Commit 7c8df286 authored by Oleg Nesterov's avatar Oleg Nesterov Committed by Linus Torvalds

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
......@@ -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
......@@ -1401,9 +1401,6 @@ 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
......
......@@ -808,7 +808,7 @@ 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
......
......@@ -1221,19 +1221,3 @@ 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 */
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