Re: [PATCH 01/17] exit: Remove profile_task_exit & profile_munmap
From: Al Viro <viro@zeniv.linux.org.uk>
Date: 2022-01-07 03:48:22
Also in:
linux-arch, lkml
Subsystem:
exec & binfmt api, elf, memory management, memory management - core, memory mapping, scheduler, the rest · Maintainers:
Kees Cook, Andrew Morton, David Hildenbrand, Liam R. Howlett, Lorenzo Stoakes, Ingo Molnar, Peter Zijlstra, Juri Lelli, Vincent Guittot, Linus Torvalds
Possibly related (same subject, not in this thread)
- 2022-01-08 · Re: [PATCH 01/17] exit: Remove profile_task_exit & profile_munmap · Eric W. Biederman <hidden>
On Mon, Jan 03, 2022 at 03:32:56PM -0600, Eric W. Biederman wrote:
When I say remove I mean remove. All profile_task_exit and profile_munmap do is call a blocking notifier chain. The helpers profile_task_register and profile_task_unregister are not called anywhere in the tree. Which means this is all dead code. So remove the dead code and make it easier to read do_exit.
How about doing the same to profile_handoff_task() and task_handoff_register()/task_handoff_unregister(), while we are at it? Combined diff would be this:
diff --git a/include/linux/profile.h b/include/linux/profile.h
index fd18ca96f5574..6aa64730298a0 100644
--- a/include/linux/profile.h
+++ b/include/linux/profile.h@@ -31,11 +31,6 @@ static inline int create_proc_profile(void) } #endif -enum profile_type { - PROFILE_TASK_EXIT, - PROFILE_MUNMAP -}; - #ifdef CONFIG_PROFILING extern int prof_on __read_mostly;
@@ -63,26 +58,6 @@ static inline void profile_hit(int type, void *ip) profile_hits(type, ip, 1); } -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. - */ -int profile_handoff_task(struct task_struct * task); - -/* sys_munmap */ -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); - #else #define prof_on 0
@@ -107,30 +82,6 @@ static inline void profile_hit(int type, void *ip) return; } -static inline int task_handoff_register(struct notifier_block * n) -{ - return -ENOSYS; -} - -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 */ #endif /* _LINUX_PROFILE_H */
diff --git a/kernel/exit.c b/kernel/exit.c
index f702a6a63686e..5086a5e9d02de 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c@@ -765,7 +765,6 @@ void __noreturn do_exit(long code) preempt_count_set(PREEMPT_ENABLED); } - profile_task_exit(tsk); kcov_task_exit(tsk); coredump_task_exit(tsk);
diff --git a/kernel/fork.c b/kernel/fork.c
index 3244cc56b697d..496c0b6c8cb83 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c@@ -754,9 +754,7 @@ void __put_task_struct(struct task_struct *tsk) delayacct_tsk_free(tsk); put_signal_struct(tsk->signal); sched_core_free(tsk); - - if (!profile_handoff_task(tsk)) - free_task(tsk); + free_task(tsk); } EXPORT_SYMBOL_GPL(__put_task_struct);
diff --git a/kernel/profile.c b/kernel/profile.c
index eb9c7f0f5ac52..37640a0bd8a3c 100644
--- a/kernel/profile.c
+++ b/kernel/profile.c@@ -133,79 +133,6 @@ int __ref profile_init(void) return -ENOMEM; } -/* Profile event notifications */ - -static BLOCKING_NOTIFIER_HEAD(task_exit_notifier); -static ATOMIC_NOTIFIER_HEAD(task_free_notifier); -static BLOCKING_NOTIFIER_HEAD(munmap_notifier); - -void profile_task_exit(struct task_struct *task) -{ - blocking_notifier_call_chain(&task_exit_notifier, 0, task); -} - -int profile_handoff_task(struct task_struct *task) -{ - int ret; - ret = atomic_notifier_call_chain(&task_free_notifier, 0, task); - return (ret == NOTIFY_OK) ? 1 : 0; -} - -void profile_munmap(unsigned long addr) -{ - blocking_notifier_call_chain(&munmap_notifier, 0, (void *)addr); -} - -int task_handoff_register(struct notifier_block *n) -{ - return atomic_notifier_chain_register(&task_free_notifier, n); -} -EXPORT_SYMBOL_GPL(task_handoff_register); - -int task_handoff_unregister(struct notifier_block *n) -{ - return atomic_notifier_chain_unregister(&task_free_notifier, n); -} -EXPORT_SYMBOL_GPL(task_handoff_unregister); - -int profile_event_register(enum profile_type type, struct notifier_block *n) -{ - int err = -EINVAL; - - switch (type) { - case PROFILE_TASK_EXIT: - err = blocking_notifier_chain_register( - &task_exit_notifier, n); - break; - case PROFILE_MUNMAP: - err = blocking_notifier_chain_register( - &munmap_notifier, n); - break; - } - - return err; -} -EXPORT_SYMBOL_GPL(profile_event_register); - -int profile_event_unregister(enum profile_type type, struct notifier_block *n) -{ - int err = -EINVAL; - - switch (type) { - case PROFILE_TASK_EXIT: - err = blocking_notifier_chain_unregister( - &task_exit_notifier, n); - break; - case PROFILE_MUNMAP: - err = blocking_notifier_chain_unregister( - &munmap_notifier, n); - break; - } - - return err; -} -EXPORT_SYMBOL_GPL(profile_event_unregister); - #if defined(CONFIG_SMP) && defined(CONFIG_PROC_FS) /* * Each cpu has a pair of open-addressed hashtables for pending
diff --git a/mm/mmap.c b/mm/mmap.c
index bfb0ea164a90a..70318c2a47c39 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c@@ -2928,7 +2928,6 @@ EXPORT_SYMBOL(vm_munmap); SYSCALL_DEFINE2(munmap, unsigned long, addr, size_t, len) { addr = untagged_addr(addr); - profile_munmap(addr); return __vm_munmap(addr, len, true); }