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ptrace: revert "Prepare to fix racy accesses on task breakpoints" 

This reverts commit bf26c01849 ("Prepare to fix racy accesses on task
breakpoints").

The patch was fine but we can no longer race with SIGKILL after commit
9899d11f65 ("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 <oleg@redhat.com>
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
Acked-by: Michael 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: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Oleg Nesterov 2013-07-08 16:00:54 -07:00 committed by syphyr
parent 3d5d221acc
commit a8822b0e86
4 changed files with 1 additions and 30 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

10
include/linux/ptrace.h
View File

@ -196,9 +196,6 @@ 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;
@ -408,11 +405,4 @@ 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

3
include/linux/sched.h
View File

@ -1623,9 +1623,6 @@ struct task_struct {
unsigned int may_oom:1;
} memcg_oom;
#endif
#ifdef CONFIG_HAVE_HW_BREAKPOINT
atomic_t ptrace_bp_refcnt;
#endif
#ifdef CONFIG_UPROBES
struct uprobe_task *utask;
#endif

2
kernel/exit.c
View File

@ -786,7 +786,7 @@ 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);
proc_exit_connector(tsk);

16
kernel/ptrace.c
View File

@ -1253,19 +1253,3 @@ 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 */