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Commit 7c8df286 authored by Oleg Nesterov's avatar Oleg Nesterov Committed by Linus Torvalds
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ptrace: revert "Prepare to fix racy accesses on task breakpoints" 



This reverts commit bf26c018 ("Prepare to fix racy accesses on task
breakpoints").

The patch was fine but we can no longer race with SIGKILL after commit
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: default avatarOleg Nesterov <oleg@redhat.com>
Acked-by: default avatarFrederic Weisbecker <fweisbec@gmail.com>
Acked-by: default avatarMichael Neuling <mikey@neuling.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jan Kratochvil <jan.kratochvil@redhat.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Prasad <prasad@linux.vnet.ibm.com>
Cc: Russell King <linux@arm.linux.org.uk>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent e8c073c4

include/linux/ptrace.h

+0 −10
Original line number Original line Diff line number Diff line
@@ -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->ptrace_entry);

	INIT_LIST_HEAD(&child->ptraced);

	INIT_LIST_HEAD(&child->ptraced);

#ifdef CONFIG_HAVE_HW_BREAKPOINT

	atomic_set(&child->ptrace_bp_refcnt, 1);

#endif

	child->jobctl = 0;

	child->jobctl = 0;

	child->ptrace = 0;

	child->ptrace = 0;

	child->parent = child->real_parent;

	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 args[6], unsigned int maxargs,

				unsigned long *sp, unsigned long *pc);

				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
 
#endif

include/linux/sched.h

+0 −3
Original line number Original line Diff line number Diff line
@@ -1401,9 +1401,6 @@ struct task_struct { 
	} memcg_batch;

	} memcg_batch;

	unsigned int memcg_kmem_skip_account;

	unsigned int memcg_kmem_skip_account;

#endif

#endif

#ifdef CONFIG_HAVE_HW_BREAKPOINT

	atomic_t ptrace_bp_refcnt;

#endif

#ifdef CONFIG_UPROBES

#ifdef CONFIG_UPROBES

	struct uprobe_task *utask;

	struct uprobe_task *utask;

#endif

#endif

kernel/exit.c

+1 −1
Original line number Original line Diff line number Diff line
@@ -808,7 +808,7 @@ void do_exit(long code) 
	/*

	/*

	 * FIXME: do that only when needed, using sched_exit tracepoint

	 * FIXME: do that only when needed, using sched_exit tracepoint

	 */

	 */

	ptrace_put_breakpoints(tsk);

	flush_ptrace_hw_breakpoint(tsk);





	exit_notify(tsk, group_dead);

	exit_notify(tsk, group_dead);

#ifdef CONFIG_NUMA

#ifdef CONFIG_NUMA

kernel/ptrace.c

+0 −16
Original line number Original line Diff line number Diff line
@@ -1221,19 +1221,3 @@ asmlinkage long compat_sys_ptrace(compat_long_t request, compat_long_t pid, 
	return ret;

	return ret;

}

}

#endif	/* CONFIG_COMPAT */
 
#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 */