Re: git: f3f350c5c8e4 - stable/13 - cpuset: Add compat shim to the sched_affinity functions

On Sun, Feb 19, 2023 at 07:26:18AM +0000, Dmitry Chagin wrote:
> The branch stable/13 has been updated by dchagin:
> 
> URL: https://cgit.FreeBSD.org/src/commit/?id=f3f350c5c8e4f6b0d3ff9806881b8f042a9ca925
> 
> commit f3f350c5c8e4f6b0d3ff9806881b8f042a9ca925
> Author:     Dmitry Chagin <dchagin@FreeBSD.org>
> AuthorDate: 2023-02-15 09:23:15 +0000
> Commit:     Dmitry Chagin <dchagin@FreeBSD.org>
> CommitDate: 2023-02-19 07:26:06 +0000
> 
>     cpuset: Add compat shim to the sched_affinity functions
>     
>     To allow to run a newer world on a pre-1400079 kernel a compat shims to
>     the sched_affinity functions has beed added.
>     
>     Reported by:            antoine
>     Tested by:              antoine
>     Reviewed by:            kib
>     Differential revision:  https://reviews.freebsd.org/D38555
>     MFC after:              3 days
>     
>     (cherry picked from commit cbc32e4c5e8427e0f1032d9d3aa5863dd1538c11)
> ---
>  lib/libc/gen/sched_getaffinity.c | 15 ++++++++++++++-
>  lib/libc/gen/sched_setaffinity.c | 14 +++++++++++++-
>  lib/libc/include/libc_private.h  |  6 ++++++
>  sys/sys/param.h                  |  1 +
>  4 files changed, 34 insertions(+), 2 deletions(-)
> 
> diff --git a/lib/libc/gen/sched_getaffinity.c b/lib/libc/gen/sched_getaffinity.c
> index 95145a1eb019..fce47fbfc0d2 100644
> --- a/lib/libc/gen/sched_getaffinity.c
> +++ b/lib/libc/gen/sched_getaffinity.c
> @@ -26,16 +26,29 @@
>   * SUCH DAMAGE.
>   */
>  
> +#define	_WANT_P_OSREL
> +#include <sys/param.h>
>  #include <errno.h>
>  #include <sched.h>
>  #include <string.h>
>  
> +#include "libc_private.h"
> +
>  int
>  sched_getaffinity(pid_t pid, size_t cpusetsz, cpuset_t *cpuset)
>  {
> +	cpuwhich_t which;
>  	int error;
>  
> -	error = cpuset_getaffinity(CPU_LEVEL_WHICH, CPU_WHICH_TIDPID,
> +	if (__getosreldate() < P_OSREL_TIDPID) {
> +		if (pid == 0 || pid > _PID_MAX)
> +			which = CPU_WHICH_TID;
> +		else
> +			which = CPU_WHICH_PID;
> +	} else
> +		which = CPU_WHICH_TIDPID;
> +
> +	error = cpuset_getaffinity(CPU_LEVEL_WHICH, which,
>  	    pid == 0 ? -1 : pid, cpusetsz, cpuset);
>  	if (error == -1 && errno == ERANGE)
>  		errno = EINVAL;
> diff --git a/lib/libc/gen/sched_setaffinity.c b/lib/libc/gen/sched_setaffinity.c
> index 36ed0f45d417..b878e1affc41 100644
> --- a/lib/libc/gen/sched_setaffinity.c
> +++ b/lib/libc/gen/sched_setaffinity.c
> @@ -26,20 +26,32 @@
>   * SUCH DAMAGE.
>   */
>  
> +#define	_WANT_P_OSREL
>  #include <sys/param.h>
>  #include <sys/sysctl.h>
>  #include <errno.h>
>  #include <sched.h>
>  #include <string.h>
>  
> +#include "libc_private.h"
> +
>  int
>  sched_setaffinity(pid_t pid, size_t cpusetsz, const cpuset_t *cpuset)
>  {
>  	static int mp_maxid;
> +	cpuwhich_t which;
>  	cpuset_t c;
>  	int error, lbs, cpu;
>  	size_t len, sz;
>  
> +	if (__getosreldate() < P_OSREL_TIDPID) {
> +		if (pid == 0 || pid > _PID_MAX)
> +			which = CPU_WHICH_TID;
> +		else
> +			which = CPU_WHICH_PID;
> +	} else
> +		which = CPU_WHICH_TIDPID;
> +
>  	sz = cpusetsz > sizeof(cpuset_t) ? sizeof(cpuset_t) : cpusetsz;
>  	memset(&c, 0, sizeof(c));
>  	memcpy(&c, cpuset, sz);
> @@ -58,7 +70,7 @@ sched_setaffinity(pid_t pid, size_t cpusetsz, const cpuset_t *cpuset)
>  			if (cpu > mp_maxid)
>  				CPU_CLR(cpu, &c);
>  	}
> -	error = cpuset_setaffinity(CPU_LEVEL_WHICH, CPU_WHICH_TIDPID,
> +	error = cpuset_setaffinity(CPU_LEVEL_WHICH, which,
>  	    pid == 0 ? -1 : pid, sizeof(cpuset_t), &c);
>  	if (error == -1 && errno == EDEADLK)
>  		errno = EINVAL;
> diff --git a/lib/libc/include/libc_private.h b/lib/libc/include/libc_private.h
> index 61c1eb438142..78a75cc6284d 100644
> --- a/lib/libc/include/libc_private.h
> +++ b/lib/libc/include/libc_private.h
> @@ -39,6 +39,12 @@
>  #include <sys/_types.h>
>  #include <sys/_pthreadtypes.h>
>  
> +/*
> + * The kernel doesn't expose PID_MAX to the user space. Save it here
> + * to allow to run a newer world on a pre-1400079 kernel.
> + */
> +#define	_PID_MAX	99999
> +
>  /*
>   * This global flag is non-zero when a process has created one
>   * or more threads. It is used to avoid calling locking functions
> diff --git a/sys/sys/param.h b/sys/sys/param.h
> index 909ff0ef1d8b..d2fbad6c127b 100644
> --- a/sys/sys/param.h
> +++ b/sys/sys/param.h
> @@ -91,6 +91,7 @@
>  #define	P_OSREL_CK_SUPERBLOCK		1300000
>  #define	P_OSREL_CK_INODE		1300005
>  #define	P_OSREL_POWERPC_NEW_AUX_ARGS	1300070
> +#define	P_OSREL_TIDPID			1400079
Does it work to have 14.x osrel value for P_OSREL_TIDPID as compat selector
on 13.x?

>  
>  #define	P_OSREL_MAJOR(x)		((x) / 100000)
>  #endif