Date: Tue, 19 Jan 2016 18:45:27 -0800 From: John Baldwin <jhb@freebsd.org> To: Marius Strobl <marius@freebsd.org> Cc: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: Re: svn commit: r294362 - in head/sys: dev/uart kern sys Message-ID: <29108223.BFrmB7fo1m@ralph.baldwin.cx> In-Reply-To: <1839427.BLR7n8zvy2@ralph.baldwin.cx> References: <201601192334.u0JNYST5080954@repo.freebsd.org> <2881455.20ba4MY9ds@ralph.baldwin.cx> <1839427.BLR7n8zvy2@ralph.baldwin.cx>
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On Tuesday, January 19, 2016 06:36:04 PM John Baldwin wrote: > On Tuesday, January 19, 2016 06:14:14 PM John Baldwin wrote: > > On Tuesday, January 19, 2016 11:34:28 PM Marius Strobl wrote: > > > Author: marius > > > Date: Tue Jan 19 23:34:27 2016 > > > New Revision: 294362 > > > URL: https://svnweb.freebsd.org/changeset/base/294362 > > > > > > Log: > > > Fix tty_drain() and, thus, TIOCDRAIN of the current tty(4) incarnation > > > to actually wait until the TX FIFOs of UARTs have be drained before > > > returning. This is done by bringing the equivalent of the TS_BUSY flag > > > found in the previous implementation back in an ABI-preserving way. > > > Reported and tested by: Patrick Powell > > > > > > Most likely, drivers for USB-serial-adapters likewise incorporating > > > TX FIFOs as well as other terminal devices that buffer output in some > > > form should also provide implementations of tsw_busy. > > > > > > MFC after: 3 days > > > > Hmm, I got a panic on boot that I think is from this: > > > > panic: Assertion tty_gone(tp) failed at /ufs/src-head-clean/sys/sys/ttydevsw.h:19 > > cpuid = 8 > > KDB: stack backtrace: > > db_trace_self_wrapper() at db_trace_self_wrapper+0x2b/frame 0xfffffe085c93a430 > > vpanic() at vpanic+0x182/frame 0xfffffe085c93a4b0 > > kassert_panic() at kassert_panic+0x126/frame 0xfffffe085c93a520 > > tty_drain() at tty_drain+0x80/frame 0xfffffe085c93a560 > > ttydev_leave() at ttydev_leave+0x8d/frame 0xfffffe085c93a580 > > ttydev_close() at ttydev_close+0xaf/frame 0xfffffe085c93a5a0 > > devfs_close() at devfs_close+0x223/frame 0xfffffe085c93a610 > > VOP_CLOSE_APV() at VOP_CLOSE_APV+0xf1/frame 0xfffffe085c93a640 > > vn_close() at vn_close+0xcd/frame 0xfffffe085c93a6b0 > > vn_closefile() at vn_closefile+0x4a/frame 0xfffffe085c93a730 > > devfs_close_f() at devfs_close_f+0x2c/frame 0xfffffe085c93a760 > > _fdrop() at _fdrop+0x1a/frame 0xfffffe085c93a780 > > closef() at closef+0x1e1/frame 0xfffffe085c93a810 > > fdescfree_fds() at fdescfree_fds+0x9d/frame 0xfffffe085c93a850 > > fdescfree() at fdescfree+0x46c/frame 0xfffffe085c93a910 > > exit1() at exit1+0x4e6/frame 0xfffffe085c93a990 > > sys_sys_exit() at sys_sys_exit+0xd/frame 0xfffffe085c93a9a0 > > amd64_syscall() at amd64_syscall+0x2db/frame 0xfffffe085c93aab0 > > (kgdb) frame 4 > #4 0xffffffff80a93360 in tty_drain (tp=0xfffff8000b9c9800, leaving=1) > at ttydevsw.h:191 > 191 MPASS(tty_gone(tp)); > Current language: auto; currently minimal > (kgdb) p tp > $1 = (struct tty *) 0xfffff8000b9c9800 > (kgdb) p *tp > $2 = {t_mtx = 0xfffff8000b9c9808, t_mtxobj = {lock_object = { > lo_name = 0xffffffff81389f66 "ttymtx", lo_flags = 16973824, lo_data = 0, > lo_witness = 0xfffffe0000bafd80}, mtx_lock = 18446735277934809088}, > t_list = {tqe_next = 0xfffff8000b9c9400, tqe_prev = 0xfffff8000b9c9c28}, > t_flags = 128, t_revokecnt = 1, t_inq = {ti_firstblock = 0xfffff8001f5c86e0, > ti_startblock = 0x0, ti_reprintblock = 0x0, ti_lastblock = 0x0, > ti_begin = 0, ti_linestart = 0, ti_reprint = 0, ti_end = 0, > ti_nblocks = 15, ti_quota = 15}, t_inlow = 1728, t_outq = { > to_firstblock = 0xfffff8001f4b0900, to_lastblock = 0x0, to_begin = 0, > to_end = 0, to_nblocks = 8, to_quota = 8}, t_outlow = 1785, t_inwait = { > cv_description = 0xffffffff81389f45 "ttyin", cv_waiters = 0}, t_outwait = { > cv_description = 0xffffffff81389f4b "ttyout", cv_waiters = 0}, > t_outserwait = {cv_description = 0xffffffff81389f52 "ttyosr", > cv_waiters = 0}, t_bgwait = {cv_description = 0xffffffff81389f59 "ttybg", > cv_waiters = 0}, t_dcdwait = { > cv_description = 0xffffffff81389f5f "ttydcd", cv_waiters = 0}, t_inpoll = { > si_tdlist = {tqh_first = 0x0, tqh_last = 0x0}, si_note = {kl_list = { > slh_first = 0x0}, kl_lock = 0xffffffff809dd1e0 <knlist_mtx_lock>, > kl_unlock = 0xffffffff809dd200 <knlist_mtx_unlock>, > kl_assert_locked = 0xffffffff809dd220 <knlist_mtx_assert_locked>, > kl_assert_unlocked = 0xffffffff809dd240 <knlist_mtx_assert_unlocked>, > kl_lockarg = 0xfffff8000b9c9808}, si_mtx = 0x0}, t_outpoll = { > si_tdlist = {tqh_first = 0x0, tqh_last = 0x0}, si_note = {kl_list = { > slh_first = 0x0}, kl_lock = 0xffffffff809dd1e0 <knlist_mtx_lock>, > kl_unlock = 0xffffffff809dd200 <knlist_mtx_unlock>, > ---Type <return> to continue, or q <return> to quit--- > kl_assert_locked = 0xffffffff809dd220 <knlist_mtx_assert_locked>, > kl_assert_unlocked = 0xffffffff809dd240 <knlist_mtx_assert_unlocked>, > kl_lockarg = 0xfffff8000b9c9808}, si_mtx = 0x0}, t_sigio = 0x0, > t_termios = {c_iflag = 11010, c_oflag = 3, c_cflag = 19200, c_lflag = 1483, > c_cc = 0xfffff8000b9c99a0 "\004��\177\027\025\022\b\003\034\032\031\021\023\026\017\001", c_ispeed = 9600, c_ospeed = 9600}, t_winsize = {ws_row = 30, > ws_col = 80, ws_xpixel = 640, ws_ypixel = 480}, t_column = 0, > t_writepos = 0, t_compatflags = 0, t_termios_init_in = {c_iflag = 11010, > c_oflag = 3, c_cflag = 19200, c_lflag = 1483, > c_cc = 0xfffff8000b9c99e0 "\004��\177\027\025\022\b\003\034\032\031\021\023\026\017\001", c_ispeed = 9600, c_ospeed = 9600}, t_termios_lock_in = { > c_iflag = 0, c_oflag = 0, c_cflag = 0, c_lflag = 0, > c_cc = 0xfffff8000b9c9a0c "", c_ispeed = 0, c_ospeed = 0}, > t_termios_init_out = {c_iflag = 11010, c_oflag = 3, c_cflag = 19200, > c_lflag = 1483, > c_cc = 0xfffff8000b9c9a38 "\004��\177\027\025\022\b\003\034\032\031\021\023\026\017\001", c_ispeed = 9600, c_ospeed = 9600}, t_termios_lock_out = { > c_iflag = 0, c_oflag = 0, c_cflag = 0, c_lflag = 0, > c_cc = 0xfffff8000b9c9a64 "", c_ispeed = 0, c_ospeed = 0}, > t_devsw = 0xffffffff81885300, t_hook = 0x0, t_pgrp = 0x0, t_session = 0x0, > t_sessioncnt = 0, t_devswsoftc = 0xffffffff8185bd88, t_hooksoftc = 0x0, > t_dev = 0xfffff8000b9d4400} > (kgdb) p tp->t_dev > $3 = (struct cdev *) 0xfffff8000b9d4400 > (kgdb) p tp->t_dev->si_name > $4 = 0xfffff8000b9d44e0 "ttyv0" > > The code in ttydev_leave() is: > > /* Drain any output. */ > MPASS((tp->t_flags & TF_STOPPED) == 0); > if (!tty_gone(tp)) > tty_drain(tp, 1); > > Nothing in tty_drain() sets TF_GONE yet, so this seems to be a guaranteed > panic. > > Various other places also call tty_drain() when then tty is not "gone" > including the ioctl's backing tcsetattr(). On a whim, I inverted the assertion and this booted ok for me: Index: sys/sys/ttydevsw.h =================================================================== --- sys/sys/ttydevsw.h (revision 294367) +++ sys/sys/ttydevsw.h (working copy) @@ -188,7 +188,7 @@ ttydevsw_busy(struct tty *tp) { - MPASS(tty_gone(tp)); + MPASS(!tty_gone(tp)); return (tp->t_devsw->tsw_busy(tp)); } -- John Baldwin
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