On Tue, Apr 03, 2018 at 02:20:43PM +0100, Chris Wilson wrote: > Quoting Matthew Wilcox (2018-04-03 14:10:25) > > On Tue, Apr 03, 2018 at 01:33:15PM +0100, Chris Wilson wrote: > > > Quoting Matthew Wilcox (2018-04-02 15:10:58) > > > > I don't think the graphics drivers really want to be interrupted by > > > > any signal. > > > > > > Assume the worst case and we may block for 10s. Even a 10ms delay may be > > > unacceptable to some signal handlers (one presumes). For the number one > > > ^C usecase, yes that may be reduced to only bother if it's killable, but > > > I wonder if there are not timing loops (e.g. sigitimer in Xorg < 1.19) > > > that want to be able to interrupt random blockages. > > > > Ah, setitimer / SIGALRM. So what do we want to have happen if that > > signal handler touches the mmaped device memory? > > Burn in a great ball of fire :) Isn't that what usually happens if you > do anything in a signal handler? I don't know. My mummy and daddy don't let me play with sharp things like signals. > Hmm, if SIGBUS has a handler does that count as a killable signal? The > ddx does have code to service SIGBUS emitted when accessing the mmapped > pointer that may result from the page insertion failing with no memory > (or other random error). There we stop accessing via the pointer and > use another indirect method. Any signal with a handler is non-fatal, and so a call to mutex_lock_killable() would not return if SIGBUS was delivered to a thread blocking in a page fault. mutex_lock_interruptible() would return -EINTR.
