From owner-freebsd-hackers@FreeBSD.ORG Wed Feb 6 04:41:42 2013 Return-Path: Delivered-To: freebsd-hackers@FreeBSD.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by hub.freebsd.org (Postfix) with ESMTP id 5FB814E2 for ; Wed, 6 Feb 2013 04:41:42 +0000 (UTC) (envelope-from ian@FreeBSD.org) Received: from duck.symmetricom.us (duck.symmetricom.us [206.168.13.214]) by mx1.freebsd.org (Postfix) with ESMTP id 3FA46C0F for ; Wed, 6 Feb 2013 04:41:41 +0000 (UTC) Received: from damnhippie.dyndns.org (daffy.symmetricom.us [206.168.13.218]) by duck.symmetricom.us (8.14.6/8.14.6) with ESMTP id r164ffFR003702 for ; Tue, 5 Feb 2013 21:41:41 -0700 (MST) (envelope-from ian@FreeBSD.org) Received: from [172.22.42.240] (revolution.hippie.lan [172.22.42.240]) by damnhippie.dyndns.org (8.14.3/8.14.3) with ESMTP id r164fcRL032480 for ; Tue, 5 Feb 2013 21:41:38 -0700 (MST) (envelope-from ian@FreeBSD.org) Subject: Request for review, time_pps_fetch() enhancement From: Ian Lepore To: "freebsd-hackers@freebsd.org" Content-Type: multipart/mixed; boundary="=-6J1XeQ0MmbsUd9NHPIee" Date: Tue, 05 Feb 2013 21:41:38 -0700 Message-ID: <1360125698.93359.566.camel@revolution.hippie.lan> Mime-Version: 1.0 X-Mailer: Evolution 2.32.1 FreeBSD GNOME Team Port X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 06 Feb 2013 04:41:42 -0000 --=-6J1XeQ0MmbsUd9NHPIee Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit I'd like feedback on the attached patch, which adds support to our time_pps_fetch() implementation for the blocking behaviors described in section 3.4.3 of RFC 2783. The existing implementation can only return the most recently captured data without blocking. These changes add the ability to block (forever or with timeout) until a new event occurs. -- Ian --=-6J1XeQ0MmbsUd9NHPIee Content-Disposition: inline; filename="pps_fetchwait.diff" Content-Type: text/x-patch; name="pps_fetchwait.diff"; charset="us-ascii" Content-Transfer-Encoding: 7bit Index: sys/kern/kern_tc.c =================================================================== --- sys/kern/kern_tc.c (revision 246337) +++ sys/kern/kern_tc.c (working copy) @@ -1446,6 +1446,50 @@ * RFC 2783 PPS-API implementation. */ +static int +pps_fetch(struct pps_fetch_args *fapi, struct pps_state *pps) +{ + int err, timo; + pps_seq_t aseq, cseq; + struct timeval tv; + + if (fapi->tsformat && fapi->tsformat != PPS_TSFMT_TSPEC) + return (EINVAL); + + /* + * If no timeout is requested, immediately return whatever values were + * most recently captured. If timeout seconds is -1, that's a request + * to block without a timeout. WITNESS won't let us sleep forever + * without a lock (we really don't need a lock), so just repeatedly + * sleep a long time. + */ + if (fapi->timeout.tv_sec || fapi->timeout.tv_nsec) { + if (fapi->timeout.tv_sec == -1) + timo = 0x7fffffff; + else { + tv.tv_sec = fapi->timeout.tv_sec; + tv.tv_usec = fapi->timeout.tv_nsec / 1000; + timo = tvtohz(&tv); + } + aseq = pps->ppsinfo.assert_sequence; + cseq = pps->ppsinfo.clear_sequence; + while (aseq == pps->ppsinfo.assert_sequence && + cseq == pps->ppsinfo.clear_sequence) { + err = tsleep(pps, PCATCH, "ppsfch", timo); + if (err == EWOULDBLOCK && fapi->timeout.tv_sec == -1) { + continue; + } else if (err != 0) { + return (err); + } + } + } + + pps->ppsinfo.current_mode = pps->ppsparam.mode; + fapi->pps_info_buf = pps->ppsinfo; + + return (0); +} + int pps_ioctl(u_long cmd, caddr_t data, struct pps_state *pps) { @@ -1485,13 +1529,7 @@ return (0); case PPS_IOC_FETCH: fapi = (struct pps_fetch_args *)data; - if (fapi->tsformat && fapi->tsformat != PPS_TSFMT_TSPEC) - return (EINVAL); - if (fapi->timeout.tv_sec || fapi->timeout.tv_nsec) - return (EOPNOTSUPP); - pps->ppsinfo.current_mode = pps->ppsparam.mode; - fapi->pps_info_buf = pps->ppsinfo; - return (0); + return (pps_fetch(fapi, pps)); #ifdef FFCLOCK case PPS_IOC_FETCH_FFCOUNTER: fapi_ffc = (struct pps_fetch_ffc_args *)data; @@ -1540,7 +1578,7 @@ void pps_init(struct pps_state *pps) { - pps->ppscap |= PPS_TSFMT_TSPEC; + pps->ppscap |= PPS_TSFMT_TSPEC | PPS_CANWAIT; if (pps->ppscap & PPS_CAPTUREASSERT) pps->ppscap |= PPS_OFFSETASSERT; if (pps->ppscap & PPS_CAPTURECLEAR) @@ -1680,6 +1718,9 @@ hardpps(tsp, ts.tv_nsec + 1000000000 * ts.tv_sec); } #endif + + /* Wakeup anyone sleeping in pps_fetch(). */ + wakeup(pps); } /* --=-6J1XeQ0MmbsUd9NHPIee--