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Commit bd7c8565 authored by Mark Salyzyn's avatar Mark Salyzyn
Browse files

llkd: add ro.llk.sysrq_t 

Allow sysrq stack trace dump to be disabled by ro.llk.sysrq_t.

Default is true if not on a limited memory device ro.config.low_ram.
Value is true if the property value is "eng" and on a userdebug or
eng device, signaled by the ro.debuggable set to 1.

Test: compile
Bug: 118712403
Change-Id: I02e999dc640125b6a08dca10077716e5d006da49
parent bb1256a7

llkd/README.md

+8 −1
Original line number Diff line number Diff line
@@ -89,7 +89,14 @@ Android Properties 
Android Properties llkd respond to (*prop*_ms parms are in milliseconds):



#### ro.config.low_ram

default false, if true do not sysrq t (dump all threads).

device is configured with limited memory.



#### ro.debuggable

device is configured for userdebug or eng build.



#### ro.llk.sysrq_t

default not ro.config.low_ram, or ro.debuggable if property is "eng".

if true do sysrq t (dump all threads).



#### ro.llk.enable

default false, allow live-lock daemon to be enabled.

llkd/include/llkd.h

+2 −0
Original line number Diff line number Diff line
@@ -35,6 +35,8 @@ unsigned llkCheckMilliseconds(void); 
#define LLK_ENABLE_DEFAULT             false /* "eng" and userdebug true */

#define KHT_ENABLE_WRITEABLE_PROPERTY  "khungtask.enable"

#define KHT_ENABLE_PROPERTY            "ro." KHT_ENABLE_WRITEABLE_PROPERTY

#define LLK_ENABLE_SYSRQ_T_PROPERTY    "ro.llk.sysrq_t"

#define LLK_ENABLE_SYSRQ_T_DEFAULT     true

#define LLK_MLOCKALL_PROPERTY          "ro.llk.mlockall"

#define LLK_MLOCKALL_DEFAULT           true

#define LLK_KILLTEST_PROPERTY          "ro.llk.killtest"

llkd/libllkd.cpp

+15 −4
Original line number Diff line number Diff line
@@ -85,6 +85,7 @@ milliseconds llkStateTimeoutMs[llkNumStates]; // timeout override for eac 
milliseconds llkCheckMs;                             // checking interval to inspect any

                                                     // persistent live-locked states

bool llkLowRam;                                      // ro.config.low_ram

bool llkEnableSysrqT = LLK_ENABLE_SYSRQ_T_DEFAULT;   // sysrq stack trace dump

bool khtEnable = LLK_ENABLE_DEFAULT;                 // [khungtaskd] panic

// [khungtaskd] should have a timeout beyond the granularity of llkTimeoutMs.

// Provides a wide angle of margin b/c khtTimeout is also its granularity.
@@ -525,7 +526,7 @@ void llkPanicKernel(bool dump, pid_t tid, const char* state) { 
        android::base::WriteStringToFd("d", sysrqTriggerFd);

        // This can trigger hardware watchdog, that is somewhat _ok_.

        // But useless if pstore configured for <256KB, low ram devices ...

        if (!llkLowRam) {

        if (llkEnableSysrqT) {

            android::base::WriteStringToFd("t", sysrqTriggerFd);

        }

        ::usleep(200000);  // let everything settle
@@ -799,6 +800,7 @@ void llkCheckSchedUpdate(proc* procp, const std::string& piddir) { 


void llkLogConfig(void) {

    LOG(INFO) << "ro.config.low_ram=" << llkFormat(llkLowRam) << "\n"

              << LLK_ENABLE_SYSRQ_T_PROPERTY "=" << llkFormat(llkEnableSysrqT) << "\n"

              << LLK_ENABLE_PROPERTY "=" << llkFormat(llkEnable) << "\n"

              << KHT_ENABLE_PROPERTY "=" << llkFormat(khtEnable) << "\n"

              << LLK_MLOCKALL_PROPERTY "=" << llkFormat(llkMlockall) << "\n"
@@ -1150,13 +1152,22 @@ unsigned llkCheckMilliseconds() { 
    return duration_cast<milliseconds>(llkCheck()).count();

}



bool llkCheckEng(const std::string& property) {

    return android::base::GetProperty(property, "eng") == "eng";

}



bool llkInit(const char* threadname) {

    auto debuggable = android::base::GetBoolProperty("ro.debuggable", false);

    llkLowRam = android::base::GetBoolProperty("ro.config.low_ram", false);

    if (!LLK_ENABLE_DEFAULT && debuggable) {

        llkEnable = android::base::GetProperty(LLK_ENABLE_PROPERTY, "eng") == "eng";

        khtEnable = android::base::GetProperty(KHT_ENABLE_PROPERTY, "eng") == "eng";

    llkEnableSysrqT &= !llkLowRam;

    if (debuggable) {

        llkEnableSysrqT |= llkCheckEng(LLK_ENABLE_SYSRQ_T_PROPERTY);

        if (!LLK_ENABLE_DEFAULT) {  // NB: default is currently true ...

            llkEnable |= llkCheckEng(LLK_ENABLE_PROPERTY);

            khtEnable |= llkCheckEng(KHT_ENABLE_PROPERTY);

        }

    }

    llkEnableSysrqT = android::base::GetBoolProperty(LLK_ENABLE_SYSRQ_T_PROPERTY, llkEnableSysrqT);

    llkEnable = android::base::GetBoolProperty(LLK_ENABLE_PROPERTY, llkEnable);

    if (llkEnable && !llkTopDirectory.reset(procdir)) {

        // Most likely reason we could be here is llkd was started