Hi Sean,
On 7/19/22 9:46 AM, Sean Christopherson wrote:
On Tue, Jul 19, 2022, Gavin Shan wrote:
v3: Improved changelog (Oliver Upon)
Sorry I didn't catch v3, I saw that you waited but just didn't get to this earlier :-/
Not a problem at all :)
tools/testing/selftests/kvm/rseq_test.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/tools/testing/selftests/kvm/rseq_test.c b/tools/testing/selftests/kvm/rseq_test.c index 4158da0da2bb..c83ac7b467f8 100644 --- a/tools/testing/selftests/kvm/rseq_test.c +++ b/tools/testing/selftests/kvm/rseq_test.c @@ -38,6 +38,7 @@ static __thread volatile struct rseq __rseq = { */ #define NR_TASK_MIGRATIONS 100000 +static pid_t rseq_tid; static pthread_t migration_thread; static cpu_set_t possible_mask; static int min_cpu, max_cpu; @@ -106,7 +107,8 @@ static void *migration_worker(void *ign)
Pass the target TID to the worker, then there's no need to use a global and no chance of consuming rseq_tid "uninitialized". The casting to convert gettid() to a "void *" is annoying, but not the end of the world.
I was thinking of the scheme, but passing the address of a local variable for the thread ID. Your suggestion also makes sense to me.
* stable, i.e. while changing affinity is in-progress. */ smp_wmb();
r = sched_setaffinity(0, sizeof(allowed_mask), &allowed_mask);
r = sched_setaffinity(rseq_tid, sizeof(allowed_mask),&allowed_mask);Eh, let this poke out, don't think it's worth wrapping here.
Ok, I was trying to follow rule of 80-characters per line, even it's not strictly needed nowadays. It's also fine not to follow :)
I just picked your code and posted v4:
https://lore.kernel.org/kvmarm/20220719020830.3479482-1-gshan@redhat.com/T/#...
Thanks, Gavin
E.g.
tools/testing/selftests/kvm/rseq_test.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-)
diff --git a/tools/testing/selftests/kvm/rseq_test.c b/tools/testing/selftests/kvm/rseq_test.c index aba7be178dab..a54d4d05a058 100644 --- a/tools/testing/selftests/kvm/rseq_test.c +++ b/tools/testing/selftests/kvm/rseq_test.c @@ -80,8 +80,9 @@ static int next_cpu(int cpu) return cpu; }
-static void *migration_worker(void *ign) +static void *migration_worker(void *__rseq_tid) {
- pid_t rseq_tid = (pid_t)(unsigned long)__rseq_tid; cpu_set_t allowed_mask; int r, i, cpu;
@@ -104,7 +105,7 @@ static void *migration_worker(void *ign) * stable, i.e. while changing affinity is in-progress. */ smp_wmb();
r = sched_setaffinity(0, sizeof(allowed_mask), &allowed_mask);
r = sched_setaffinity(rseq_tid, sizeof(allowed_mask), &allowed_mask);@@ -227,7 +228,8 @@ int main(int argc, char *argv[]) vm = vm_create_with_one_vcpu(&vcpu, guest_code); ucall_init(vm, NULL);
- pthread_create(&migration_thread, NULL, migration_worker, 0);
pthread_create(&migration_thread, NULL, migration_worker,
(void *)(unsigned long)gettid());for (i = 0; !done; i++) { vcpu_run(vcpu);
base-commit: ad6cb756bb497997032df2bda7cbdff076e4a66a