On 24/09/2018 20:46, Emilio G. Cota wrote:
> Applying this on my local tree is deadlocking icount, since
> cpu_update_icount is called from cpu_get_icount_raw_locked:
>
> #6 cpu_update_icount (cpu=<optimized out>) at /data/src/qemu/cpus.c:257
> #7 0x000055a6fbc7ae5c in cpu_get_icount_raw_locked () at
> /data/src/qemu/cpus.c:271
> #8 0x000055a6fbc7ae99 in cpu_get_icount_locked () at
> /data/src/qemu/cpus.c:279
> #9 0x000055a6fbc7b3ac in cpu_get_icount () at /data/src/qemu/cpus.c:302
> #10 0x000055a6fc0f3a05 in qemu_clock_get_ns
> (type=type@entry=QEMU_CLOCK_VIRTUAL) at /data/src/qemu/util/qemu-timer.c:601
>
> I am however not sure what Paolo's queued tree looks like, so I
> might be missing something.
No, you're not missing anything.
Looking at other callers of cpu_update_icount, this should be the fix:
diff --git a/cpus.c b/cpus.c
index b429b5a9e0..551076fb98 100644
--- a/cpus.c
+++ b/cpus.c
@@ -245,15 +245,25 @@ static int64_t cpu_get_icount_executed(CPUState *cpu)
* account executed instructions. This is done by the TCG vCPU
* thread so the main-loop can see time has moved forward.
*/
-void cpu_update_icount(CPUState *cpu)
+static void cpu_update_icount_locked(CPUState *cpu)
{
int64_t executed = cpu_get_icount_executed(cpu);
cpu->icount_budget -= executed;
- seqlock_write_lock(&timers_state.vm_clock_seqlock,
- &timers_state.vm_clock_lock);
atomic_set_i64(&timers_state.qemu_icount,
timers_state.qemu_icount + executed);
+}
+
+/*
+ * Update the global shared timer_state.qemu_icount to take into
+ * account executed instructions. This is done by the TCG vCPU
+ * thread so the main-loop can see time has moved forward.
+ */
+void cpu_update_icount(CPUState *cpu)
+{
+ seqlock_write_lock(&timers_state.vm_clock_seqlock,
+ &timers_state.vm_clock_lock);
+ cpu_update_icount_locked(cpu);
seqlock_write_unlock(&timers_state.vm_clock_seqlock,
&timers_state.vm_clock_lock);
}
@@ -268,7 +278,7 @@ static int64_t cpu_get_icount_raw_locked(void)
exit(1);
}
/* Take into account what has run */
- cpu_update_icount(cpu);
+ cpu_update_icount_locked(cpu);
}
/* The read is protected by the seqlock, but needs atomic64 to avoid UB */
return atomic_read_i64(&timers_state.qemu_icount);
> Paolo: is that tree available anywhere?
Nope, unfortunately some patches I've queued broke on 32-bit and stuff so I
couldn't send out the pull request before leaving for Kernel Recipes...
Paolo
