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| author | Peter Zijlstra <peterz@infradead.org> | 2020-10-21 15:45:33 +0200 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2020-10-29 11:00:32 +0100 |
| commit | 43c31ac0e665d942fcaba83a725a8b1aeeb7adf0 (patch) | |
| tree | 44e9276309d8c428388a148ec5ce6c7a212dfecd /kernel/sched/sched.h | |
| parent | 345a957fcc95630bf5535d7668a59ed983eb49a7 (diff) | |
| download | linux-43c31ac0e665d942fcaba83a725a8b1aeeb7adf0.tar.bz2 | |
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: 85c2ce9104eb ("sched, vmlinux.lds: Increase STRUCT_ALIGNMENT to 64 bytes for GCC-4.9")
Reported-by: Florian Fainelli <f.fainelli@gmail.com>
Suggested-by: Jakub Jelinek <jakub@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Diffstat (limited to 'kernel/sched/sched.h')
| -rw-r--r-- | kernel/sched/sched.h | 17 |
1 files changed, 15 insertions, 2 deletions
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index 965b2968c13a..3e45055efbc5 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -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[]; |