Messages in this thread | | | Date | Wed, 21 Jun 2006 11:55:52 +1000 | From | Peter Williams <> | Subject | Re: [Lse-tech] [PATCH 09/11] Task watchers: Add support for per-task watchers |
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Andrew Morton wrote: > On Tue, 20 Jun 2006 18:20:48 -0700 > Matt Helsley <matthltc@us.ibm.com> wrote: > >>>>>> +static inline int notify_per_task_watchers(unsigned int val, >>>>>> + struct task_struct *task) >>>>>> +{ >>>>>> + if (get_watch_event(val) != WATCH_TASK_INIT) >>>>>> + return raw_notifier_call_chain(&task->notify, val, task); >>>>>> + RAW_INIT_NOTIFIER_HEAD(&task->notify); >>>>>> + if (task->real_parent) >>>>>> + return raw_notifier_call_chain(&task->real_parent->notify, >>>>>> + val, task); >>>>>> +} >>>>> It's possible for this task to exit without returning a result. >>>> Assuming you meant s/task/function/: >>>> >>>> In the common case this will return a result because most tasks have a >>>> real parent. The only exception should be the init task. However, the >>>> init task does not "fork" from another task so this function will never >>>> get called with WATCH_TASK_INIT and the init task. >>>> >>>> This means that if one wants to use per-task watchers to associate data >>>> and a function call with *every* task, special care will need to be >>>> taken to register with the init task. >>> no...... >> I've been looking through the source and, from what I can see, the end >> of the function is not reachable. I think I need to add: >> >> notify_watchers(WATCH_TASK_INIT, &init_task); >> >> to make this into an applicable warning. > > If the end of the function isn't reachable then the > `if (task->real_parent)' can simply be removed.
Perhaps with a comment to say that it's safe (and why) to dereference task->real_parent to help code reviewers?
Peter -- Peter Williams pwil3058@bigpond.net.au
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