From owner-svn-src-all@FreeBSD.ORG Mon May 5 23:54:14 2014 Return-Path: Delivered-To: svn-src-all@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [8.8.178.115]) (using TLSv1 with cipher ADH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id 0DB71787; Mon, 5 May 2014 23:54:14 +0000 (UTC) Received: from svn.freebsd.org (svn.freebsd.org [IPv6:2001:1900:2254:2068::e6a:0]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id EF509315; Mon, 5 May 2014 23:54:13 +0000 (UTC) Received: from svn.freebsd.org ([127.0.1.70]) by svn.freebsd.org (8.14.8/8.14.8) with ESMTP id s45NsDPT043226; Mon, 5 May 2014 23:54:13 GMT (envelope-from neel@svn.freebsd.org) Received: (from neel@localhost) by svn.freebsd.org (8.14.8/8.14.8/Submit) id s45NsDOT043225; Mon, 5 May 2014 23:54:13 GMT (envelope-from neel@svn.freebsd.org) Message-Id: <201405052354.s45NsDOT043225@svn.freebsd.org> From: Neel Natu Date: Mon, 5 May 2014 23:54:13 +0000 (UTC) To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r265407 - head/usr.sbin/bhyve X-SVN-Group: head MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-BeenThere: svn-src-all@freebsd.org X-Mailman-Version: 2.1.18 Precedence: list List-Id: "SVN commit messages for the entire src tree \(except for " user" and " projects" \)" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 05 May 2014 23:54:14 -0000 Author: neel Date: Mon May 5 23:54:13 2014 New Revision: 265407 URL: http://svnweb.freebsd.org/changeset/base/265407 Log: Disable the 'uart_drain()' callback when the emulated receive FIFO is full. Failing to do this will cause the kevent(2) notification to trigger continuously and the bhyve(8) mevent thread will hog the cpu until the characters on the backend tty device are drained. Also, make the uart backend file descriptor non-blocking to avoid a select(2) before every byte read from that backend. Reviewed by: grehan Modified: head/usr.sbin/bhyve/uart_emul.c Modified: head/usr.sbin/bhyve/uart_emul.c ============================================================================== --- head/usr.sbin/bhyve/uart_emul.c Mon May 5 23:36:46 2014 (r265406) +++ head/usr.sbin/bhyve/uart_emul.c Mon May 5 23:54:13 2014 (r265407) @@ -110,6 +110,7 @@ struct uart_softc { uint8_t dlh; /* Baudrate divisor latch MSB */ struct fifo rxfifo; + struct mevent *mev; struct ttyfd tty; bool thre_int_pending; /* THRE interrupt pending */ @@ -145,34 +146,15 @@ ttyopen(struct ttyfd *tf) } } -static bool -tty_char_available(struct ttyfd *tf) -{ - fd_set rfds; - struct timeval tv; - - FD_ZERO(&rfds); - FD_SET(tf->fd, &rfds); - tv.tv_sec = 0; - tv.tv_usec = 0; - if (select(tf->fd + 1, &rfds, NULL, NULL, &tv) > 0 ) { - return (true); - } else { - return (false); - } -} - static int ttyread(struct ttyfd *tf) { - char rb; + unsigned char rb; - if (tty_char_available(tf)) { - read(tf->fd, &rb, 1); - return (rb & 0xff); - } else { + if (read(tf->fd, &rb, 1) == 1) + return (rb); + else return (-1); - } } static void @@ -183,62 +165,111 @@ ttywrite(struct ttyfd *tf, unsigned char } static void -fifo_reset(struct fifo *fifo, int size) +rxfifo_reset(struct uart_softc *sc, int size) { + char flushbuf[32]; + struct fifo *fifo; + ssize_t nread; + int error; + fifo = &sc->rxfifo; bzero(fifo, sizeof(struct fifo)); fifo->size = size; + + if (sc->tty.opened) { + /* + * Flush any unread input from the tty buffer. + */ + while (1) { + nread = read(sc->tty.fd, flushbuf, sizeof(flushbuf)); + if (nread != sizeof(flushbuf)) + break; + } + + /* + * Enable mevent to trigger when new characters are available + * on the tty fd. + */ + error = mevent_enable(sc->mev); + assert(error == 0); + } +} + +static int +rxfifo_available(struct uart_softc *sc) +{ + struct fifo *fifo; + + fifo = &sc->rxfifo; + return (fifo->num < fifo->size); } static int -fifo_putchar(struct fifo *fifo, uint8_t ch) +rxfifo_putchar(struct uart_softc *sc, uint8_t ch) { + struct fifo *fifo; + int error; + + fifo = &sc->rxfifo; if (fifo->num < fifo->size) { fifo->buf[fifo->windex] = ch; fifo->windex = (fifo->windex + 1) % fifo->size; fifo->num++; + if (!rxfifo_available(sc)) { + if (sc->tty.opened) { + /* + * Disable mevent callback if the FIFO is full. + */ + error = mevent_disable(sc->mev); + assert(error == 0); + } + } return (0); } else return (-1); } static int -fifo_getchar(struct fifo *fifo) +rxfifo_getchar(struct uart_softc *sc) { - int c; + struct fifo *fifo; + int c, error, wasfull; + wasfull = 0; + fifo = &sc->rxfifo; if (fifo->num > 0) { + if (!rxfifo_available(sc)) + wasfull = 1; c = fifo->buf[fifo->rindex]; fifo->rindex = (fifo->rindex + 1) % fifo->size; fifo->num--; + if (wasfull) { + if (sc->tty.opened) { + error = mevent_enable(sc->mev); + assert(error == 0); + } + } return (c); } else return (-1); } static int -fifo_numchars(struct fifo *fifo) +rxfifo_numchars(struct uart_softc *sc) { + struct fifo *fifo = &sc->rxfifo; return (fifo->num); } -static int -fifo_available(struct fifo *fifo) -{ - - return (fifo->num < fifo->size); -} - static void uart_opentty(struct uart_softc *sc) { - struct mevent *mev; ttyopen(&sc->tty); - mev = mevent_add(sc->tty.fd, EVF_READ, uart_drain, sc); - assert(mev); + sc->mev = mevent_add(sc->tty.fd, EVF_READ, uart_drain, sc); + assert(sc->mev != NULL); } /* @@ -255,7 +286,7 @@ uart_intr_reason(struct uart_softc *sc) if ((sc->lsr & LSR_OE) != 0 && (sc->ier & IER_ERLS) != 0) return (IIR_RLS); - else if (fifo_numchars(&sc->rxfifo) > 0 && (sc->ier & IER_ERXRDY) != 0) + else if (rxfifo_numchars(sc) > 0 && (sc->ier & IER_ERXRDY) != 0) return (IIR_RXTOUT); else if (sc->thre_int_pending && (sc->ier & IER_ETXRDY) != 0) return (IIR_TXRDY); @@ -274,7 +305,7 @@ uart_reset(struct uart_softc *sc) sc->dll = divisor; sc->dlh = divisor >> 16; - fifo_reset(&sc->rxfifo, 1); /* no fifo until enabled by software */ + rxfifo_reset(sc, 1); /* no fifo until enabled by software */ } /* @@ -315,9 +346,9 @@ uart_drain(int fd, enum ev_type ev, void if ((sc->mcr & MCR_LOOPBACK) != 0) { (void) ttyread(&sc->tty); } else { - while (fifo_available(&sc->rxfifo) && + while (rxfifo_available(sc) && ((ch = ttyread(&sc->tty)) != -1)) { - fifo_putchar(&sc->rxfifo, ch); + rxfifo_putchar(sc, ch); } uart_toggle_intr(sc); } @@ -351,7 +382,7 @@ uart_write(struct uart_softc *sc, int of switch (offset) { case REG_DATA: if (sc->mcr & MCR_LOOPBACK) { - if (fifo_putchar(&sc->rxfifo, value) != 0) + if (rxfifo_putchar(sc, value) != 0) sc->lsr |= LSR_OE; } else if (sc->tty.opened) { ttywrite(&sc->tty, value); @@ -372,7 +403,7 @@ uart_write(struct uart_softc *sc, int of */ if ((sc->fcr & FCR_ENABLE) ^ (value & FCR_ENABLE)) { fifosz = (value & FCR_ENABLE) ? FIFOSZ : 1; - fifo_reset(&sc->rxfifo, fifosz); + rxfifo_reset(sc, fifosz); } /* @@ -383,7 +414,7 @@ uart_write(struct uart_softc *sc, int of sc->fcr = 0; } else { if ((value & FCR_RCV_RST) != 0) - fifo_reset(&sc->rxfifo, FIFOSZ); + rxfifo_reset(sc, FIFOSZ); sc->fcr = value & (FCR_ENABLE | FCR_DMA | FCR_RX_MASK); @@ -480,7 +511,7 @@ uart_read(struct uart_softc *sc, int off switch (offset) { case REG_DATA: - reg = fifo_getchar(&sc->rxfifo); + reg = rxfifo_getchar(sc); break; case REG_IER: reg = sc->ier; @@ -511,7 +542,7 @@ uart_read(struct uart_softc *sc, int off sc->lsr |= LSR_TEMT | LSR_THRE; /* Check for new receive data */ - if (fifo_numchars(&sc->rxfifo) > 0) + if (rxfifo_numchars(sc) > 0) sc->lsr |= LSR_RXRDY; else sc->lsr &= ~LSR_RXRDY; @@ -615,6 +646,10 @@ uart_set_backend(struct uart_softc *sc, retval = 0; } + /* Make the backend file descriptor non-blocking */ + if (retval == 0) + retval = fcntl(sc->tty.fd, F_SETFL, O_NONBLOCK); + if (retval == 0) uart_opentty(sc);