Merge tag 'pull-jan-omnibus-020223-1' of https://gitlab.com/stsquad/qemu into staging

Testing, docs, semihosting and plugin updates

  - update playbooks for custom runners
  - add section timing support to gitlab
  - upgrade fedora images to 37
  - purge perl from the build system and deps
  - disable unstable tests in CI
  - improve intro, emulation and semihosting docs
  - semihosting bug fix and O_BINARY default
  - add memory-sve test
  - fix some races in qht
  - improve plugin handling of memory helpers
  - optimise plugin hooks
  - fix some plugin deadlocks
  - reduce win64-cross build time by dropping some targets

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* tag 'pull-jan-omnibus-020223-1' of https://gitlab.com/stsquad/qemu: (36 commits)
  gitlab: cut even more from cross-win64-system build
  plugins: Iterate on cb_lists in qemu_plugin_user_exit
  cpu-exec: assert that plugin_mem_cbs is NULL after execution
  tcg: exclude non-memory effecting helpers from instrumentation
  translator: always pair plugin_gen_insn_{start, end} calls
  plugins: fix optimization in plugin_gen_disable_mem_helpers
  plugins: make qemu_plugin_user_exit's locking order consistent with fork_start's
  util/qht: use striped locks under TSAN
  thread: de-const qemu_spin_destroy
  util/qht: add missing atomic_set(hashes[i])
  cpu: free cpu->tb_jmp_cache with RCU
  tests/tcg: add memory-sve test for aarch64
  semihosting: add O_BINARY flag in host_open for NT compatibility
  semihosting: Write back semihosting data before completion callback
  docs: add an introduction to the system docs
  semihosting: add semihosting section to the docs
  docs: add a new section to outline emulation support
  docs: add hotlinks to about preface text
  MAINTAINERS: Fix the entry for tests/tcg/nios2
  gitlab: wrap up test results for custom runners
  ...

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

1 files changed, 15 insertions, 8 deletions

diff --git a/plugins/core.c b/plugins/core.c
index ccb770a485..e04ffa1ba4 100644
--- a/plugins/core.c
+++ b/plugins/core.c
@@ -500,26 +500,33 @@ void qemu_plugin_user_exit(void)
     enum qemu_plugin_event ev;
     CPUState *cpu;
 
-    QEMU_LOCK_GUARD(&plugin.lock);
-
+    /*
+     * Locking order: we must acquire locks in an order that is consistent
+     * with the one in fork_start(). That is:
+     * - start_exclusive(), which acquires qemu_cpu_list_lock,
+     *   must be called before acquiring plugin.lock.
+     * - tb_flush(), which acquires mmap_lock(), must be called
+     *   while plugin.lock is not held.
+     */
     start_exclusive();
 
+    qemu_rec_mutex_lock(&plugin.lock);
     /* un-register all callbacks except the final AT_EXIT one */
     for (ev = 0; ev < QEMU_PLUGIN_EV_MAX; ev++) {
         if (ev != QEMU_PLUGIN_EV_ATEXIT) {
-            struct qemu_plugin_ctx *ctx;
-            QTAILQ_FOREACH(ctx, &plugin.ctxs, entry) {
-                plugin_unregister_cb__locked(ctx, ev);
+            struct qemu_plugin_cb *cb, *next;
+
+            QLIST_FOREACH_SAFE_RCU(cb, &plugin.cb_lists[ev], entry, next) {
+                plugin_unregister_cb__locked(cb->ctx, ev);
             }
         }
     }
-
-    tb_flush(current_cpu);
-
     CPU_FOREACH(cpu) {
         qemu_plugin_disable_mem_helpers(cpu);
     }
+    qemu_rec_mutex_unlock(&plugin.lock);
 
+    tb_flush(current_cpu);
     end_exclusive();
 
     /* now it's safe to handle the exit case */