On Fri, 4 Aug 2017 00:44:45, Noah Misch wrote: > --UugvWAfsgieZRqgk > Content-Type: text/plain; charset=us-ascii > Content-Disposition: inline > > The attached demonstration program blocks signals (with sigprocmask()) to > achieve mutual exclusion between signal handlers. It aborts upon receipt of a > blocked signal. On "CYGWIN_NT-10.0 2.7.0(0.306/5/3) 2017-02-12 13:18 x86_64", > signals regularly arrive despite being blocked. Essential parts of the > program include handling two signal numbers and having handlers run for at > least 1-2ms; this problem goes away if I remove one of those attributes. > GNU/Linux, AIX, Solaris, and "CYGWIN_NT-6.0 1.7.27(0.271/5/3) 2013-12-09 11:57 > i686" never deliver a blocked signal to this program. I think this Cygwin > behavior is non-conforming.
Hi Noah, I do not think that Cygwin is the problem here; your code is the problem here, I believe. Please, study, for example, chapters 20 and 21 of LPI (Linux Programming Interface by Michael Kerrisk). (20.10 The Signal Mask (Blocking Signal Delivery) (20.13 Changing Signal Dispositions: sigaction()) You cannot use sigprocmask() like you do; you cannot use SIG_SETMASK as a parameter in sigprocmask() within the context of a handler. Cygwin exhibits misbehaviour in case of your code, because it is slower than Linux; however, the code is also wrong for Linux. The misbehaviour occurs as result of nested interrupts in case of your code (yes, nested interrupts are possible with Linux/Unix!). However your code does not experience nesting under Linux, because, as I said, Linux is faster than Cygwin. ----- The simplest way to exclude one signal from another, is to specify the signal (or signals) in the sa_mask of the sigaction parameter ... see sigaction() ----- However if you desire 'control' during the execution of a handler, you have to resort to sigprocmask(), and use SIG_BLOCK and SIG_UNBLOCK, in order to add and remove a specific signal to/from the mask. see sigprocmask() You cannot use SIG_SETMASK in that context. Regards, Henri ===== -- Problem reports: http://cygwin.com/problems.html FAQ: http://cygwin.com/faq/ Documentation: http://cygwin.com/docs.html Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple