Accelerators & CPU patches for Halloween 2025

[PULL 1/9] cpus: Access CPUState::thread_kicked atomically

Philippe Mathieu-Daudé posted 9 patches 1 week, 6 days ago

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Maintainers: Richard Henderson <richard.henderson@linaro.org>, Paolo Bonzini <pbonzini@redhat.com>, "Philippe Mathieu-Daudé" <philmd@linaro.org>, Eduardo Habkost <eduardo@habkost.net>, Marcel Apfelbaum <marcel.apfelbaum@gmail.com>, Yanan Wang <wangyanan55@huawei.com>, Zhao Liu <zhao1.liu@intel.com>, Alexander Graf <agraf@csgraf.de>, Mads Ynddal <mads@ynddal.dk>, Peter Maydell <peter.maydell@linaro.org>, Cameron Esfahani <dirty@apple.com>, Roman Bolshakov <rbolshakov@ddn.com>, Phil Dennis-Jordan <phil@philjordan.eu>, Yoshinori Sato <yoshinori.sato@nifty.com>

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[PULL 1/9] cpus: Access CPUState::thread_kicked atomically

Posted by Philippe Mathieu-Daudé 1 week, 6 days ago

cpus_kick_thread() is called via cpu_exit() -> qemu_cpu_kick(),
and also via gdb_syscall_handling(). Access the CPUState field
using atomic accesses. See commit 8ac2ca02744 ("accel: use atomic
accesses for exit_request") for rationale.

Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Manos Pitsidianakis <manos.pitsidianakis@linaro.org>
Message-Id: <20250925025520.71805-3-philmd@linaro.org>
---
 system/cpus.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/system/cpus.c b/system/cpus.c
index aa7bfcf56e5..74f5a5bd4e2 100644
--- a/system/cpus.c
+++ b/system/cpus.c
@@ -480,10 +480,10 @@ void qemu_process_cpu_events(CPUState *cpu)
 
 void cpus_kick_thread(CPUState *cpu)
 {
-    if (cpu->thread_kicked) {
+    if (qatomic_read(&cpu->thread_kicked)) {
         return;
     }
-    cpu->thread_kicked = true;
+    qatomic_set(&cpu->thread_kicked, true);
 
 #ifndef _WIN32
     int err = pthread_kill(cpu->thread->thread, SIG_IPI);
-- 
2.51.0