On Sun, Oct 29, 2017 at 08:15:46AM +0800, Yubin Ruan wrote:
> 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>
Applied, thank you!
Thanx, Paul
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