Date: Thu, 23 Sep 2004 16:38:06 +0900 From: Pyun YongHyeon <yongari@kt-is.co.kr> To: dhaigh@gatorzone.com Cc: sparc64@FreeBSD.org Subject: Re: PR sparc64/71729 Message-ID: <20040923073806.GA12622@kt-is.co.kr> In-Reply-To: <20040922083625.GA8910@kt-is.co.kr> References: <!~!UENERkVCMDkAAQACAAAAAAAAAAAAAAAAABgAAAAAAAAACQvSeqVn1BGUQgBglOsMr8KAAAAQAAAAcPmXkBll7EW4XKEqja5UUQEAAAAA@nc.rr.com> <20040920104006.GA1905@kt-is.co.kr> <20040922083625.GA8910@kt-is.co.kr>
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--liOOAslEiF7prFVr Content-Type: text/plain; charset=us-ascii Content-Disposition: inline On Wed, Sep 22, 2004 at 05:36:25PM +0900, To dhaigh@gatorzone.com wrote: > On Mon, Sep 20, 2004 at 07:40:06PM +0900, To dhaigh@gatorzone.com wrote: > > On Fri, Sep 17, 2004 at 09:29:41AM -0400, Doug Haigh wrote: > > > > > > I am not sure if the PR got updated, but I wanted to let you know that the > > > printf in a kernel thread only fails if you are on a SMP machine. It appears > > > that if you printf on a CPU other than CPU #0, it will panic the kernel. > > > > > > > After reading your mail, I made a small test program which creates > > a kernel thread and ran it on AXe(UP) and U2(SMP). > > Under AXe it worked as expected but it paniced on U2. > > So it seems that there is some issues in OF console. > > Backtrace for the panic is somthing like: > > > > While looking into the ofw_console(4) code I noticed there is > possible races there. So I patched the code and ran it. However > it didn't fix the problem. Since we can't simply use a mutex in > ofw_cons_putc(), there should be other way to workaround this. > Have no idea yet. > Ok, here is patch for ofw_console(4). This patch should fix kernel panic when a kernel thread tries to write chars via ofw_console(4) interface. It seems that the patch works well on my U2/AXe. I'd like to know whether it works on other Ultrasprcs. Also it would be great if it doesn't produce negative impacts on PPC too. Cheers, Pyun YongHyeon -- Pyun YongHyeon <http://www.kr.freebsd.org/~yongari>; --liOOAslEiF7prFVr Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename="ofw_console.patch" --- sys/dev/ofw/ofw_console.c.orig Wed Aug 4 09:21:19 2004 +++ sys/dev/ofw/ofw_console.c Thu Sep 23 16:19:29 2004 @@ -47,6 +47,25 @@ #define OFWCONS_POLL_HZ 4 /* 50-100 works best on Ultra2 */ #endif #define OFBURSTLEN 128 /* max number of bytes to write in one chunk */ +#define OFWCONS_POLL 1 +#define PCHAR_MAX 128 + +struct ofw_softc { + struct cdev *ofw_dev; + struct tty *ofw_tty; + struct callout ofw_co; + int polltime; + u_int8_t pchar[PCHAR_MAX]; + int phead; + int ptail; + int ccnt; + int ofw_flags; + struct mtx lock; +}; +static struct ofw_softc ofw_sc; + +#define OFWCONS_LOCK(sc) mtx_lock_spin(&sc->lock) +#define OFWCONS_UNLOCK(sc) mtx_unlock_spin(&sc->lock) static d_open_t ofw_dev_open; static d_close_t ofw_dev_close; @@ -59,11 +78,6 @@ .d_flags = D_TTY | D_NEEDGIANT, }; -static struct tty *ofw_tp = NULL; -static int polltime; -static struct callout_handle ofw_timeouthandle - = CALLOUT_HANDLE_INITIALIZER(&ofw_timeouthandle); - #if defined(KDB) && defined(ALT_BREAK_TO_DEBUGGER) static int alt_break_state; #endif @@ -71,7 +85,7 @@ static void ofw_tty_start(struct tty *); static int ofw_tty_param(struct tty *, struct termios *); static void ofw_tty_stop(struct tty *, int); -static void ofw_timeout(void *); +static void ofw_pollc(void *); static cn_probe_t ofw_cons_probe; static cn_init_t ofw_cons_init; @@ -87,7 +101,8 @@ { phandle_t options; char output[32]; - struct cdev *dev; + struct ofw_softc *sc; + struct tty *tp; if (ofw_consdev.cn_pri != CN_DEAD && ofw_consdev.cn_name[0] != '\0') { @@ -95,9 +110,22 @@ OF_getprop(options, "output-device", output, sizeof(output)) == -1) return; - dev = make_dev(&ofw_cdevsw, 0, UID_ROOT, GID_WHEEL, 0600, "%s", - output); - make_dev_alias(dev, "ofwcons"); + sc = &ofw_sc; + bzero(sc, sizeof(*sc)); + mtx_init(&sc->lock, "ofw_cons mtx", NULL, MTX_SPIN); + sc->ofw_dev = make_dev(&ofw_cdevsw, 0, UID_ROOT, GID_WHEEL, + 0600, "%s", output); + make_dev_alias(sc->ofw_dev, "ofwcons"); + tp = ttymalloc(NULL); + tp->t_sc = sc; + sc->ofw_dev->si_drv1 = sc; + sc->ofw_dev->si_tty = tp; + sc->ofw_tty = tp; + tp->t_dev = sc->ofw_dev; + tp->t_oproc = ofw_tty_start; + tp->t_param = ofw_tty_param; + tp->t_stop = ofw_tty_stop; + callout_init(&sc->ofw_co, 0); } } @@ -109,20 +137,13 @@ static int ofw_dev_open(struct cdev *dev, int flag, int mode, struct thread *td) { + struct ofw_softc *sc; struct tty *tp; - int unit; - int error, setuptimeout; + int error; + sc = dev->si_drv1; + tp = dev->si_tty; error = 0; - setuptimeout = 0; - unit = minor(dev); - - tp = ofw_tp = dev->si_tty = ttymalloc(ofw_tp); - - tp->t_oproc = ofw_tty_start; - tp->t_param = ofw_tty_param; - tp->t_stop = ofw_tty_stop; - tp->t_dev = dev; if ((tp->t_state & TS_ISOPEN) == 0) { tp->t_state |= TS_CARR_ON; @@ -133,21 +154,20 @@ tp->t_lflag = TTYDEF_LFLAG; tp->t_ispeed = tp->t_ospeed = TTYDEF_SPEED; ttsetwater(tp); - - setuptimeout = 1; } else if ((tp->t_state & TS_XCLUDE) && suser(td)) { return (EBUSY); } + if ((error = tty_open(dev, tp))) + return (error); error = ttyld_open(tp, dev); - - if (error == 0 && setuptimeout) { - polltime = hz / OFWCONS_POLL_HZ; - if (polltime < 1) { - polltime = 1; - } - - ofw_timeouthandle = timeout(ofw_timeout, tp, polltime); + if (error == 0 && (sc->ofw_flags & OFWCONS_POLL) == 0) { + sc->polltime = hz / OFWCONS_POLL_HZ; + if (sc->polltime < 1) + sc->polltime = 1; + sc->ofw_flags |= OFWCONS_POLL; + callout_reset(&sc->ofw_co, sc->polltime, + ofw_pollc, tp); } return (error); @@ -156,18 +176,17 @@ static int ofw_dev_close(struct cdev *dev, int flag, int mode, struct thread *td) { - int unit; + struct ofw_softc *sc; struct tty *tp; - unit = minor(dev); - tp = ofw_tp; + sc = dev->si_drv1; + tp = dev->si_tty; - if (unit != 0) { - return (ENXIO); - } + if ((tp->t_state & TS_ISOPEN) == 0) + return (0); - /* XXX Should be replaced with callout_stop(9) */ - untimeout(ofw_timeout, tp, ofw_timeouthandle); + callout_stop(&sc->ofw_co); + sc->ofw_flags &= ~OFWCONS_POLL; ttyld_close(tp, flag); tty_close(tp); @@ -190,15 +209,18 @@ u_char buf[OFBURSTLEN]; - if (tp->t_state & (TS_TIMEOUT | TS_BUSY | TS_TTSTOP)) + if (tp->t_state & (TS_TIMEOUT | TS_BUSY | TS_TTSTOP)) { + ttwwakeup(tp); return; + } tp->t_state |= TS_BUSY; cl = &tp->t_outq; - len = q_to_b(cl, buf, OFBURSTLEN); - OF_write(stdout, buf, len); + while (cl->c_cc) { + len = q_to_b(cl, buf, OFBURSTLEN); + OF_write(stdout, buf, len); + } tp->t_state &= ~TS_BUSY; - ttwwakeup(tp); } @@ -214,20 +236,58 @@ } static void -ofw_timeout(void *v) +ofw_pollc(void *arg) { - struct tty *tp; - int c; + struct ofw_softc *sc; + struct tty *tp; + int l; + char ch; - tp = (struct tty *)v; + tp = (struct tty *)arg; + sc = tp->t_sc; - while ((c = ofw_cons_checkc(NULL)) != -1) { + OFWCONS_LOCK(sc); +#if 0 + for (; sc->ccnt > 0; sc->ccnt--) { + ch = sc->pchar[sc->phead]; + OF_write(stdout, &ch, 1); + if (++sc->phead >= PCHAR_MAX) + sc->phead = 0; + } +#else + /* + * Since interrupts are disabled during acqusition of MTX_SPIN lock, + * the following code fragments should be optmized and short enough + * in order not to monopolize other system resouces. + */ + if (sc->ccnt > 0) { + if (sc->phead + sc->ccnt <= PCHAR_MAX) { + OF_write(stdout, &sc->pchar[sc->phead], sc->ccnt); + sc->phead += sc->ccnt; + if (sc->phead >= PCHAR_MAX) + sc->phead = 0; + sc->ccnt = 0; + } else { + l = PCHAR_MAX - sc->phead; + OF_write(stdout, &sc->pchar[sc->phead], l); + sc->phead = 0; + sc->ccnt -= l; + if (sc->ccnt) { + OF_write(stdout, &sc->pchar[sc->phead], + sc->ccnt); + sc->phead += sc->ccnt; + sc->ccnt = 0; + } + } + } +#endif + OFWCONS_UNLOCK(sc); + while(OF_read(stdin, &ch, 1) > 0) { if (tp->t_state & TS_ISOPEN) { - ttyld_rint(tp, c); + ttyld_rint(tp, ch); } } - - ofw_timeouthandle = timeout(ofw_timeout, tp, polltime); + callout_reset(&sc->ofw_co, sc->polltime, ofw_pollc, tp); } static void @@ -256,10 +316,12 @@ static void ofw_cons_init(struct consdev *cp) { + struct ofw_softc *sc; /* XXX: This is the alias, but that should be good enough */ sprintf(cp->cn_name, "ofwcons"); - cp->cn_tp = ofw_tp; + sc = &ofw_sc; + cp->cn_tp = sc->ofw_tty; } static int @@ -269,7 +331,6 @@ int l; ch = '\0'; - while ((l = OF_read(stdin, &ch, 1)) != 1) { if (l != -2 && l != 0) { return (-1); @@ -303,13 +364,20 @@ static void ofw_cons_putc(struct consdev *cp, int c) { + struct ofw_softc *sc; char cbuf; - if (c == '\n') { - cbuf = '\r'; - OF_write(stdout, &cbuf, 1); - } - + sc = &ofw_sc; cbuf = c; - OF_write(stdout, &cbuf, 1); + if (sc->ofw_tty != NULL) { + /* not safe to write yet, queue it */ + OFWCONS_LOCK(sc); + sc->pchar[sc->ptail] = cbuf; + if (++sc->ptail >= PCHAR_MAX) + sc->ptail = 0; + if (++sc->ccnt >= PCHAR_MAX) + sc->ccnt = 0; + OFWCONS_UNLOCK(sc); + } else + OF_write(stdout, &cbuf, 1); } --liOOAslEiF7prFVr--
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