* Kir Kolyshkin <kolyshkin@xxxxxxxxx> wrote:
> Both glibc and musl define struct sched_param in sched.h, while kernel
> has it in uapi/linux/sched/types.h, making it cumbersome to use
> sched_getattr(2) or sched_setattr(2) from userspace.
>
> For example, something like this:
>
> #include <sched.h>
> #include <linux/sched/types.h>
>
> struct sched_attr sa;
>
> will result in "error: redefinition of ‘struct sched_param’" (note the
> code doesn't need sched_param at all -- it needs struct sched_attr
> plus some stuff from sched.h).
>
> The situation is, glibc is not going to provide a wrapper for
> sched_{get,set}attr, thus the need to include linux/sched_types.h
> directly, which leads to the above problem.
Meh, I truly detest this patch, because 'struct sched_param' is very much
part of the syscall ABI signature:
include/linux/syscalls.h:
asmlinkage long sys_sched_setparam(pid_t pid,
struct sched_param __user *param);
asmlinkage long sys_sched_setscheduler(pid_t pid, int policy,
struct sched_param __user *param);
asmlinkage long sys_sched_getparam(pid_t pid,
struct sched_param __user *param);
... but OTOH let's not pretend that UAPI headers have much justification
to exist unless they are useful & can be utilized in some of the most
common user-space library environments as-is. Namespace collisions happen.
So I'm inclined to apply this workaround, but changed the title and added
the caveat below to the changelog:
sched/headers: Move 'struct sched_param' out of uapi, to work around glibc/musl breakage
...
Oh, and here is the previous attempt to fix the issue:
https://lore.kernel.org/all/20200528135552.GA87103@xxxxxxxxxx/
While I support Linus arguments, the issue is still here
and needs to be fixed.
[ mingo: Linus is right, this shouldn't be needed - but on the other
hand I agree that this header is not really helpful to
user-space as-is. So let's pretend that
<uapi/linux/sched/types.h> is only about sched_attr, and
call this commit a workaround for user-space breakage
that it in reality is ... Also, remove the Fixes tag. ]
So unless Linus objects, I'll apply this to tip:sched/core for a v6.7 merge.
Thanks,
Ingo
