Date: Wed, 16 May 2012 21:28:37 +0400 From: Dmitry Marakasov <amdmi3@amdmi3.ru> To: bug-followup@FreeBSD.org Cc: multimedia@FreeBSD.org Subject: Re: ports/167971: [PATCH] audio/jack: ALSA driver is broken Message-ID: <20120516172837.GD15922@hades.panopticon> In-Reply-To: <20120516160955.1668170D@hades.panopticon> References: <20120516160955.1668170D@hades.panopticon>
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* Dmitry Marakasov (amdmi3@amdmi3.ru) wrote: > Since the second argument of clock_nanosleep (flags) is 0, ts still specifies a relative time, so theoretically the call may be replaced with simple nanosleep(&ts, NULL). I'm, however, unaware of differences between CLOCK_MONOTONIC and other clock types, as well as which of them is used by FreeBSD's nanosleep(), so it may have implications. NB: the same fix is used in multimedia/gavl file:///usr/ports/multimedia/gavl/files/patch-gavl-time.c and, judging from Linux man it should be safe: http://linux.die.net/man/2/nanosleep: --- POSIX.1 specifies that nanosleep() should measure time against the CLOCK_REALTIME clock. However, Linux measures the time using the CLOCK_MONOTONIC clock. This probably does not matter, since the POSIX.1 specification for clock_settime(2) says that discontinuous changes in CLOCK_REALTIME should not affect nanosleep() --- Thus, if FreeBSD nanosleep conforms to POSIX.1, it shouldn't matter for FreeBSD as well, so clock_nanosleep(CLOCK_MONOTONIC, 0, ...) -> nanosleep(...) replacement is safe. Thus, the PR is fixed by this patch (http://people.freebsd.org/~amdmi3/patch-drivers-alsa-midi-alsa_rawmidi.c): --- ./drivers/alsa-midi/alsa_rawmidi.c.orig 2008-05-29 16:26:07.000000000 +0400 +++ ./drivers/alsa-midi/alsa_rawmidi.c 2012-05-16 20:10:24.645166068 +0400 @@ -853,7 +853,7 @@ struct timespec ts; ts.tv_sec = 0; ts.tv_nsec = wait_nanosleep; - clock_nanosleep(CLOCK_MONOTONIC, 0, &ts, NULL); + nanosleep(&ts, NULL); } int res = poll((struct pollfd*)&pfds, npfds, poll_timeout); //debug_log("midi_thread(%s): poll exit: %d", str->name, res); -- Dmitry Marakasov . 55B5 0596 FF1E 8D84 5F56 9510 D35A 80DD F9D2 F77D amdmi3@amdmi3.ru ..: jabber: amdmi3@jabber.ru http://www.amdmi3.ru
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