gdb-remote: Make the sequence mutex non-recursive

Summary:
This is a preparatory commit for D22914, where I'd like to replace this mutex by an R/W lock
(which is also not recursive). This required a couple of changes:
- The only caller of Read/WriteRegister, GDBRemoteRegisterContext class, was already acquiring
  the mutex, so these functions do not need to. All functions which now do not take a lock, take
  an lock argument instead, to remind the caller of this fact.
- GetThreadSuffixSupported() was being called from locked and unlocked contexts (including
  contexts where the process was running, and the call would fail if it did not have the result
  cached). I have split this into two functions, one which computes the thread suffix support and
  caches it (this one always takes the lock), and another, which returns the cached value (and
  never needs to take the lock). This feels quite natural as ProcessGdbRemote was already
  pre-caching this value at the start.

Reviewers: clayborg

Subscribers: lldb-commits

Differential Revision: https://reviews.llvm.org/D23802

llvm-svn: 279725

1 files changed, 12 insertions, 8 deletions

diff --git a/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationClient.h b/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationClient.h
index eeeecb53992..a714b403bab 100644
--- a/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationClient.h
+++ b/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationClient.h
@@ -64,6 +64,9 @@ public:
     SendPacketsAndConcatenateResponses (const char *send_payload_prefix,
                                         std::string &response_string);
 
+    void
+    ComputeThreadSuffixSupport();
+
     bool
     GetThreadSuffixSupported();
 
@@ -395,9 +398,6 @@ public:
                          uint32_t recv_size);
     
     bool
-    SetCurrentThread (uint64_t tid);
-    
-    bool
     SetCurrentThreadForRun (uint64_t tid);
 
     bool
@@ -488,17 +488,18 @@ public:
 
     lldb::DataBufferSP
     ReadRegister(lldb::tid_t tid,
-                 uint32_t reg_num); // Must be the eRegisterKindProcessPlugin register number
+                 uint32_t reg_num, // Must be the eRegisterKindProcessPlugin register number
+                 const Lock &lock);
 
     lldb::DataBufferSP
-    ReadAllRegisters(lldb::tid_t tid);
+    ReadAllRegisters(lldb::tid_t tid, const Lock &lock);
 
     bool
     WriteRegister(lldb::tid_t tid, uint32_t reg_num, // eRegisterKindProcessPlugin register number
-                  llvm::ArrayRef<uint8_t> data);
+                  llvm::ArrayRef<uint8_t> data, const Lock &lock);
 
     bool
-    WriteAllRegisters(lldb::tid_t tid, llvm::ArrayRef<uint8_t> data);
+    WriteAllRegisters(lldb::tid_t tid, llvm::ArrayRef<uint8_t> data, const Lock &lock);
 
     bool
     SaveRegisterState(lldb::tid_t tid, uint32_t &save_id);
@@ -686,7 +687,10 @@ protected:
 
     PacketResult
     SendThreadSpecificPacketAndWaitForResponse(lldb::tid_t tid, StreamString &&payload,
-                                               StringExtractorGDBRemote &response, bool send_async);
+                                               StringExtractorGDBRemote &response, const Lock &lock);
+
+    bool
+    SetCurrentThread(uint64_t tid, const Lock &lock);
 
 private:
     DISALLOW_COPY_AND_ASSIGN (GDBRemoteCommunicationClient);