Date: Fri, 13 Jan 2017 16:37:38 +0000 (UTC) From: Ian Lepore <ian@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r312077 - in head/sys: kern sys Message-ID: <201701131637.v0DGbcrX051790@repo.freebsd.org>
next in thread | raw e-mail | index | archive | help
Author: ian Date: Fri Jan 13 16:37:38 2017 New Revision: 312077 URL: https://svnweb.freebsd.org/changeset/base/312077 Log: Check tty_gone() after allocating IO buffers. The tty lock has to be dropped then reacquired due to using M_WAITOK, which opens a window in which the tty device can disappear. Check for this and return ENXIO back up the call chain so that callers can cope. This closes a race where TF_GONE would get set while buffers were being allocated as part of ttydev_open(), causing a subsequent call to ttydevsw_modem() later in ttydev_open() to assert. Reported by: pho Reviewed by: kib Modified: head/sys/kern/tty.c head/sys/kern/tty_inq.c head/sys/kern/tty_outq.c head/sys/sys/ttyqueue.h Modified: head/sys/kern/tty.c ============================================================================== --- head/sys/kern/tty.c Fri Jan 13 15:17:25 2017 (r312076) +++ head/sys/kern/tty.c Fri Jan 13 16:37:38 2017 (r312077) @@ -105,25 +105,38 @@ SYSCTL_INT(_kern, OID_AUTO, tty_drainwai #define TTYBUF_MAX 65536 -static void +/* + * Allocate buffer space if necessary, and set low watermarks, based on speed. + * Note that the ttyxxxq_setsize() functions may drop and then reacquire the tty + * lock during memory allocation. They will return ENXIO if the tty disappears + * while unlocked. + */ +static int tty_watermarks(struct tty *tp) { size_t bs = 0; + int error; /* Provide an input buffer for 0.2 seconds of data. */ if (tp->t_termios.c_cflag & CREAD) bs = MIN(tp->t_termios.c_ispeed / 5, TTYBUF_MAX); - ttyinq_setsize(&tp->t_inq, tp, bs); + error = ttyinq_setsize(&tp->t_inq, tp, bs); + if (error != 0) + return (error); /* Set low watermark at 10% (when 90% is available). */ tp->t_inlow = (ttyinq_getallocatedsize(&tp->t_inq) * 9) / 10; /* Provide an output buffer for 0.2 seconds of data. */ bs = MIN(tp->t_termios.c_ospeed / 5, TTYBUF_MAX); - ttyoutq_setsize(&tp->t_outq, tp, bs); + error = ttyoutq_setsize(&tp->t_outq, tp, bs); + if (error != 0) + return (error); /* Set low watermark at 10% (when 90% is available). */ tp->t_outlow = (ttyoutq_getallocatedsize(&tp->t_outq) * 9) / 10; + + return (0); } static int @@ -318,7 +331,9 @@ ttydev_open(struct cdev *dev, int oflags goto done; ttydisc_open(tp); - tty_watermarks(tp); /* XXXGL: drops lock */ + error = tty_watermarks(tp); + if (error != 0) + goto done; } /* Wait for Carrier Detect. */ @@ -1627,7 +1642,9 @@ tty_generic_ioctl(struct tty *tp, u_long tp->t_termios.c_ospeed = t->c_ospeed; /* Baud rate has changed - update watermarks. */ - tty_watermarks(tp); + error = tty_watermarks(tp); + if (error) + return (error); } /* Copy new non-device driver parameters. */ Modified: head/sys/kern/tty_inq.c ============================================================================== --- head/sys/kern/tty_inq.c Fri Jan 13 15:17:25 2017 (r312076) +++ head/sys/kern/tty_inq.c Fri Jan 13 16:37:38 2017 (r312077) @@ -112,7 +112,7 @@ static uma_zone_t ttyinq_zone; TTYINQ_INSERT_TAIL(ti, tib); \ } while (0) -void +int ttyinq_setsize(struct ttyinq *ti, struct tty *tp, size_t size) { struct ttyinq_block *tib; @@ -134,8 +134,14 @@ ttyinq_setsize(struct ttyinq *ti, struct tib = uma_zalloc(ttyinq_zone, M_WAITOK); tty_lock(tp); + if (tty_gone(tp)) { + uma_zfree(ttyinq_zone, tib); + return (ENXIO); + } + TTYINQ_INSERT_TAIL(ti, tib); } + return (0); } void Modified: head/sys/kern/tty_outq.c ============================================================================== --- head/sys/kern/tty_outq.c Fri Jan 13 15:17:25 2017 (r312076) +++ head/sys/kern/tty_outq.c Fri Jan 13 16:37:38 2017 (r312077) @@ -89,7 +89,7 @@ ttyoutq_flush(struct ttyoutq *to) to->to_end = 0; } -void +int ttyoutq_setsize(struct ttyoutq *to, struct tty *tp, size_t size) { struct ttyoutq_block *tob; @@ -111,8 +111,14 @@ ttyoutq_setsize(struct ttyoutq *to, stru tob = uma_zalloc(ttyoutq_zone, M_WAITOK); tty_lock(tp); + if (tty_gone(tp)) { + uma_zfree(ttyoutq_zone, tob); + return (ENXIO); + } + TTYOUTQ_INSERT_TAIL(to, tob); } + return (0); } void Modified: head/sys/sys/ttyqueue.h ============================================================================== --- head/sys/sys/ttyqueue.h Fri Jan 13 15:17:25 2017 (r312076) +++ head/sys/sys/ttyqueue.h Fri Jan 13 16:37:38 2017 (r312077) @@ -69,7 +69,7 @@ struct ttyoutq { #ifdef _KERNEL /* Input queue handling routines. */ -void ttyinq_setsize(struct ttyinq *ti, struct tty *tp, size_t len); +int ttyinq_setsize(struct ttyinq *ti, struct tty *tp, size_t len); void ttyinq_free(struct ttyinq *ti); int ttyinq_read_uio(struct ttyinq *ti, struct tty *tp, struct uio *uio, size_t readlen, size_t flushlen); @@ -136,7 +136,7 @@ void ttyinq_line_iterate_from_reprintpos /* Output queue handling routines. */ void ttyoutq_flush(struct ttyoutq *to); -void ttyoutq_setsize(struct ttyoutq *to, struct tty *tp, size_t len); +int ttyoutq_setsize(struct ttyoutq *to, struct tty *tp, size_t len); void ttyoutq_free(struct ttyoutq *to); size_t ttyoutq_read(struct ttyoutq *to, void *buf, size_t len); int ttyoutq_read_uio(struct ttyoutq *to, struct tty *tp, struct uio *uio);
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?201701131637.v0DGbcrX051790>