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Commit b68e0749 authored by Oleg Nesterov's avatar Oleg Nesterov
Browse files

uprobes: Change the callsite of uprobe_copy_process() 



Preparation for the next patches.

Move the callsite of uprobe_copy_process() in copy_process() down
to the succesfull return. We do not care if copy_process() fails,
uprobe_free_utask() won't be called in this case so the wrong
->utask != NULL doesn't matter.

OTOH, with this change we know that copy_process() can't fail when
uprobe_copy_process() is called, the new task should either return
to user-mode or call do_exit(). This way uprobe_copy_process() can:

	1. setup p->utask != NULL if necessary

	2. setup uprobes_state.xol_area

	3. use task_work_add(p)

Also, move the definition of uprobe_copy_process() down so that it
can see get_utask().

Signed-off-by: default avatarOleg Nesterov <oleg@redhat.com>
Acked-by: default avatarSrikar Dronamraju <srikar@linux.vnet.ibm.com>
parent c2d3f25d

kernel/events/uprobes.c

+8 −8
Original line number Diff line number Diff line
@@ -1344,14 +1344,6 @@ void uprobe_free_utask(struct task_struct *t) 
	t->utask = NULL;

}



/*

 * Called in context of a new clone/fork from copy_process.

 */

void uprobe_copy_process(struct task_struct *t)

{

	t->utask = NULL;

}



/*

 * Allocate a uprobe_task object for the task if if necessary.

 * Called when the thread hits a breakpoint.
@@ -1367,6 +1359,14 @@ static struct uprobe_task *get_utask(void) 
	return current->utask;

}



/*

 * Called in context of a new clone/fork from copy_process.

 */

void uprobe_copy_process(struct task_struct *t)

{

	t->utask = NULL;

}



/*

 * Current area->vaddr notion assume the trampoline address is always

 * equal area->vaddr.

kernel/fork.c

+1 −1
Original line number Diff line number Diff line
@@ -1373,7 +1373,6 @@ static struct task_struct *copy_process(unsigned long clone_flags, 
	INIT_LIST_HEAD(&p->pi_state_list);

	p->pi_state_cache = NULL;

#endif

	uprobe_copy_process(p);

	/*

	 * sigaltstack should be cleared when sharing the same VM

	 */
@@ -1490,6 +1489,7 @@ static struct task_struct *copy_process(unsigned long clone_flags, 
	perf_event_fork(p);



	trace_task_newtask(p, clone_flags);

	uprobe_copy_process(p);



	return p;