On 10/28/2017 09:17 PM, Paul E. McKenney wrote:
> On Sat, Oct 28, 2017 at 09:37:20PM +0800, Yubin Ruan wrote:
>> On Fri, Oct 27, 2017 at 04:24:08PM -0700, Paul E. McKenney wrote:
>>> On Sat, Oct 28, 2017 at 12:18:47AM +0900, Akira Yokosawa wrote:
>>>> On 2017/10/27 18:33, Yubin Ruan wrote:
>>>>> And here are some more modification to some wording in chapter 7, but I am not
>>>>> sure whether you like it or not.
>>>>>
>>>>> Anyway, chapter 7 makes me feel good ;-) It makes me know that home-brewing a
>>>>> lock primitives with atomic instructions(which is what I was doing) is
>>>>> something that is possible and used in production.
>>>>>
>>>>> Thanks,
>>>>> Yubin
>>>>>
>>>>> diff --git a/locking/locking.tex b/locking/locking.tex
>>>>> index 14db27d..a9f46f1 100644
>>>>> --- a/locking/locking.tex
>>>>> +++ b/locking/locking.tex
>>>>> @@ -2166,8 +2166,8 @@ Signal-handler deadlocks can be explicitly avoided as follows:
>>>>> of a signal handler.
>>>>> \item If the application invokes the library function
>>>>> while holding a lock acquired within a given signal
>>>>> - handler, then that signal must be blocked every time that the
>>>>> - library function is called outside of a signal handler.
>>>>> + handler, then that signal must be blocked every time that lock
>>>>> + is to be acquired outside of a signal handler.
>>>>
>>>> The talking point here is library function and signal handler. So something like:
>>>>
>>>> + handler, then that signal must be blocked every time that one
>>>> + of related library functions is called outside of the signal handler.
>>>>
>>>> Thoughts?
>>>
>>> I believe that the major problem is that I didn't really specify the
>>> situation and constraints. How about the following?
>>>
>>> Thanx, Paul
>>>
>>> -----------------------------------------------------------------------
>>>
>>> commit 85025eaceff8cf10c9b674ba70d33dbd012e27ce
>>> Author: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
>>> Date: Fri Oct 27 16:21:33 2017 -0700
>>>
>>> locking: Clarify explicit avoidance of signal-handler deadlocks
>>>
>>> Reported-by: Yubin Ruan <ablacktshirt@xxxxxxxxx>
>>> Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
>>>
>>> diff --git a/locking/locking.tex b/locking/locking.tex
>>> index 14db27d1148b..025320b294ed 100644
>>> --- a/locking/locking.tex
>>> +++ b/locking/locking.tex
>>> @@ -2157,7 +2157,17 @@ locks, the strategies in the next section may prove helpful.
>>> \subsubsection{Explicitly Avoid Signal-Handler Deadlocks}
>>> \label{sec:locking:Explicitly Avoid Signal-Handler Deadlocks}
>>>
>>> -Signal-handler deadlocks can be explicitly avoided as follows:
>>> +Suppose that a given library function is known to acquire locks,
>>> +but does not block signals.
>>> +Suppose further that it is necessary to invoke that function both from
>>> +within and outside of a signal handler, and that it is not permissible
>>> +to modify this library function.
>>> +Of course, if no special action is taken, then if a signal arrives
>>> +while that library function is holding its lock, deadlock can occur
>>> +when the signal handler invokes that same library function,
>>> +which in turn attempts to re-acquire that same lock.
>>> +
>>> +Such deadlocks can be avoided as follows:
>>>
>>> \begin{enumerate}
>>> \item If the application invokes the library function from
>>
>> These all look good to me. Thank you Paul.
>
> Very good, I will push it out. May I have your Acked-by?
> (As in "Acked-by: Yubin Ruan <ablacktshirt@xxxxxxxxx>".)
>
> (If I don't hear otherwise in about 12 hours, I will just push it
> out as is.)
Acked-by: Yubin Ruan <ablacktshirt@xxxxxxxxx>
Yubin
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