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sched/core: Allow putting thread_info into task_struct

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If an arch opts in by setting CONFIG_THREAD_INFO_IN_TASK_STRUCT,
then thread_info is defined as a single 'u32 flags' and is the first
entry of task_struct.  thread_info::task is removed (it serves no
purpose if thread_info is embedded in task_struct), and
thread_info::cpu gets its own slot in task_struct.

This is heavily based on a patch written by Linus.

Originally-from: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Jann Horn <jann@thejh.net>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/a0898196f0476195ca02713691a5037a14f2aac5.1473801993.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Andy Lutomirski
2016-09-13 14:29:24 -07:00
committed by Ingo Molnar
parent d896fa20a7
commit c65eacbe29
6 changed files with 74 additions and 4 deletions
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36
include/linux/sched.h
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@@ -1458,6 +1458,13 @@ struct tlbflush_unmap_batch {
};
struct task_struct {
#ifdef CONFIG_THREAD_INFO_IN_TASK
/*
* For reasons of header soup (see current_thread_info()), this
* must be the first element of task_struct.
*/
struct thread_info thread_info;
#endif
volatile long state; /* -1 unrunnable, 0 runnable, >0 stopped */
void *stack;
atomic_t usage;
@@ -1467,6 +1474,9 @@ struct task_struct {
#ifdef CONFIG_SMP
struct llist_node wake_entry;
int on_cpu;
#ifdef CONFIG_THREAD_INFO_IN_TASK
unsigned int cpu; /* current CPU */
#endif
unsigned int wakee_flips;
unsigned long wakee_flip_decay_ts;
struct task_struct *last_wakee;
@@ -2588,7 +2598,9 @@ extern void set_curr_task(int cpu, struct task_struct *p);
void yield(void);
union thread_union {
#ifndef CONFIG_THREAD_INFO_IN_TASK
struct thread_info thread_info;
#endif
unsigned long stack[THREAD_SIZE/sizeof(long)];
};
@@ -3076,10 +3088,26 @@ static inline void threadgroup_change_end(struct task_struct *tsk)
cgroup_threadgroup_change_end(tsk);
}
#ifndef __HAVE_THREAD_FUNCTIONS
#ifdef CONFIG_THREAD_INFO_IN_TASK
static inline struct thread_info *task_thread_info(struct task_struct *task)
{
return &task->thread_info;
}
static inline void *task_stack_page(const struct task_struct *task)
{
return task->stack;
}
#define setup_thread_stack(new,old) do { } while(0)
static inline unsigned long *end_of_stack(const struct task_struct *task)
{
return task->stack;
}
#elif !defined(__HAVE_THREAD_FUNCTIONS)
#define task_thread_info(task) ((struct thread_info *)(task)->stack)
#define task_stack_page(task) ((task)->stack)
#define task_stack_page(task) ((void *)(task)->stack)
static inline void setup_thread_stack(struct task_struct *p, struct task_struct *org)
{
@@ -3379,7 +3407,11 @@ static inline void ptrace_signal_wake_up(struct task_struct *t, bool resume)
static inline unsigned int task_cpu(const struct task_struct *p)
{
#ifdef CONFIG_THREAD_INFO_IN_TASK
return p->cpu;
#else
return task_thread_info(p)->cpu;
#endif
}
static inline int task_node(const struct task_struct *p)