM_BACK_DEV, F_OK) != 0 && errno == ENOENT) {

        LOG(INFO) << "No zram backing device configured";

        return {};

    }

    std::string backing_dev;

    std::string backing_dev;

    if (!android::base::ReadFileToString(ZRAM_BACK_DEV, &backing_dev)) return {};

    if (!android::base::ReadFileToString(ZRAM_BACK_DEV, &backing_dev)) {



        return ErrnoError() << "Failed to read " << ZRAM_BACK_DEV;

    if (!android::base::StartsWith(backing_dev, "/dev/block/loop")) return {};

    }





    // cut the last "\n"

    // cut the last "\n"

    backing_dev.erase(backing_dev.length() - 1);

    backing_dev.erase(backing_dev.length() - 1);
@@ -478,6 +483,11 @@ static Result<void> KillZramBackingDevice() { 
                       << " failed";

                       << " failed";

    }

    }





    if (!android::base::StartsWith(backing_dev, "/dev/block/loop")) {

        LOG(INFO) << backing_dev << " is not a loop device. Exiting early";

        return {};

    }



    // clear loopback device

    // clear loopback device

    unique_fd loop(TEMP_FAILURE_RETRY(open(backing_dev.c_str(), O_RDWR | O_CLOEXEC)));

    unique_fd loop(TEMP_FAILURE_RETRY(open(backing_dev.c_str(), O_RDWR | O_CLOEXEC)));

    if (loop.get() < 0) {

    if (loop.get() < 0) {