Merge tag 'pull-maintainer-9.1-rc3-160824-1' of https://gitlab.com/stsquad/qemu into staging

Some fixes for 9.1-rc3 (build, replay, docs, plugins)

  - re-enable gdbsim-r5f562n8 test
  - ensure updates to python deps re-trigger configure
  - tweak configure detection of GDB MTE support
  - make checkpatch emit more warnings on updating headers
  - allow i386 access_ptr to force slow path for plugins
  - fixe some replay regressions
  - update the replay-dump tool
  - better handle muxed chardev during replay
  - clean up TCG plugins docs to mention scoreboards
  - fix plugin scoreboard race condition

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* tag 'pull-maintainer-9.1-rc3-160824-1' of https://gitlab.com/stsquad/qemu: (21 commits)
  plugins: fix race condition with scoreboards
  docs/devel: update tcg-plugins page
  docs: Fix some typos (found by typos) and grammar issues
  savevm: Fix load_snapshot error path crash
  virtio-net: Use virtual time for RSC timers
  virtio-net: Use replay_schedule_bh_event for bhs that affect machine state
  chardev: set record/replay on the base device of a muxed device
  tests/avocado: replay_kernel.py add x86-64 q35 machine test
  Revert "replay: stop us hanging in rr_wait_io_event"
  replay: allow runstate shutdown->running when replaying trace
  tests/avocado: excercise scripts/replay-dump.py in replay tests
  scripts/replay-dump.py: rejig decoders in event number order
  scripts/replay-dump.py: Update to current rr record format
  buildsys: Fix building without plugins on Darwin
  target/i386: allow access_ptr to force slow path on failed probe
  scripts/checkpatch: more checks on files imported from Linux
  configure: Fix GDB version detection for GDB_HAS_MTE
  configure: Avoid use of param. expansion when using gdb_version
  configure: Fix arch detection for GDB_HAS_MTE
  Makefile: trigger re-configure on updated pythondeps
  ...

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

1 files changed, 31 insertions, 12 deletions

diff --git a/plugins/core.c b/plugins/core.c
index 12c67b4b4e..2897453cac 100644
--- a/plugins/core.c
+++ b/plugins/core.c
@@ -214,30 +214,49 @@ CPUPluginState *qemu_plugin_create_vcpu_state(void)
 
 static void plugin_grow_scoreboards__locked(CPUState *cpu)
 {
-    if (cpu->cpu_index < plugin.scoreboard_alloc_size) {
+    size_t scoreboard_size = plugin.scoreboard_alloc_size;
+    bool need_realloc = false;
+
+    if (cpu->cpu_index < scoreboard_size) {
         return;
     }
 
-    bool need_realloc = FALSE;
-    while (cpu->cpu_index >= plugin.scoreboard_alloc_size) {
-        plugin.scoreboard_alloc_size *= 2;
-        need_realloc = TRUE;
+    while (cpu->cpu_index >= scoreboard_size) {
+        scoreboard_size *= 2;
+        need_realloc = true;
     }
 
+    if (!need_realloc) {
+        return;
+    }
 
-    if (!need_realloc || QLIST_EMPTY(&plugin.scoreboards)) {
-        /* nothing to do, we just updated sizes for future scoreboards */
+    if (QLIST_EMPTY(&plugin.scoreboards)) {
+        /* just update size for future scoreboards */
+        plugin.scoreboard_alloc_size = scoreboard_size;
         return;
     }
 
+    /*
+     * A scoreboard creation/deletion might be in progress. If a new vcpu is
+     * initialized at the same time, we are safe, as the new
+     * plugin.scoreboard_alloc_size was not yet written.
+     */
+    qemu_rec_mutex_unlock(&plugin.lock);
+
     /* cpus must be stopped, as tb might still use an existing scoreboard. */
     start_exclusive();
-    struct qemu_plugin_scoreboard *score;
-    QLIST_FOREACH(score, &plugin.scoreboards, entry) {
-        g_array_set_size(score->data, plugin.scoreboard_alloc_size);
+    /* re-acquire lock */
+    qemu_rec_mutex_lock(&plugin.lock);
+    /* in case another vcpu is created between unlock and exclusive section. */
+    if (scoreboard_size > plugin.scoreboard_alloc_size) {
+        struct qemu_plugin_scoreboard *score;
+        QLIST_FOREACH(score, &plugin.scoreboards, entry) {
+            g_array_set_size(score->data, scoreboard_size);
+        }
+        plugin.scoreboard_alloc_size = scoreboard_size;
+        /* force all tb to be flushed, as scoreboard pointers were changed. */
+        tb_flush(cpu);
     }
-    /* force all tb to be flushed, as scoreboard pointers were changed. */
-    tb_flush(cpu);
     end_exclusive();
 }