diff options
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 | |
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>
-rw-r--r-- | kernel/sched/deadline.c | 4 | ||||
-rw-r--r-- | kernel/sched/fair.c | 4 | ||||
-rw-r--r-- | kernel/sched/idle.c | 4 | ||||
-rw-r--r-- | kernel/sched/rt.c | 4 | ||||
-rw-r--r-- | kernel/sched/sched.h | 17 | ||||
-rw-r--r-- | kernel/sched/stop_task.c | 3 |
6 files changed, 24 insertions, 12 deletions
diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c index 0b45dd1068f7..c6ce90fbb7ac 100644 --- a/kernel/sched/deadline.c +++ b/kernel/sched/deadline.c @@ -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, diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index cd9a37c0601b..f30d35a43f73 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -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, diff --git a/kernel/sched/idle.c b/kernel/sched/idle.c index 846743e39b3c..9da69c4e0ee9 100644 --- a/kernel/sched/idle.c +++ b/kernel/sched/idle.c @@ -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: */ diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c index 8a3b1ba09253..9b27352e0c1b 100644 --- a/kernel/sched/rt.c +++ b/kernel/sched/rt.c @@ -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, 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[]; diff --git a/kernel/sched/stop_task.c b/kernel/sched/stop_task.c index ceb5b6b12561..91bb10cc070e 100644 --- a/kernel/sched/stop_task.c +++ b/kernel/sched/stop_task.c @@ -109,8 +109,7 @@ static void update_curr_stop(struct rq *rq) /* * Simple, special scheduling class for the per-CPU stop tasks: */ -const struct sched_class stop_sched_class - __section("__stop_sched_class") = { +DEFINE_SCHED_CLASS(stop) = { .enqueue_task = enqueue_task_stop, .dequeue_task = dequeue_task_stop, |