From a80c49dbb6cd389fd5b0d79f850b56322475d00b Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Mon, 15 Nov 2010 21:11:12 +0100 Subject: serial8250: Mark console as CON_ANYTIME While trying to debug a cpu-hotplug issue I noticed printk() stopped working once the cpu got marked offline, since the 8250 serial console doesn't have any per-cpu resources the CON_ANYTIME bit is the safe and documented way to make it work again. Signed-off-by: Peter Zijlstra Signed-off-by: Greg Kroah-Hartman --- drivers/serial/8250.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'drivers') diff --git a/drivers/serial/8250.c b/drivers/serial/8250.c index 4d8e14b7aa93..09a550860dcf 100644 --- a/drivers/serial/8250.c +++ b/drivers/serial/8250.c @@ -2872,7 +2872,7 @@ static struct console serial8250_console = { .device = uart_console_device, .setup = serial8250_console_setup, .early_setup = serial8250_console_early_setup, - .flags = CON_PRINTBUFFER, + .flags = CON_PRINTBUFFER | CON_ANYTIME, .index = -1, .data = &serial8250_reg, }; -- cgit v1.2.3 From 7f90cfc505d613f4faf096e0d84ffe99208057d9 Mon Sep 17 00:00:00 2001 From: Jiri Slaby Date: Thu, 25 Nov 2010 00:27:54 +0100 Subject: TTY: ldisc, fix open flag handling When a concrete ldisc open fails in tty_ldisc_open, we forget to clear TTY_LDISC_OPEN. This causes a false warning on the next ldisc open: WARNING: at drivers/char/tty_ldisc.c:445 tty_ldisc_open+0x26/0x38() Hardware name: System Product Name Modules linked in: ... Pid: 5251, comm: a.out Tainted: G W 2.6.32-5-686 #1 Call Trace: [] ? warn_slowpath_common+0x5e/0x8a [] ? warn_slowpath_null+0xa/0xc [] ? tty_ldisc_open+0x26/0x38 [] ? tty_set_ldisc+0x218/0x304 ... So clear the bit when failing... Introduced in c65c9bc3efa (tty: rewrite the ldisc locking) back in 2.6.31-rc1. Signed-off-by: Jiri Slaby Cc: Alan Cox Reported-by: Sergey Lapin Tested-by: Sergey Lapin Cc: stable Signed-off-by: Greg Kroah-Hartman --- drivers/tty/tty_ldisc.c | 2 ++ 1 file changed, 2 insertions(+) (limited to 'drivers') diff --git a/drivers/tty/tty_ldisc.c b/drivers/tty/tty_ldisc.c index d8e96b005023..4214d58276f7 100644 --- a/drivers/tty/tty_ldisc.c +++ b/drivers/tty/tty_ldisc.c @@ -454,6 +454,8 @@ static int tty_ldisc_open(struct tty_struct *tty, struct tty_ldisc *ld) /* BTM here locks versus a hangup event */ WARN_ON(!tty_locked()); ret = ld->ops->open(tty); + if (ret) + clear_bit(TTY_LDISC_OPEN, &tty->flags); return ret; } return 0; -- cgit v1.2.3 From 6a20bd45fda271bd57e3ba41b3de3009797f4b5e Mon Sep 17 00:00:00 2001 From: Jiri Slaby Date: Thu, 25 Nov 2010 00:27:55 +0100 Subject: NET: wan/x25, fix ldisc->open retval We should never return positive values from ldisc->open, tty layer doesn't (and never did) expect that. If we do that, weird things like warnings in tty_ldisc_close happen. Not sure if dev->base_addr is used somehow now. Signed-off-by: Jiri Slaby Cc: Alan Cox Cc: Andrew Hendry Cc: linux-x25@vger.kernel.org Tested-by: Sergey Lapin Signed-off-by: Greg Kroah-Hartman --- drivers/net/wan/x25_asy.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'drivers') diff --git a/drivers/net/wan/x25_asy.c b/drivers/net/wan/x25_asy.c index d81ad8397885..66cda25aaa26 100644 --- a/drivers/net/wan/x25_asy.c +++ b/drivers/net/wan/x25_asy.c @@ -582,7 +582,7 @@ static int x25_asy_open_tty(struct tty_struct *tty) if (err) return err; /* Done. We have linked the TTY line to a channel. */ - return sl->dev->base_addr; + return 0; } -- cgit v1.2.3 From e2efafbf139d2bfdfe96f2901f03189fecd172e4 Mon Sep 17 00:00:00 2001 From: Jiri Slaby Date: Mon, 29 Nov 2010 10:16:53 +0100 Subject: TTY: don't allow reopen when ldisc is changing There are many WARNINGs like the following reported nowadays: WARNING: at drivers/tty/tty_io.c:1331 tty_open+0x2a2/0x49a() Hardware name: Latitude E6500 Modules linked in: Pid: 1207, comm: plymouthd Not tainted 2.6.37-rc3-mmotm1123 #3 Call Trace: [] warn_slowpath_common+0x80/0x98 [] warn_slowpath_null+0x15/0x17 [] tty_open+0x2a2/0x49a [] chrdev_open+0x11d/0x146 ... This means tty_reopen is called without TTY_LDISC set. For further considerations, note tty_lock is held in tty_open. TTY_LDISC is cleared in: 1) __tty_hangup from tty_ldisc_hangup to tty_ldisc_enable. During this section tty_lock is held. However tty_lock is temporarily dropped in the middle of the function by tty_ldisc_hangup. 2) tty_release via tty_ldisc_release till the end of tty existence. If tty->count <= 1, tty_lock is taken, TTY_CLOSING bit set and then tty_ldisc_release called. tty_reopen checks TTY_CLOSING before checking TTY_LDISC. 3) tty_set_ldisc from tty_ldisc_halt to tty_ldisc_enable. We: * take tty_lock, set TTY_LDISC_CHANGING, put tty_lock * call tty_ldisc_halt (clear TTY_LDISC), tty_lock is _not_ held * do some other work * take tty_lock, call tty_ldisc_enable (set TTY_LDISC), put tty_lock I cannot see how 2) can be a problem, as there I see no race. OTOH, 1) and 3) can happen without problems. This patch the case 3) by checking TTY_LDISC_CHANGING along with TTY_CLOSING in tty_reopen. 1) will be fixed in the following patch. Nicely reproducible with two processes: while (1) { fd = open("/dev/ttyS1", O_RDWR); if (fd < 0) { warn("open"); continue; } close(fd); } -------- while (1) { fd = open("/dev/ttyS1", O_RDWR); ld1 = 0; ld2 = 2; while (1) { ioctl(fd, TIOCSETD, &ld1); ioctl(fd, TIOCSETD, &ld2); } close(fd); } Signed-off-by: Jiri Slaby Reported-by: Cc: Kyle McMartin Cc: Alan Cox Cc: stable Signed-off-by: Greg Kroah-Hartman --- drivers/tty/tty_io.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'drivers') diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c index c05c5af5aa04..878f6d667b17 100644 --- a/drivers/tty/tty_io.c +++ b/drivers/tty/tty_io.c @@ -1310,7 +1310,8 @@ static int tty_reopen(struct tty_struct *tty) { struct tty_driver *driver = tty->driver; - if (test_bit(TTY_CLOSING, &tty->flags)) + if (test_bit(TTY_CLOSING, &tty->flags) || + test_bit(TTY_LDISC_CHANGING, &tty->flags)) return -EIO; if (driver->type == TTY_DRIVER_TYPE_PTY && -- cgit v1.2.3 From acfa747baf73922021a047f2d87a2d866f5dbab5 Mon Sep 17 00:00:00 2001 From: Jiri Slaby Date: Mon, 29 Nov 2010 10:16:54 +0100 Subject: TTY: open/hangup race fixup Like in the "TTY: don't allow reopen when ldisc is changing" patch, this one fixes a TTY WARNING as described in the option 1) there: 1) __tty_hangup from tty_ldisc_hangup to tty_ldisc_enable. During this section tty_lock is held. However tty_lock is temporarily dropped in the middle of the function by tty_ldisc_hangup. The fix is to introduce a new flag which we set during the unlocked window and check it in tty_reopen too. The flag is TTY_HUPPING and is cleared after TTY_HUPPED is set. While at it, remove duplicate TTY_HUPPED set_bit. The one after calling ops->hangup seems to be more correct. But anyway, we hold tty_lock, so there should be no difference. Also document the function it does that kind of crap. Nicely reproducible with two forked children: static void do_work(const char *tty) { if (signal(SIGHUP, SIG_IGN) == SIG_ERR) exit(1); setsid(); while (1) { int fd = open(tty, O_RDWR|O_NOCTTY); if (fd < 0) continue; if (ioctl(fd, TIOCSCTTY)) continue; if (vhangup()) continue; close(fd); } exit(0); } Signed-off-by: Jiri Slaby Reported-by: Reported-by: Kyle McMartin Cc: Alan Cox Cc: stable Signed-off-by: Greg Kroah-Hartman --- drivers/tty/tty_io.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) (limited to 'drivers') diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c index 878f6d667b17..35480dd57a30 100644 --- a/drivers/tty/tty_io.c +++ b/drivers/tty/tty_io.c @@ -559,6 +559,9 @@ void __tty_hangup(struct tty_struct *tty) tty_lock(); + /* some functions below drop BTM, so we need this bit */ + set_bit(TTY_HUPPING, &tty->flags); + /* inuse_filps is protected by the single tty lock, this really needs to change if we want to flush the workqueue with the lock held */ @@ -578,6 +581,10 @@ void __tty_hangup(struct tty_struct *tty) } spin_unlock(&tty_files_lock); + /* + * it drops BTM and thus races with reopen + * we protect the race by TTY_HUPPING + */ tty_ldisc_hangup(tty); read_lock(&tasklist_lock); @@ -615,7 +622,6 @@ void __tty_hangup(struct tty_struct *tty) tty->session = NULL; tty->pgrp = NULL; tty->ctrl_status = 0; - set_bit(TTY_HUPPED, &tty->flags); spin_unlock_irqrestore(&tty->ctrl_lock, flags); /* Account for the p->signal references we killed */ @@ -641,6 +647,7 @@ void __tty_hangup(struct tty_struct *tty) * can't yet guarantee all that. */ set_bit(TTY_HUPPED, &tty->flags); + clear_bit(TTY_HUPPING, &tty->flags); tty_ldisc_enable(tty); tty_unlock(); @@ -1311,6 +1318,7 @@ static int tty_reopen(struct tty_struct *tty) struct tty_driver *driver = tty->driver; if (test_bit(TTY_CLOSING, &tty->flags) || + test_bit(TTY_HUPPING, &tty->flags) || test_bit(TTY_LDISC_CHANGING, &tty->flags)) return -EIO; -- cgit v1.2.3 From a5880a9e5bb40fbae55de60051d69a29091053c3 Mon Sep 17 00:00:00 2001 From: Feng Tang Date: Fri, 19 Nov 2010 11:01:48 +0800 Subject: serial: mfd: adjust the baud rate setting Previous baud rate setting code only has been tested with 3.5M/9600/ 115200/230400/460800 bps, and recently we got a 3M bps device to test, which needs to modify current MUL register setting, and with this patch 2.5M/2M/1.5M/1M/0.5M should also work as they just use a MUL value scale down from 3M's. Also got some reference register setting from silicon guys for different baud rates, which tries to keep the pre-scalar register value to 16. Signed-off-by: Feng Tang Cc: stable Signed-off-by: Greg Kroah-Hartman --- drivers/serial/mfd.c | 24 ++++++++---------------- 1 file changed, 8 insertions(+), 16 deletions(-) (limited to 'drivers') diff --git a/drivers/serial/mfd.c b/drivers/serial/mfd.c index 5fc699e929dc..d40010a22ecd 100644 --- a/drivers/serial/mfd.c +++ b/drivers/serial/mfd.c @@ -900,8 +900,7 @@ serial_hsu_set_termios(struct uart_port *port, struct ktermios *termios, unsigned char cval, fcr = 0; unsigned long flags; unsigned int baud, quot; - u32 mul = 0x3600; - u32 ps = 0x10; + u32 ps, mul; switch (termios->c_cflag & CSIZE) { case CS5: @@ -943,31 +942,24 @@ serial_hsu_set_termios(struct uart_port *port, struct ktermios *termios, baud = uart_get_baud_rate(port, termios, old, 0, 4000000); quot = 1; + ps = 0x10; + mul = 0x3600; switch (baud) { case 3500000: mul = 0x3345; ps = 0xC; break; - case 3000000: - mul = 0x2EE0; - break; - case 2500000: - mul = 0x2710; - break; - case 2000000: - mul = 0x1F40; - break; case 1843200: mul = 0x2400; break; + case 3000000: + case 2500000: + case 2000000: case 1500000: - mul = 0x1770; - break; case 1000000: - mul = 0xFA0; - break; case 500000: - mul = 0x7D0; + /* mul/ps/quot = 0x9C4/0x10/0x1 will make a 500000 bps */ + mul = baud / 500000 * 0x9C4; break; default: /* Use uart_get_divisor to get quot for other baud rates */ -- cgit v1.2.3