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