diff options
| author | Emilio Cota <cota@braap.org> | 2023-01-24 18:01:22 +0000 |
|---|---|---|
| committer | Alex Bennée <alex.bennee@linaro.org> | 2023-02-02 11:48:20 +0000 |
| commit | 2bbbc1be8d9a21b25d0c80b9a7345074d54abd51 (patch) | |
| tree | 333315f85cf2c360c3611e9cb3fd8b56a23c39dd /plugins | |
| parent | 68f7b2be532ad5b134cd0053173641cf52cfa247 (diff) | |
plugins: make qemu_plugin_user_exit's locking order consistent with fork_start's
To fix potential deadlocks as reported by tsan.
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Emilio Cota <cota@braap.org>
Message-Id: <20230111151628.320011-6-cota@braap.org>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20230124180127.1881110-31-alex.bennee@linaro.org>
Diffstat (limited to 'plugins')
| -rw-r--r-- | plugins/core.c | 16 |
1 files changed, 11 insertions, 5 deletions
diff --git a/plugins/core.c b/plugins/core.c index ccb770a485..728bacef95 100644 --- a/plugins/core.c +++ b/plugins/core.c @@ -500,10 +500,17 @@ 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) { @@ -513,13 +520,12 @@ void qemu_plugin_user_exit(void) } } } - - 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 */ |