Re: [PATCH 2/5] glibc: sched_getcpu(): use rseq cpu_id TLS on Linux (v2)

Szabolcs Nagy
2019-04-18T15:34:06Z

On 16/04/2019 18:32, Mathieu Desnoyers wrote:
> --- a/sysdeps/unix/sysv/linux/sched_getcpu.c
> +++ b/sysdeps/unix/sysv/linux/sched_getcpu.c
> @@ -37,3 +37,26 @@ sched_getcpu (void)
> return -1;
> #endif
> }
> +
> +#ifdef __NR_rseq
> +#include <sys/rseq.h>
> +#endif
> +
> +#if defined __NR_rseq && defined RSEQ_SIG
> +extern __attribute__ ((tls_model ("initial-exec")))
> +__thread volatile struct rseq __rseq_abi;

i'd expect sys/rseq.h to provide this declaration.

> +
> +int
> +sched_getcpu (void)
> +{
> + int cpu_id = __rseq_abi.cpu_id;
> +
> + return cpu_id >= 0 ? cpu_id : vsyscall_sched_getcpu ();
> +}
> +#else
> +int
> +sched_getcpu (void)
> +{
> + return vsyscall_sched_getcpu ();
> +}
> +#endif
> -- 2.17.1
>