From mboxrd@z Thu Jan 1 00:00:00 1970 From: lm@mcvoy.com (Larry McVoy) Date: Fri, 1 Dec 2017 08:18:10 -0800 Subject: [TUHS] signals and blocked in I/O In-Reply-To: References: <20171201154448.GL3924@mcvoy.com> Message-ID: <20171201161810.GM3924@mcvoy.com> On Fri, Dec 01, 2017 at 11:11:56AM -0500, Clem Cole wrote: > It's hard because if I/O (like DMA) is in progress, what are the proper > semantics to exit/roll back? When do you stop the transfer and what > happens. When doing direct to/from disk (like a in a real-time system), > this can get tricky. So at first blush, what it seems like is you need a barrier to starting more DMA's. You take the signal, the signal changes state to say to the I/O system "finish what you are doing but then no more". Or what you do is kill the process, tear down all of the pages except those that are locked for I/O, leave those in the process and wait for the I/O to get done. That might be simpler.