ptrace: revert "Prepare to fix racy accesses on task breakpoints"
authorOleg Nesterov <oleg@redhat.com>
Mon, 8 Jul 2013 23:00:54 +0000 (16:00 -0700)
committerLinus Torvalds <torvalds@linux-foundation.org>
Tue, 9 Jul 2013 17:33:26 +0000 (10:33 -0700)
This reverts commit bf26c018490c ("Prepare to fix racy accesses on task
breakpoints").

The patch was fine but we can no longer race with SIGKILL after commit
9899d11f6544 ("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>
include/linux/ptrace.h
include/linux/sched.h
kernel/exit.c
kernel/ptrace.c

index 89573a33ab3c43ee84cf629d84e5ff3d7f091206..07d0df6bf7687064c0b328dbb316694faa7442cf 100644 (file)
@@ -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
index cdd5407b37e27ea14fdabad7becf8607a7d0e976..75324d8157e3ff601f390de149bfe491ca77d007 100644 (file)
@@ -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
index fafe75d9e6f6fdfc0bab7ff7104d7e2ad97199ca..a949819055d51d5d4335544f81016770af6b687e 100644 (file)
@@ -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
index ba5e6cea181afecb583d567c38c23008142567c9..a146ee327f6ac15029b64424f0abd07e8d316f67 100644 (file)
@@ -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 */