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charset="utf-8" Content-Transfer-Encoding: quoted-printable Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer2=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=2a00:1450:4864:20::42f; envelope-from=alex.bennee@linaro.org; helo=mail-wr1-x42f.google.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=unavailable autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+importer2=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer2=patchew.org@nongnu.org X-ZohoMail-DKIM: pass (identity @linaro.org) X-ZM-MESSAGEID: 1674585752608100001 From: Emilio Cota To fix potential deadlocks as reported by tsan. Reviewed-by: Richard Henderson Reviewed-by: Philippe Mathieu-Daud=C3=A9 Signed-off-by: Emilio Cota Message-Id: <20230111151628.320011-6-cota@braap.org> Signed-off-by: Alex Benn=C3=A9e --- plugins/core.c | 16 +++++++++++----- 1 file 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; =20 - 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(); =20 + qemu_rec_mutex_lock(&plugin.lock); /* un-register all callbacks except the final AT_EXIT one */ for (ev =3D 0; ev < QEMU_PLUGIN_EV_MAX; ev++) { if (ev !=3D 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); =20 + tb_flush(current_cpu); end_exclusive(); =20 /* now it's safe to handle the exit case */ --=20 2.34.1