From: Oleg Nesterov Date: Sun, 25 Nov 2012 21:01:42 +0000 (+0100) Subject: uprobes: Introduce uprobe_is_active() X-Git-Tag: upstream/snapshot3+hdmi~5742^2~2^2~26 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=06b7bcd8cbd7eb1af331e437ec3d8f5182ae1b7e;p=platform%2Fadaptation%2Frenesas_rcar%2Frenesas_kernel.git 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: Oleg Nesterov Acked-by: Anton Arapov Acked-by: Srikar Dronamraju --- diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c index 5d38b40..358badd 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); }