Messages in this thread Patch in this message | | | From | Tejun Heo <> | Subject | [PATCH 10/25] kprobes: fix wait_for_kprobe_optimizer() | Date | Fri, 21 Dec 2012 17:57:00 -0800 |
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wait_for_kprobe_optimizer() seems largely broken. It uses optimizer_comp which is never re-initialized, so wait_for_kprobe_optimizer() will never wait for anything once kprobe_optimizer() finishes all pending jobs for the first time.
Also, aside from completion, delayed_work_pending() is %false once kprobe_optimizer() starts execution and wait_for_kprobe_optimizer() won't wait for it.
Reimplement it so that it flushes optimizing_work until [un]optimizing_lists are empty. Note that this also makes optimizing_work execute immediately if someone's waiting for it, which is the nicer behavior.
Only compile tested.
Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Cc: "David S. Miller" <davem@davemloft.net> Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> --- Please let me know how this patch should be routed. I can take it through the workqueue tree if necessary.
Thanks.
kernel/kprobes.c | 23 +++++++++++++++-------- 1 file changed, 15 insertions(+), 8 deletions(-)
diff --git a/kernel/kprobes.c b/kernel/kprobes.c index 098f396..f230e81 100644 --- a/kernel/kprobes.c +++ b/kernel/kprobes.c @@ -471,7 +471,6 @@ static LIST_HEAD(unoptimizing_list); static void kprobe_optimizer(struct work_struct *work); static DECLARE_DELAYED_WORK(optimizing_work, kprobe_optimizer); -static DECLARE_COMPLETION(optimizer_comp); #define OPTIMIZE_DELAY 5 /* @@ -552,8 +551,7 @@ static __kprobes void do_free_cleaned_kprobes(struct list_head *free_list) /* Start optimizer after OPTIMIZE_DELAY passed */ static __kprobes void kick_kprobe_optimizer(void) { - if (!delayed_work_pending(&optimizing_work)) - schedule_delayed_work(&optimizing_work, OPTIMIZE_DELAY); + schedule_delayed_work(&optimizing_work, OPTIMIZE_DELAY); } /* Kprobe jump optimizer */ @@ -592,16 +590,25 @@ static __kprobes void kprobe_optimizer(struct work_struct *work) /* Step 5: Kick optimizer again if needed */ if (!list_empty(&optimizing_list) || !list_empty(&unoptimizing_list)) kick_kprobe_optimizer(); - else - /* Wake up all waiters */ - complete_all(&optimizer_comp); } /* Wait for completing optimization and unoptimization */ static __kprobes void wait_for_kprobe_optimizer(void) { - if (delayed_work_pending(&optimizing_work)) - wait_for_completion(&optimizer_comp); + mutex_lock(&kprobe_mutex); + + while (!list_empty(&optimizing_list) || !list_empty(&unoptimizing_list)) { + mutex_unlock(&kprobe_mutex); + + /* this will also make optimizing_work execute immmediately */ + flush_delayed_work(&optimizing_work); + /* @optimizing_work might not have been queued yet, relax */ + cpu_relax(); + + mutex_lock(&kprobe_mutex); + } + + mutex_unlock(&kprobe_mutex); } /* Optimize kprobe if p is ready to be optimized */ -- 1.8.0.2
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