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sched: Have sched_class_highest define by vmlinux.lds.h

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Now that the sched_class descriptors are defined by the linker script, and
this needs to be aware of the existance of stop_sched_class when SMP is
enabled or not, as it is used as the "highest" priority when defined. Move
the declaration of sched_class_highest to the same location in the linker
script that inserts stop_sched_class, and this will also make it easier to
see what should be defined as the highest class, as this linker script
location defines the priorities as well.

Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20191219214558.682913590@goodmis.org
This commit is contained in:
Steven Rostedt (VMware) 2019-12-19 16:44:53 -05:00 committed by Peter Zijlstra
parent 590d697963
commit c3a340f7e7
3 changed files with 21 additions and 9 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

5
include/asm-generic/vmlinux.lds.h
View file

@ -114,11 +114,14 @@
* relation to each other.
*/
#define SCHED_DATA \
STRUCT_ALIGN(); \
__begin_sched_classes = .; \
*(__idle_sched_class) \
*(__fair_sched_class) \
*(__rt_sched_class) \
*(__dl_sched_class) \
*(__stop_sched_class)
*(__stop_sched_class) \
__end_sched_classes = .;
/*
* Align to a 32 byte boundary equal to the

8
kernel/sched/core.c
View file

@ -6646,6 +6646,14 @@ void __init sched_init(void)
unsigned long ptr = 0;
int i;
/* Make sure the linker didn't screw up */
BUG_ON(&idle_sched_class + 1 != &fair_sched_class ||
&fair_sched_class + 1 != &rt_sched_class ||
&rt_sched_class + 1 != &dl_sched_class);
#ifdef CONFIG_SMP
BUG_ON(&dl_sched_class + 1 != &stop_sched_class);
#endif
wait_bit_init();
#ifdef CONFIG_FAIR_GROUP_SCHED

17
kernel/sched/sched.h
View file

@ -1811,7 +1811,7 @@ struct sched_class {
#ifdef CONFIG_FAIR_GROUP_SCHED
void (*task_change_group)(struct task_struct *p, int type);
#endif
};
} __aligned(32); /* STRUCT_ALIGN(), vmlinux.lds.h */
static inline void put_prev_task(struct rq *rq, struct task_struct *prev)
{
@ -1825,17 +1825,18 @@ static inline void set_next_task(struct rq *rq, struct task_struct *next)
next->sched_class->set_next_task(rq, next, false);
}
#ifdef CONFIG_SMP
#define sched_class_highest (&stop_sched_class)
#else
#define sched_class_highest (&dl_sched_class)
#endif
/* Defined in include/asm-generic/vmlinux.lds.h */
extern struct sched_class __begin_sched_classes[];
extern struct sched_class __end_sched_classes[];
#define sched_class_highest (__end_sched_classes - 1)
#define sched_class_lowest (__begin_sched_classes - 1)
#define for_class_range(class, _from, _to) \
for (class = (_from); class != (_to); class = class->next)
for (class = (_from); class != (_to); class--)
#define for_each_class(class) \
for_class_range(class, sched_class_highest, NULL)
for_class_range(class, sched_class_highest, sched_class_lowest)
extern const struct sched_class stop_sched_class;
extern const struct sched_class dl_sched_class;