From b84285bedcfdaa7a87bc8ecb1e3e872f65f39155 Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Fri, 28 Jun 2013 09:53:47 +1000 Subject: [PATCH] ptrace: revert "Prepare to fix racy accesses on task breakpoints" This reverts commit bf26c018490c2fce ("Prepare to fix racy accesses on task breakpoints"). The patch was fine but we can no longer race with SIGKILL after 9899d11f ("ptrace: ensure arch_ptrace/ptrace_request can never race with SIGKILL"), the __TASK_TRACED tracee can't be woken up and ->ptrace_bps[] can't go away. Now that ptrace_get_breakpoints/ptrace_put_breakpoints have no callers, we can kill them and remove task->ptrace_bp_refcnt. Signed-off-by: Oleg Nesterov Acked-by: Frederic Weisbecker Acked-by: Michael Neuling Cc: Benjamin Herrenschmidt Cc: Ingo Molnar Cc: Jan Kratochvil Cc: Paul Mackerras Cc: Paul Mundt Cc: Will Deacon Cc: Prasad Cc: Russell King Signed-off-by: Andrew Morton --- include/linux/ptrace.h | 10 ---------- include/linux/sched.h | 3 --- kernel/exit.c | 2 +- kernel/ptrace.c | 16 ---------------- 4 files changed, 1 insertion(+), 30 deletions(-) diff --git a/include/linux/ptrace.h b/include/linux/ptrace.h index 89573a33ab3c..07d0df6bf768 100644 --- a/include/linux/ptrace.h +++ b/include/linux/ptrace.h @@ -142,9 +142,6 @@ static inline void ptrace_init_task(struct task_struct *child, bool ptrace) { INIT_LIST_HEAD(&child->ptrace_entry); INIT_LIST_HEAD(&child->ptraced); -#ifdef CONFIG_HAVE_HW_BREAKPOINT - atomic_set(&child->ptrace_bp_refcnt, 1); -#endif child->jobctl = 0; child->ptrace = 0; child->parent = child->real_parent; @@ -351,11 +348,4 @@ extern int task_current_syscall(struct task_struct *target, long *callno, unsigned long args[6], unsigned int maxargs, unsigned long *sp, unsigned long *pc); -#ifdef CONFIG_HAVE_HW_BREAKPOINT -extern int ptrace_get_breakpoints(struct task_struct *tsk); -extern void ptrace_put_breakpoints(struct task_struct *tsk); -#else -static inline void ptrace_put_breakpoints(struct task_struct *tsk) { } -#endif /* CONFIG_HAVE_HW_BREAKPOINT */ - #endif diff --git a/include/linux/sched.h b/include/linux/sched.h index df64c7301ee7..6af2cc51ab1a 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1399,9 +1399,6 @@ struct task_struct { } memcg_batch; unsigned int memcg_kmem_skip_account; #endif -#ifdef CONFIG_HAVE_HW_BREAKPOINT - atomic_t ptrace_bp_refcnt; -#endif #ifdef CONFIG_UPROBES struct uprobe_task *utask; #endif diff --git a/kernel/exit.c b/kernel/exit.c index 6a057750ebbb..2f3be8b6904b 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -819,7 +819,7 @@ void do_exit(long code) /* * FIXME: do that only when needed, using sched_exit tracepoint */ - ptrace_put_breakpoints(tsk); + flush_ptrace_hw_breakpoint(tsk); exit_notify(tsk, group_dead); #ifdef CONFIG_NUMA diff --git a/kernel/ptrace.c b/kernel/ptrace.c index aed981a3f69c..8cc170b157d7 100644 --- a/kernel/ptrace.c +++ b/kernel/ptrace.c @@ -1179,19 +1179,3 @@ asmlinkage long compat_sys_ptrace(compat_long_t request, compat_long_t pid, return ret; } #endif /* CONFIG_COMPAT */ - -#ifdef CONFIG_HAVE_HW_BREAKPOINT -int ptrace_get_breakpoints(struct task_struct *tsk) -{ - if (atomic_inc_not_zero(&tsk->ptrace_bp_refcnt)) - return 0; - - return -1; -} - -void ptrace_put_breakpoints(struct task_struct *tsk) -{ - if (atomic_dec_and_test(&tsk->ptrace_bp_refcnt)) - flush_ptrace_hw_breakpoint(tsk); -} -#endif /* CONFIG_HAVE_HW_BREAKPOINT */ -- 2.39.5