Commit 43c31ac0 authored by Peter Zijlstra's avatar Peter Zijlstra
Browse files

sched: Remove relyance on STRUCT_ALIGNMENT 



Florian reported that all of kernel/sched/ is rebuild when
CONFIG_BLK_DEV_INITRD is changed, which, while not a bug is
unexpected. This is due to us including vmlinux.lds.h.

Jakub explained that the problem is that we put the alignment
requirement on the type instead of on a variable. Type alignment is a
minimum, the compiler is free to pick any larger alignment for a
specific instance of the type (eg. the variable).

So force the type alignment on all individual variable definitions and
remove the undesired dependency on vmlinux.lds.h.

Fixes: 85c2ce91 ("sched, vmlinux.lds: Increase STRUCT_ALIGNMENT to 64 bytes for GCC-4.9")
Reported-by: default avatarFlorian Fainelli <f.fainelli@gmail.com>
Suggested-by: default avatarJakub Jelinek <jakub@redhat.com>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
parent 345a957f

kernel/sched/deadline.c

+2 −2
Original line number Diff line number Diff line
@@ -2522,8 +2522,8 @@ static void prio_changed_dl(struct rq *rq, struct task_struct *p, 
	}

}



const struct sched_class dl_sched_class

	__section("__dl_sched_class") = {

DEFINE_SCHED_CLASS(dl) = {



	.enqueue_task		= enqueue_task_dl,

	.dequeue_task		= dequeue_task_dl,

	.yield_task		= yield_task_dl,

kernel/sched/fair.c

+2 −2
Original line number Diff line number Diff line
@@ -11171,8 +11171,8 @@ static unsigned int get_rr_interval_fair(struct rq *rq, struct task_struct *task 
/*

 * All the scheduling class methods:

 */

const struct sched_class fair_sched_class

	__section("__fair_sched_class") = {

DEFINE_SCHED_CLASS(fair) = {



	.enqueue_task		= enqueue_task_fair,

	.dequeue_task		= dequeue_task_fair,

	.yield_task		= yield_task_fair,

kernel/sched/idle.c

+2 −2
Original line number Diff line number Diff line
@@ -458,8 +458,8 @@ static void update_curr_idle(struct rq *rq) 
/*

 * Simple, special scheduling class for the per-CPU idle tasks:

 */

const struct sched_class idle_sched_class

	__section("__idle_sched_class") = {

DEFINE_SCHED_CLASS(idle) = {



	/* no enqueue/yield_task for idle tasks */



	/* dequeue is not valid, we print a debug message there: */

kernel/sched/rt.c

+2 −2
Original line number Diff line number Diff line
@@ -2431,8 +2431,8 @@ static unsigned int get_rr_interval_rt(struct rq *rq, struct task_struct *task) 
		return 0;

}



const struct sched_class rt_sched_class

	__section("__rt_sched_class") = {

DEFINE_SCHED_CLASS(rt) = {



	.enqueue_task		= enqueue_task_rt,

	.dequeue_task		= dequeue_task_rt,

	.yield_task		= yield_task_rt,

kernel/sched/sched.h

+15 −2
Original line number Diff line number Diff line
@@ -67,7 +67,6 @@ 
#include <linux/tsacct_kern.h>



#include <asm/tlb.h>

#include <asm-generic/vmlinux.lds.h>



#ifdef CONFIG_PARAVIRT

# include <asm/paravirt.h>
@@ -1836,7 +1835,7 @@ struct sched_class { 
#ifdef CONFIG_FAIR_GROUP_SCHED

	void (*task_change_group)(struct task_struct *p, int type);

#endif

} __aligned(STRUCT_ALIGNMENT); /* STRUCT_ALIGN(), vmlinux.lds.h */

};



static inline void put_prev_task(struct rq *rq, struct task_struct *prev)

{
@@ -1850,6 +1849,20 @@ static inline void set_next_task(struct rq *rq, struct task_struct *next) 
	next->sched_class->set_next_task(rq, next, false);

}





/*

 * Helper to define a sched_class instance; each one is placed in a separate

 * section which is ordered by the linker script:

 *

 *   include/asm-generic/vmlinux.lds.h

 *

 * Also enforce alignment on the instance, not the type, to guarantee layout.

 */

#define DEFINE_SCHED_CLASS(name) \

const struct sched_class name##_sched_class \

	__aligned(__alignof__(struct sched_class)) \

	__section("__" #name "_sched_class")



/* Defined in include/asm-generic/vmlinux.lds.h */

extern struct sched_class __begin_sched_classes[];

extern struct sched_class __end_sched_classes[];

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