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profiling: Implement a simple task exit notifier when disabled

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Some kernel code currently depends on the profiling subsystem solely for
its task exit notifier. The rest of the profiling subsystem is left
unused.

Add a simple task exit notifier implemented in kernel/exit.c to make
such code work properly even when profiling is disabled. This will allow
unnecessary profiling code to be disabled without breakage.

Signed-off-by: Danny Lin <danny@kdrag0n.dev>
This commit is contained in:
Danny Lin 2019-04-07 23:34:36 -07:00 committed by spakkkk
parent c03e3c60c3
commit c4200b8164
2 changed files with 32 additions and 17 deletions
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23
include/linux/profile.h
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@ -67,9 +67,6 @@ static inline void profile_hit(int type, void *ip)
struct task_struct;
struct mm_struct;
/* task is in do_exit() */
void profile_task_exit(struct task_struct * task);
/* task is dead, free task struct ? Returns 1 if
* the task was taken, 0 if the task should be freed.
*/
@ -81,9 +78,6 @@ void profile_munmap(unsigned long addr);
int task_handoff_register(struct notifier_block * n);
int task_handoff_unregister(struct notifier_block * n);
int profile_event_register(enum profile_type, struct notifier_block * n);
int profile_event_unregister(enum profile_type, struct notifier_block * n);
struct pt_regs;
#else
@ -120,20 +114,15 @@ static inline int task_handoff_unregister(struct notifier_block * n)
return -ENOSYS;
}
static inline int profile_event_register(enum profile_type t, struct notifier_block * n)
{
return -ENOSYS;
}
static inline int profile_event_unregister(enum profile_type t, struct notifier_block * n)
{
return -ENOSYS;
}
#define profile_task_exit(a) do { } while (0)
#define profile_handoff_task(a) (0)
#define profile_munmap(a) do { } while (0)
#endif /* CONFIG_PROFILING */
/* task is in do_exit() */
void profile_task_exit(struct task_struct * task);
int profile_event_register(enum profile_type, struct notifier_block * n);
int profile_event_unregister(enum profile_type, struct notifier_block * n);
#endif /* _LINUX_PROFILE_H */

26
kernel/exit.c
View File

@ -776,6 +776,32 @@ static void check_stack_usage(void)
static inline void check_stack_usage(void) {}
#endif
#ifndef CONFIG_PROFILING
static BLOCKING_NOTIFIER_HEAD(task_exit_notifier);
int profile_event_register(enum profile_type t, struct notifier_block *n)
{
if (t == PROFILE_TASK_EXIT)
return blocking_notifier_chain_register(&task_exit_notifier, n);
return -ENOSYS;
}
int profile_event_unregister(enum profile_type t, struct notifier_block *n)
{
if (t == PROFILE_TASK_EXIT)
return blocking_notifier_chain_unregister(&task_exit_notifier,
n);
return -ENOSYS;
}
void profile_task_exit(struct task_struct *tsk)
{
blocking_notifier_call_chain(&task_exit_notifier, 0, tsk);
}
#endif
void __noreturn do_exit(long code)
{
struct task_struct *tsk = current;