Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 06b7bcd8 authored by Oleg Nesterov's avatar Oleg Nesterov
Browse files

uprobes: Introduce uprobe_is_active() 



The lifetime of uprobe->rb_node and uprobe->inode is not refcounted,
delete_uprobe() is called when we detect that uprobe has no consumers,
and it would be deadly wrong to do this twice.

Change delete_uprobe() to WARN() if it was already called. We use
RB_CLEAR_NODE() to mark uprobe "inactive", then RB_EMPTY_NODE() can
be used to detect this case.

RB_EMPTY_NODE() is not used directly, we add the trivial helper for
the next change.

Signed-off-by: default avatarOleg Nesterov <oleg@redhat.com>
Acked-by: default avatarAnton Arapov <anton@redhat.com>
Acked-by: default avatarSrikar Dronamraju <srikar@linux.vnet.ibm.com>
parent 441f1eb7

kernel/events/uprobes.c

+8 −0
Original line number Original line Diff line number Diff line
@@ -669,6 +669,10 @@ remove_breakpoint(struct uprobe *uprobe, struct mm_struct *mm, unsigned long vad 
	return set_orig_insn(&uprobe->arch, mm, vaddr);

	return set_orig_insn(&uprobe->arch, mm, vaddr);

}

}





static inline bool uprobe_is_active(struct uprobe *uprobe)

{

	return !RB_EMPTY_NODE(&uprobe->rb_node);

}

/*

/*

 * There could be threads that have already hit the breakpoint. They

 * There could be threads that have already hit the breakpoint. They

 * will recheck the current insn and restart if find_uprobe() fails.

 * will recheck the current insn and restart if find_uprobe() fails.
@@ -676,9 +680,13 @@ remove_breakpoint(struct uprobe *uprobe, struct mm_struct *mm, unsigned long vad 
 */

 */

static void delete_uprobe(struct uprobe *uprobe)

static void delete_uprobe(struct uprobe *uprobe)

{

{

	if (WARN_ON(!uprobe_is_active(uprobe)))

		return;



	spin_lock(&uprobes_treelock);

	spin_lock(&uprobes_treelock);

	rb_erase(&uprobe->rb_node, &uprobes_tree);

	rb_erase(&uprobe->rb_node, &uprobes_tree);

	spin_unlock(&uprobes_treelock);

	spin_unlock(&uprobes_treelock);

	RB_CLEAR_NODE(&uprobe->rb_node); /* for uprobe_is_active() */

	iput(uprobe->inode);

	iput(uprobe->inode);

	put_uprobe(uprobe);

	put_uprobe(uprobe);

}

}