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Message-ID: <20090528113550.GA18702@redhat.com>
Date: Thu, 28 May 2009 13:35:50 +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 6/12 v2] ptrace: mv task_struct->ptrace
ptrace_ctx->flags, kill ptrace_link()
Move task_struct->ptrace into ptrace_ctx->flags and change the users
accordingly.
Also, kill ptrace_link(). The only caller is ptrace_init_task(), and with
the recent changes we can check "is it traced" earlier, because ->flags
was already initialized by alloc_ptrace_context().
include/linux/sched.h | 1 -
include/linux/ptrace.h | 24 +++++++++---------------
kernel/ptrace.c | 16 ++++++++--------
3 files changed, 17 insertions(+), 24 deletions(-)
--- PTRACE/include/linux/sched.h~5_MV_FLAGS 2009-05-28 07:26:35.000000000 +0200
+++ PTRACE/include/linux/sched.h 2009-05-28 08:23:13.000000000 +0200
@@ -1119,7 +1119,6 @@ struct task_struct {
void *stack;
atomic_t usage;
unsigned int flags; /* per process flags, defined below */
- unsigned int ptrace;
int lock_depth; /* BKL lock depth */
--- PTRACE/include/linux/ptrace.h~5_MV_FLAGS 2009-05-28 08:19:16.000000000 +0200
+++ PTRACE/include/linux/ptrace.h 2009-05-28 08:29:11.000000000 +0200
@@ -51,10 +51,6 @@
#ifdef __KERNEL__
/*
* Ptrace flags
- *
- * The owner ship rules for task->ptrace which holds the ptrace
- * flags is simple. When a task is running it owns it's task->ptrace
- * flags. When the a task is stopped the ptracer owns task->ptrace.
*/
#define PT_PTRACED 0x00000001
@@ -80,6 +76,7 @@
#include <linux/sched.h> /* For struct task_struct. */
struct ptrace_context {
+ unsigned long flags;
};
extern int alloc_ptrace_context(struct task_struct *child);
@@ -116,18 +113,16 @@ static inline int ptrace_reparented(stru
* @task: pointer to &task_struct in question
*
* Returns the %PT_* flags that apply to @task.
+ *
+ * Once allocated, ->ptrace_ctx is never freed until @task is freed,
+ * so this access is always safe.
*/
static inline int task_ptrace(struct task_struct *task)
{
- return task->ptrace;
+ return unlikely(task->ptrace_ctx) ?
+ task->ptrace_ctx->flags : 0;
}
-static inline void ptrace_link(struct task_struct *child,
- struct task_struct *new_parent)
-{
- if (unlikely(task_ptrace(child)))
- __ptrace_link(child, new_parent);
-}
static inline void ptrace_unlink(struct task_struct *child)
{
if (unlikely(task_ptrace(child)))
@@ -173,10 +168,9 @@ static inline void ptrace_init_task(stru
INIT_LIST_HEAD(&child->ptrace_entry);
INIT_LIST_HEAD(&child->ptraced);
child->parent = child->real_parent;
- child->ptrace = 0;
- if (unlikely(child->ptrace_ctx)) {
- child->ptrace = current->ptrace;
- ptrace_link(child, current->parent);
+ if (unlikely(child->ptrace_ctx) && task_ptrace(current)) {
+ child->ptrace_ctx->flags = task_ptrace(current);
+ __ptrace_link(child, current->parent);
}
}
--- PTRACE/kernel/ptrace.c~5_MV_FLAGS 2009-05-28 08:09:47.000000000 +0200
+++ PTRACE/kernel/ptrace.c 2009-05-28 08:23:13.000000000 +0200
@@ -81,7 +81,7 @@ void __ptrace_unlink(struct task_struct
{
BUG_ON(!task_ptrace(child));
- child->ptrace = 0;
+ child->ptrace_ctx->flags = 0;
child->parent = child->real_parent;
list_del_init(&child->ptrace_entry);
@@ -236,9 +236,9 @@ int ptrace_attach(struct task_struct *ta
if (task_ptrace(task))
goto unlock_tasklist;
- task->ptrace = PT_PTRACED;
+ task->ptrace_ctx->flags = PT_PTRACED;
if (capable(CAP_SYS_PTRACE))
- task->ptrace |= PT_PTRACE_CAP;
+ task->ptrace_ctx->flags |= PT_PTRACE_CAP;
__ptrace_link(task, current);
send_sig_info(SIGSTOP, SEND_SIG_FORCED, task);
@@ -276,7 +276,7 @@ int ptrace_traceme(void)
* pretend ->real_parent untraces us right after return.
*/
if (!ret && !(current->real_parent->flags & PF_EXITING)) {
- current->ptrace = PT_PTRACED;
+ current->ptrace_ctx->flags = PT_PTRACED;
__ptrace_link(current, current->real_parent);
}
}
@@ -434,7 +434,7 @@ int ptrace_writedata(struct task_struct
return copied;
}
-static int ptrace_setoptions(struct task_struct *child, long data)
+static int ptrace_setoptions(struct ptrace_context *ptrace_ctx, long data)
{
unsigned int new_flags = 0;
@@ -459,8 +459,8 @@ static int ptrace_setoptions(struct task
if (data & PTRACE_O_TRACEEXIT)
new_flags |= PT_TRACE_EXIT;
- child->ptrace &= ~PT_TRACE_MASK;
- child->ptrace |= new_flags;
+ ptrace_ctx->flags &= ~PT_TRACE_MASK;
+ ptrace_ctx->flags |= new_flags;
return (data & ~PTRACE_O_MASK) ? -EINVAL : 0;
}
@@ -572,7 +572,7 @@ int ptrace_request(struct task_struct *c
case PTRACE_OLDSETOPTIONS:
#endif
case PTRACE_SETOPTIONS:
- ret = ptrace_setoptions(child, data);
+ ret = ptrace_setoptions(child->ptrace_ctx, data);
break;
case PTRACE_GETEVENTMSG:
ret = put_user(child->ptrace_message, (unsigned long __user *) data);
--
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