| Message ID | 20200520140541.30256-13-alex.bennee@linaro.org |
|---|---|
| State | Superseded |
| Headers | show |
| Series | testing and plugin updates | expand |
On 5/20/20 7:05 AM, Alex Bennée wrote: > Basing the cpu_index on the number of currently allocated vCPUs fails > when vCPUs aren't removed in a LIFO manner. This is especially true > when we are allocating a cpu_index for each guest thread in > linux-user where there is no ordering constraint on their allocation > and de-allocation. > > [I've dropped the assert which is there to guard against out-of-order > removal as this should probably be caught higher up the stack. Maybe > we could just ifdef CONFIG_SOFTTMU it?] > > Signed-off-by: Alex Bennée <alex.bennee@linaro.org> > Cc: Nikolay Igotti <igotti@gmail.com> > Cc: Paolo Bonzini <pbonzini@redhat.com> > Cc: Igor Mammedov <imammedo@redhat.com> > Cc: Eduardo Habkost <ehabkost@redhat.com> > > --- > v2 > - slightly tweak the index algorithm to preserve cpu_index = 0 > --- > cpus-common.c | 10 +++++----- > 1 file changed, 5 insertions(+), 5 deletions(-) Reviewed-by: Richard Henderson <richard.henderson@linaro.org> r~
diff --git a/cpus-common.c b/cpus-common.c index 55d5df89237..70a9d12981a 100644 --- a/cpus-common.c +++ b/cpus-common.c @@ -61,13 +61,15 @@ static bool cpu_index_auto_assigned; static int cpu_get_free_index(void) { CPUState *some_cpu; - int cpu_index = 0; + int max_cpu_index = 0; cpu_index_auto_assigned = true; CPU_FOREACH(some_cpu) { - cpu_index++; + if (some_cpu->cpu_index >= max_cpu_index) { + max_cpu_index = some_cpu->cpu_index + 1; + } } - return cpu_index; + return max_cpu_index; } void cpu_list_add(CPUState *cpu) @@ -90,8 +92,6 @@ void cpu_list_remove(CPUState *cpu) return; } - assert(!(cpu_index_auto_assigned && cpu != QTAILQ_LAST(&cpus))); - QTAILQ_REMOVE_RCU(&cpus, cpu, node); cpu->cpu_index = UNASSIGNED_CPU_INDEX; }
Basing the cpu_index on the number of currently allocated vCPUs fails when vCPUs aren't removed in a LIFO manner. This is especially true when we are allocating a cpu_index for each guest thread in linux-user where there is no ordering constraint on their allocation and de-allocation. [I've dropped the assert which is there to guard against out-of-order removal as this should probably be caught higher up the stack. Maybe we could just ifdef CONFIG_SOFTTMU it?] Signed-off-by: Alex Bennée <alex.bennee@linaro.org> Cc: Nikolay Igotti <igotti@gmail.com> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Igor Mammedov <imammedo@redhat.com> Cc: Eduardo Habkost <ehabkost@redhat.com> --- v2 - slightly tweak the index algorithm to preserve cpu_index = 0 --- cpus-common.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) -- 2.20.1