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[Qemu-devel] [PULL 02/15] cpus: run work items for all vCPUs if single-t
From: |
Paolo Bonzini |
Subject: |
[Qemu-devel] [PULL 02/15] cpus: run work items for all vCPUs if single-threaded |
Date: |
Mon, 26 Nov 2018 20:40:22 +0100 |
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 <address@hidden>
Signed-off-by: Paolo Bonzini <address@hidden>
---
cpus.c | 12 ++++++++----
1 file changed, 8 insertions(+), 4 deletions(-)
diff --git a/cpus.c b/cpus.c
index a2b33cc..0ddeeef 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();
}
--
1.8.3.1
- [Qemu-devel] [PULL 00/15] Misc patches for QEMU 3.1-rc3, Paolo Bonzini, 2018/11/26
- [Qemu-devel] [PULL 01/15] target/i386: kvm: add VMX migration blocker, Paolo Bonzini, 2018/11/26
- [Qemu-devel] [PULL 02/15] cpus: run work items for all vCPUs if single-threaded,
Paolo Bonzini <=
- [Qemu-devel] [PULL 03/15] lsi: Reselection needed to remove pending commands from queue, Paolo Bonzini, 2018/11/26
- [Qemu-devel] [PULL 04/15] migration: savevm: consult migration blockers, Paolo Bonzini, 2018/11/26
- [Qemu-devel] [PULL 06/15] vl: Improve error message when we can't load fw_cfg from file, Paolo Bonzini, 2018/11/26
- [Qemu-devel] [PULL 08/15] vl.c: remove outdated comment, Paolo Bonzini, 2018/11/26
- [Qemu-devel] [PULL 09/15] checkpatch: g_test_message does not need a trailing newline, Paolo Bonzini, 2018/11/26
- [Qemu-devel] [PULL 10/15] target/i386: Generate #UD when applying LOCK to a register destination, Paolo Bonzini, 2018/11/26
- [Qemu-devel] [PULL 07/15] vhost-user-bridge: fix recvmsg iovlen, Paolo Bonzini, 2018/11/26
- [Qemu-devel] [PULL 11/15] MAINTAINERS: Add some missing entries related to accelerators, Paolo Bonzini, 2018/11/26
- [Qemu-devel] [PULL 05/15] vmstate: constify VMStateField, Paolo Bonzini, 2018/11/26
- [Qemu-devel] [PULL 12/15] MAINTAINERS: Add an entry for the Firmware Configuration (fw_cfg) device, Paolo Bonzini, 2018/11/26