----- Original Message ----- > From: "Jeff Darcy" <jdarcy@xxxxxxxxxx> > To: "Krishnan Parthasarathi" <kparthas@xxxxxxxxxx>, gluster-devel@xxxxxxxxxx > Sent: Monday, October 8, 2012 6:10:46 PM > Subject: Re: glusterd crashes when synctask is used in conjunction with inner functions. > > On October 8, 2012 7:02:34 AM Krishnan Parthasarathi > <kparthas@xxxxxxxxxx> wrote: > > I have been rewriting some of the volume operations (like > > volume-start, > > volume-add-brick, volume-remove-brick) using synctask library (aka > > syncops). > > This change has the following immediate benefits, > > > > - volume-start would return success/failure depending on the > > success/failure of > > brick process(es) spawned. > > - would make glusterd's epoll thread 'more' available. > > > > </context> > > > > While I was making the changes in http://review.gluster.com/3969, I > > noticed that > > whenever the code executing on a synctask called into dict_foreach, > > which was supplied > > a function ptr, defined as an inner function, glusterd crashed. > > When I rewrote > > inner function as a static function, glusterd wouldn't crash. > > > > Has anyone seen or can explain (or give possible leads to analyse) > > this > > behaviour? > > FWIW, inner functions are only available as part of GNU extensions > > to C. So, I > > assumed it is not such a bad thing to move the inner functions > > 'out', > > in my patch. > > Ugh. I noticed this pattern while I was looking at some AFR stuff > recently. I thought it was rather clever, and pondered a bit about > how > it might be implemented in gcc/libc. Apparently it was a bit too > clever, and the implementation leaves something to be desired. An > inner function might be more elegant than defining private structures > to pass through our own context pointer, but in the interest of both > portability and not having to debug compiler code I think changing > these to work the "old fashioned" way would actually be a good thing. FWIW, inner functions also make it harder to debug with gdb (read breakpoints). I am yet to demonstrably establish that inner functions' would crash when run in synctask. I hope some of you might be able to shed light on how I could resolve that. thanks, krish > > >
