sched: Remove struct sched_class::next field

Now that the sched_class descriptors are defined in order via the linker
script vmlinux.lds.h, there's no reason to have a "next" pointer to the
previous priroity structure. The order of the sturctures can be aligned as
an array, and used to index and find the next sched_class descriptor.

Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20191219214558.845353593@goodmis.org

diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
index d9e7946..c9cc1d6 100644 (file)
--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -2481,7 +2481,6 @@ static void prio_changed_dl(struct rq *rq, struct task_struct *p,
 
 const struct sched_class dl_sched_class
        __attribute__((section("__dl_sched_class"))) = {
-       .next                   = &rt_sched_class,
        .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 3365f6b..a63f400 100644 (file)
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -11124,7 +11124,6 @@ static unsigned int get_rr_interval_fair(struct rq *rq, struct task_struct *task
  */
 const struct sched_class fair_sched_class
        __attribute__((section("__fair_sched_class"))) = {
-       .next                   = &idle_sched_class,
        .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 f580629..336d478 100644 (file)
--- a/kernel/sched/idle.c
+++ b/kernel/sched/idle.c
@@ -455,7 +455,6 @@ static void update_curr_idle(struct rq *rq)
  */
 const struct sched_class idle_sched_class
        __attribute__((section("__idle_sched_class"))) = {
-       /* .next is NULL */
        /* 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 6543d44..f215eea 100644 (file)
--- a/kernel/sched/rt.c
+++ b/kernel/sched/rt.c
@@ -2431,7 +2431,6 @@ static unsigned int get_rr_interval_rt(struct rq *rq, struct task_struct *task)
 
 const struct sched_class rt_sched_class
        __attribute__((section("__rt_sched_class"))) = {
-       .next                   = &fair_sched_class,
        .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 4165c06..549e7e6 100644 (file)
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -1754,7 +1754,6 @@ extern const u32          sched_prio_to_wmult[40];
 #define RETRY_TASK             ((void *)-1UL)
 
 struct sched_class {
-       const struct sched_class *next;
 
 #ifdef CONFIG_UCLAMP_TASK
        int uclamp_enabled;

diff --git a/kernel/sched/stop_task.c b/kernel/sched/stop_task.c
index f4bbd54..394bc81 100644 (file)
--- a/kernel/sched/stop_task.c
+++ b/kernel/sched/stop_task.c
@@ -111,7 +111,6 @@ static void update_curr_stop(struct rq *rq)
  */
 const struct sched_class stop_sched_class
        __attribute__((section("__stop_sched_class"))) = {
-       .next                   = &dl_sched_class,
 
        .enqueue_task           = enqueue_task_stop,
        .dequeue_task           = dequeue_task_stop,