Date: Mon, 15 Aug 2016 14:28:17 +0000 (UTC) From: Bruce Evans <bde@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r304161 - head/sys/dev/syscons Message-ID: <201608151428.u7FESH7F084304@repo.freebsd.org>
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Author: bde Date: Mon Aug 15 14:28:16 2016 New Revision: 304161 URL: https://svnweb.freebsd.org/changeset/base/304161 Log: Change all uses of 'debugger' to kdb_active and remove this variable. This restores avoidance of doing dangerous things like calling wakeup() and callouts while in ddb. Initialization of 'debugger' was broken by removing the cndbctl() console method that was used mainly in this driver to initialize 'debugger' and switch to the console screen on entry to ddb. The screen switch was restored using the cngrab() method, but cngrab() is more general so it should not initialize 'debugger' and never did. 'debugger' was just an over-engineered alias for kdb_active anyway. It existed because kdb_active (when it was named ddb_active) was considered as a private kdb variable, and there are ordering problems initializing the variables atomically with the state that they represent, but an extra variable and method to set it increased these problems. The bug caused LORs, but WITNESS is normally misconfigured with WITNESS_SKIPSIN so it doesn't check the spinlocks used by wakeup() and callouts. Modified: head/sys/dev/syscons/syscons.c Modified: head/sys/dev/syscons/syscons.c ============================================================================== --- head/sys/dev/syscons/syscons.c Mon Aug 15 14:28:08 2016 (r304160) +++ head/sys/dev/syscons/syscons.c Mon Aug 15 14:28:16 2016 (r304161) @@ -172,8 +172,6 @@ SYSCTL_INT(_machdep, OID_AUTO, enable_pa #define VTY_WCHAN(sc, vty) (&SC_DEV(sc, vty)) -static int debugger; - /* prototypes */ static int sc_allocate_keyboard(sc_softc_t *sc, int unit); static int scvidprobe(int unit, int flags, int cons); @@ -1815,7 +1813,7 @@ sccnupdate(scr_stat *scp) if (suspend_in_progress || scp->sc->font_loading_in_progress) return; - if (debugger > 0 || panicstr || shutdown_in_progress) { + if (kdb_active || panicstr || shutdown_in_progress) { sc_touch_scrn_saver(); } else if (scp != scp->sc->cur_scp) { return; @@ -1884,7 +1882,7 @@ scrn_timer(void *arg) #endif /* PC98 */ /* should we stop the screen saver? */ - if (debugger > 0 || panicstr || shutdown_in_progress) + if (kdb_active || panicstr || shutdown_in_progress) sc_touch_scrn_saver(); if (run_scrn_saver) { if (time_uptime > sc->scrn_time_stamp + scrn_blank_time) @@ -2279,7 +2277,7 @@ stop_scrn_saver(sc_softc_t *sc, void (*s mark_all(sc->cur_scp); if (sc->delayed_next_scr) sc_switch_scr(sc, sc->delayed_next_scr - 1); - if (debugger == 0) + if (!kdb_active) wakeup(&scrn_blanked); } @@ -2474,7 +2472,7 @@ sc_switch_scr(sc_softc_t *sc, u_int next DPRINTF(5, ("error 2, requested vty isn't open!\n")); return EINVAL; } - if ((debugger > 0) && (SC_STAT(tp)->smode.mode == VT_PROCESS)) { + if (kdb_active && SC_STAT(tp)->smode.mode == VT_PROCESS) { splx(s); DPRINTF(5, ("error 3, requested vty is in the VT_PROCESS mode\n")); return EINVAL; @@ -2495,7 +2493,7 @@ sc_switch_scr(sc_softc_t *sc, u_int next * is supposed to be locked by splhigh(), but the debugger may * be invoked at splhigh(). */ - if (debugger == 0) + if (!kdb_active) wakeup(VTY_WCHAN(sc,next_scr)); splx(s); DPRINTF(5, ("switch done (new == old)\n")); @@ -2518,7 +2516,7 @@ sc_switch_scr(sc_softc_t *sc, u_int next s = spltty(); /* wake up processes waiting for this vty */ - if (debugger == 0) + if (!kdb_active) wakeup(VTY_WCHAN(sc,next_scr)); /* wait for the controlling process to acknowledge, if necessary */
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