uprobes: Change the callsite of uprobe_copy_process() (b68e0749) · Commits · 戴 / test

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:

Oleg Nesterov <oleg@redhat.com> Acked-by:

Srikar Dronamraju <srikar@linux.vnet.ibm.com>

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;

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