Commit c65eacbe authored by Andy Lutomirski's avatar Andy Lutomirski Committed by Ingo Molnar
Browse files

sched/core: Allow putting thread_info into task_struct



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: default avatarAndy 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: default avatarIngo Molnar <mingo@kernel.org>
parent d896fa20
......@@ -15,6 +15,8 @@
#include <net/net_namespace.h>
#include <linux/sched/rt.h>
#include <asm/thread_info.h>
#ifdef CONFIG_SMP
# define INIT_PUSHABLE_TASKS(tsk) \
.pushable_tasks = PLIST_NODE_INIT(tsk.pushable_tasks, MAX_PRIO),
......@@ -183,12 +185,19 @@ extern struct task_group root_task_group;
# define INIT_KASAN(tsk)
#endif
#ifdef CONFIG_THREAD_INFO_IN_TASK
# define INIT_TASK_TI(tsk) .thread_info = INIT_THREAD_INFO(tsk),
#else
# define INIT_TASK_TI(tsk)
#endif
/*
* INIT_TASK is used to set up the first task table, touch at
* your own risk!. Base=0, limit=0x1fffff (=2MB)
*/
#define INIT_TASK(tsk) \
{ \
INIT_TASK_TI(tsk) \
.state = 0, \
.stack = init_stack, \
.usage = ATOMIC_INIT(2), \
......
......@@ -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)
......
......@@ -13,6 +13,21 @@
struct timespec;
struct compat_timespec;
#ifdef CONFIG_THREAD_INFO_IN_TASK
struct thread_info {
u32 flags; /* low level flags */
};
#define INIT_THREAD_INFO(tsk) \
{ \
.flags = 0, \
}
#endif
#ifdef CONFIG_THREAD_INFO_IN_TASK
#define current_thread_info() ((struct thread_info *)current)
#endif
/*
* System call restart block.
*/
......
......@@ -26,6 +26,13 @@ config IRQ_WORK
config BUILDTIME_EXTABLE_SORT
bool
config THREAD_INFO_IN_TASK
bool
help
Select this to move thread_info off the stack into task_struct. To
make this work, an arch will need to remove all thread_info fields
except flags and fix any runtime bugs.
menu "General setup"
config BROKEN
......
......@@ -22,5 +22,8 @@ EXPORT_SYMBOL(init_task);
* Initial thread structure. Alignment of this is handled by a special
* linker map entry.
*/
union thread_union init_thread_union __init_task_data =
{ INIT_THREAD_INFO(init_task) };
union thread_union init_thread_union __init_task_data = {
#ifndef CONFIG_THREAD_INFO_IN_TASK
INIT_THREAD_INFO(init_task)
#endif
};
......@@ -1000,7 +1000,11 @@ static inline void __set_task_cpu(struct task_struct *p, unsigned int cpu)
* per-task data have been completed by this moment.
*/
smp_wmb();
#ifdef CONFIG_THREAD_INFO_IN_TASK
p->cpu = cpu;
#else
task_thread_info(p)->cpu = cpu;
#endif
p->wake_cpu = cpu;
#endif
}
......
Markdown is supported
0% or .
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment