Merge "llkd: llkSplit should prevent empty entries"

llkd/README.md

@@ -60,7 +60,7 @@ kernel instead of deal with more graceful kill operation.
 Android Properties
 ------------------
 
-Android Properties llkd respond to (<prop>_ms parms are in milliseconds):
+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).
@@ -99,19 +99,33 @@ default 2 minutes samples of threads for D or Z.
 #### ro.llk.blacklist.process
 default 0,1,2 (kernel, init and [kthreadd]) plus process names
 init,[kthreadd],[khungtaskd],lmkd,lmkd.llkd,llkd,watchdogd,
-[watchdogd],[watchdogd/0],...,[watchdogd/<get_nprocs-1>].
+[watchdogd],[watchdogd/0],...,[watchdogd/***get_nprocs**-1*].
+The string false is the equivalent to an empty list.
+Do not watch these processes.  A process can be comm, cmdline or pid reference.
+NB: automated default here can be larger than the current maximum property
+size of 92.
+NB: false is a very very very unlikely process to want to blacklist.
 
 #### ro.llk.blacklist.parent
 default 0,2 (kernel and [kthreadd]).
+The string false is the equivalent to an empty list.
+Do not watch processes that have this parent.
+A parent process can be comm, cmdline or pid reference.
 
 #### ro.llk.blacklist.uid
-default <empty>, comma separated list of uid numbers or names.
+default *empty* or false, comma separated list of uid numbers or names.
+The string false is the equivalent to an empty list.
+Do not watch processes that match this uid.
 
 Architectural Concerns
 ----------------------
 
+- built-in [khungtask] daemon is too generic and trips on driver code that
+  sits around in D state too much.  To switch to S instead makes the task(s)
+  killable, so the drivers should be able to resurrect them if needed.
+- Properties are limited to 92 characters.
 - Create kernel module and associated gTest to actually test panic.
-- Create gTest to test out blacklist (ro.llk.blacklist.<properties> generally
+- Create gTest to test out blacklist (ro.llk.blacklist.*properties* generally
   not be inputs).  Could require more test-only interfaces to libllkd.
-- Speed up gTest using something else than ro.llk.<properties>, which should
-  not be inputs.
+- Speed up gTest using something else than ro.llk.*properties*, which should
+  not be inputs as they should be baked into the product.

llkd/libllkd.cpp

@@ -285,7 +285,7 @@ struct proc {
           schedUpdate(0),
           nrSwitches(0),
           update(llkUpdate),
-          count(0),
+          count(0ms),
           pid(pid),
           ppid(ppid),
           uid(-1),
@@ -574,15 +574,19 @@ std::string llkFormat(const std::unordered_set<std::string>& blacklist) {
 
 // We only officially support comma separators, but wetware being what they
 // are will take some liberty and I do not believe they should be punished.
-std::unordered_set<std::string> llkSplit(const std::string& s,
-                                         const std::string& delimiters = ", \t:") {
+std::unordered_set<std::string> llkSplit(const std::string& s) {
     std::unordered_set<std::string> result;
 
+    // Special case, allow boolean false to empty the list, otherwise expected
+    // source of input from android::base::GetProperty will supply the default
+    // value on empty content in the property.
+    if (s == "false") return result;
+
     size_t base = 0;
-    size_t found;
-    while (true) {
-        found = s.find_first_of(delimiters, base);
-        result.emplace(s.substr(base, found - base));
+    while (s.size() > base) {
+        auto found = s.find_first_of(", \t:", base);
+        // Only emplace content, empty entries are not an option
+        if (found != base) result.emplace(s.substr(base, found - base));
         if (found == s.npos) break;
         base = found + 1;
     }