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Message-ID: <20090530223841.GA30514@redhat.com>
Date: Sun, 31 May 2009 00:38:41 +0200
From: Oleg Nesterov <oleg@...hat.com>
To: Roland McGrath <roland@...hat.com>
Cc: Christoph Hellwig <hch@...radead.org>, Ingo Molnar <mingo@...e.hu>,
linux-kernel@...r.kernel.org
Subject: [RFC PATCH 09/12 v3] ptrace: introduce ptrace_tracer() helper
Introduce ptrace_tracer() to simplify/cleanup the code which needs the
tracer and checks task_ptrace(). From now nobody else uses ->tracer
except ptrace_link/ptrace_unlink.
Signed-off-by: Oleg Nesterov <oleg@...hat.com>
---
include/linux/ptrace.h | 17 ++++++++++++-----
kernel/ptrace.c | 2 +-
kernel/signal.c | 20 +++++++++-----------
3 files changed, 22 insertions(+), 17 deletions(-)
--- PTRACE/include/linux/ptrace.h~09_PT_TRACER 2009-05-30 23:32:47.000000000 +0200
+++ PTRACE/include/linux/ptrace.h 2009-05-30 23:50:49.000000000 +0200
@@ -119,10 +119,17 @@ static inline int task_ptrace(struct tas
task->ptrace_ctx->flags : 0;
}
-static inline int ptrace_reparented(struct task_struct *child)
+static inline struct task_struct *ptrace_tracer(struct task_struct *task)
{
- return unlikely(task_ptrace(child)) &&
- child->ptrace_ctx->tracer != child->real_parent;
+ if (task->ptrace_ctx)
+ return task->ptrace_ctx->tracer;
+ return NULL;
+}
+
+static inline bool ptrace_reparented(struct task_struct *child)
+{
+ struct task_struct *tracer = ptrace_tracer(child);
+ return unlikely(tracer) && tracer != child->real_parent;
}
static inline void ptrace_unlink(struct task_struct *child)
@@ -170,9 +177,9 @@ static inline void ptrace_init_task(stru
INIT_LIST_HEAD(&child->ptrace_entry);
INIT_LIST_HEAD(&child->ptraced);
- if (unlikely(child->ptrace_ctx) && task_ptrace(current))
+ if (unlikely(child->ptrace_ctx) && ptrace_tracer(current))
ptrace_link(child, task_ptrace(current),
- current->ptrace_ctx->tracer);
+ ptrace_tracer(current));
}
/**
--- PTRACE/kernel/ptrace.c~09_PT_TRACER 2009-05-30 23:32:47.000000000 +0200
+++ PTRACE/kernel/ptrace.c 2009-05-30 23:55:26.000000000 +0200
@@ -108,7 +108,7 @@ int ptrace_check_attach(struct task_stru
* be changed by us so it's not changing right after this.
*/
read_lock(&tasklist_lock);
- if (task_ptrace(child) && child->ptrace_ctx->tracer == current) {
+ if (ptrace_tracer(child) == current) {
ret = 0;
/*
* child->sighand can't be NULL, release_task()
--- PTRACE/kernel/signal.c~09_PT_TRACER 2009-05-30 23:32:47.000000000 +0200
+++ PTRACE/kernel/signal.c 2009-05-30 23:50:49.000000000 +0200
@@ -1411,10 +1411,7 @@ int do_notify_parent(struct task_struct
BUG_ON(!task_ptrace(tsk) &&
(tsk->group_leader != tsk || !thread_group_empty(tsk)));
- if (task_ptrace(tsk))
- parent = tsk->ptrace_ctx->tracer;
- else
- parent = tsk->real_parent;
+ parent = ptrace_tracer(tsk) ?: tsk->real_parent;
info.si_signo = sig;
info.si_errno = 0;
@@ -1489,9 +1486,8 @@ static void do_notify_parent_cldstop(str
struct task_struct *parent;
struct sighand_struct *sighand;
- if (task_ptrace(tsk))
- parent = tsk->ptrace_ctx->tracer;
- else {
+ parent = ptrace_tracer(tsk);
+ if (likely(!parent)) {
tsk = tsk->group_leader;
parent = tsk->real_parent;
}
@@ -1538,7 +1534,9 @@ static void do_notify_parent_cldstop(str
static inline int may_ptrace_stop(void)
{
- if (!likely(task_ptrace(current)))
+ struct task_struct *tracer = ptrace_tracer(current);
+
+ if (!likely(tracer))
return 0;
/*
* Are we in the middle of do_coredump?
@@ -1550,7 +1548,7 @@ static inline int may_ptrace_stop(void)
* is safe to enter schedule().
*/
if (unlikely(current->mm->core_state) &&
- unlikely(current->mm == current->ptrace_ctx->tracer->mm))
+ unlikely(current->mm == tracer->mm))
return 0;
return 1;
@@ -1783,8 +1781,8 @@ static int ptrace_signal(int signr, sigi
info->si_code = SI_USER;
rcu_read_lock();
- tracer = current->ptrace_ctx->tracer;
- if (task_ptrace(current)) {
+ tracer = ptrace_tracer(current);
+ if (likely(tracer)) {
info->si_pid = task_pid_vnr(tracer);
info->si_uid = task_uid(tracer);
} else {
--
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