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authorPaolo Bonzini <pbonzini@redhat.com>2018-11-14 12:36:57 +0100
committerPaolo Bonzini <pbonzini@redhat.com>2018-11-27 15:06:14 +0100
commita8efa60633575a2ee4dbf807a71cb44d44b0e0f8 (patch)
treeaa3206f7576f8a2ffd25431bdbf92ee70b65b788 /cpus.c
parentd98f26073bebddcd3da0ba1b86c3a34e840c0fb8 (diff)
cpus: run work items for all vCPUs if single-threaded
This avoids the following I/O thread deadlock: 1) the I/O thread calls run_on_cpu for CPU 3 from a timer. single_tcg_halt_cond is signaled 2) CPU 1 is running and exits. It finds no work item and enters CPU 2 3) because the I/O thread is stuck in run_on_cpu, the round-robin kick timer never triggers, and CPU 3 never runs the work item 4) run_on_cpu never completes Reviewed-by: Emilio G. Cota <cota@braap.org> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'cpus.c')
-rw-r--r--cpus.c12
1 files changed, 8 insertions, 4 deletions
diff --git a/cpus.c b/cpus.c
index a2b33ccb29..0ddeeefc14 100644
--- a/cpus.c
+++ b/cpus.c
@@ -1220,16 +1220,20 @@ static void qemu_wait_io_event_common(CPUState *cpu)
process_queued_cpu_work(cpu);
}
-static void qemu_tcg_rr_wait_io_event(CPUState *cpu)
+static void qemu_tcg_rr_wait_io_event(void)
{
+ CPUState *cpu;
+
while (all_cpu_threads_idle()) {
stop_tcg_kick_timer();
- qemu_cond_wait(cpu->halt_cond, &qemu_global_mutex);
+ qemu_cond_wait(first_cpu->halt_cond, &qemu_global_mutex);
}
start_tcg_kick_timer();
- qemu_wait_io_event_common(cpu);
+ CPU_FOREACH(cpu) {
+ qemu_wait_io_event_common(cpu);
+ }
}
static void qemu_wait_io_event(CPUState *cpu)
@@ -1562,7 +1566,7 @@ static void *qemu_tcg_rr_cpu_thread_fn(void *arg)
qemu_notify_event();
}
- qemu_tcg_rr_wait_io_event(cpu ? cpu : first_cpu);
+ qemu_tcg_rr_wait_io_event();
deal_with_unplugged_cpus();
}