Messages in this thread | | | Date | Wed, 2 Jan 2013 13:57:12 +0100 | From | Anton Arapov <> | Subject | Re: [PATCH 2/3] uprobes: Introduce uprobe_is_active() |
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On Sun, Nov 25, 2012 at 11:33:47PM +0100, Oleg Nesterov wrote: > 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: Oleg Nesterov <oleg@redhat.com> > --- > kernel/events/uprobes.c | 8 ++++++++ > 1 files changed, 8 insertions(+), 0 deletions(-)
Acked-by: Anton Arapov <anton@redhat.com>
> diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c > index 53dc2eb..2886c82 100644 > --- a/kernel/events/uprobes.c > +++ b/kernel/events/uprobes.c > @@ -669,6 +669,10 @@ remove_breakpoint(struct uprobe *uprobe, struct mm_struct *mm, unsigned long vad > 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 > * 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) > { > + if (WARN_ON(!uprobe_is_active(uprobe))) > + return; > + > spin_lock(&uprobes_treelock); > rb_erase(&uprobe->rb_node, &uprobes_tree); > spin_unlock(&uprobes_treelock); > + RB_CLEAR_NODE(&uprobe->rb_node); /* for uprobe_is_active() */ > iput(uprobe->inode); > put_uprobe(uprobe); > } > -- > 1.5.5.1 >
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