Linux-Kernel Archive: fsync() on unix domain sockets? fsync() on unix domain sockets? From: Dan Kegel (dank@kegel.com) Date: Tue Apr 08 2003 - 17:31:19 EST Next message: Andries.Brouwer@cwi.nl: "ioctls" Previous message: Martin Schlemmer: "Re: [PATCH-2.5] Fix w83781d sensor to use Milli-Volt for in_* in sysfs" Next in thread: Richard B. Johnson: "Re: fsync() on unix domain sockets?" Reply: Richard B. Johnson: "Re: fsync() on unix domain sockets?" Messages sorted by: [ date ] [ thread ] [ subject ] [ author ] Let's say someone had written a win32 emulator that ran in userspace, and was using unix domain sockets to emulate win32 named pipes. (Yes, this is how Wine does it at the moment, but it's a poor fit, and they're thinking of switching to emulating them 100% in userspace so they can get the semantics right.) It turns out that in this situation, it would be handy for fsync() to work on unix domain sockets. This would require a bit of plumbing to let sockets expose an fsync() method, together with an fsync() method for unix domain sockets. After thinking about this a bit, I couldn't resist writing that method for stream sockets. Being a kernel newbie, I am unsure if I got the locking and reference counting right. Anyone care to peek at it and see if there are glaring problems? (If not, I guess I could go do the needed plumbing and see how it works in practice.) Thanks, Dan /* to be added to net/unix/af_unix.c */ static long unix_stream_fsync(unix_socket * sk) { int err; long timeo; unix_socket *other; DECLARE_WAITQUEUE(wait, current); timeo = sock_sndtimeo(sk, 0); err = -ENOTCONN; other = unix_peer_get(sk); if (!other) goto out; unix_state_rlock(sk); add_wait_queue(sk->sleep, &wait); unix_state_runlock(sk); for (;;) { int breakme; unix_state_rlock(other); breakme = !skb_queue_len(&other->receive_queue) || other->err || (other->shutdown & RCV_SHUTDOWN) || !timeo; unix_state_runlock(other); if (breakme) break; if (signal_pending(current)) goto out_sig; set_current_state(TASK_INTERRUPTIBLE); timeo = schedule_timeout(timeo); } err = 0; out_run: __set_current_state(TASK_RUNNING); unix_state_rlock(sk); remove_wait_queue(sk->sleep, &wait); unix_state_runlock(sk); sock_put(other); out: return err; out_sig: err = sock_intr_errno(timeo); goto out_run; }
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Dan Kegel
http://www.kegel.com
http://counter.li.org/cgi-bin/runscript/display-person.cgi?user=78045
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Next message: Andries.Brouwer@cwi.nl: "ioctls" Previous message: Martin Schlemmer: "Re: [PATCH-2.5] Fix w83781d sensor to use Milli-Volt for in_* in sysfs" Next in thread: Richard B. Johnson: "Re: fsync() on unix domain sockets?" Reply: Richard B. Johnson: "Re: fsync() on unix domain sockets?" Messages sorted by: [ date ] [ thread ] [ subject ] [ author ] This archive was generated by hypermail 2b29 : Tue Apr 15 2003 - 22:00:16 EST
