From 28b0f8a6962a24ed21737578f3b1b07424635c9e Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Tue, 13 Feb 2018 07:38:08 -0800 Subject: tty: make n_tty_read() always abort if hangup is in progress A tty is hung up by __tty_hangup() setting file->f_op to hung_up_tty_fops, which is skipped on ttys whose write operation isn't tty_write(). This means that, for example, /dev/console whose write op is redirected_tty_write() is never actually marked hung up. Because n_tty_read() uses the hung up status to decide whether to abort the waiting readers, the lack of hung-up marking can lead to the following scenario. 1. A session contains two processes. The leader and its child. The child ignores SIGHUP. 2. The leader exits and starts disassociating from the controlling terminal (/dev/console). 3. __tty_hangup() skips setting f_op to hung_up_tty_fops. 4. SIGHUP is delivered and ignored. 5. tty_ldisc_hangup() is invoked. It wakes up the waits which should clear the read lockers of tty->ldisc_sem. 6. The reader wakes up but because tty_hung_up_p() is false, it doesn't abort and goes back to sleep while read-holding tty->ldisc_sem. 7. The leader progresses to tty_ldisc_lock() in tty_ldisc_hangup() and is now stuck in D sleep indefinitely waiting for tty->ldisc_sem. The following is Alan's explanation on why some ttys aren't hung up. http://lkml.kernel.org/r/20171101170908.6ad08580@alans-desktop 1. It broke the serial consoles because they would hang up and close down the hardware. With tty_port that *should* be fixable properly for any cases remaining. 2. The console layer was (and still is) completely broken and doens't refcount properly. So if you turn on console hangups it breaks (as indeed does freeing consoles and half a dozen other things). As neither can be fixed quickly, this patch works around the problem by introducing a new flag, TTY_HUPPING, which is used solely to tell n_tty_read() that hang-up is in progress for the console and the readers should be aborted regardless of the hung-up status of the device. The following is a sample hung task warning caused by this issue. INFO: task agetty:2662 blocked for more than 120 seconds. Not tainted 4.11.3-dbg-tty-lockup-02478-gfd6c7ee-dirty #28 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. 0 2662 1 0x00000086 Call Trace: __schedule+0x267/0x890 schedule+0x36/0x80 schedule_timeout+0x23c/0x2e0 ldsem_down_write+0xce/0x1f6 tty_ldisc_lock+0x16/0x30 tty_ldisc_hangup+0xb3/0x1b0 __tty_hangup+0x300/0x410 disassociate_ctty+0x6c/0x290 do_exit+0x7ef/0xb00 do_group_exit+0x3f/0xa0 get_signal+0x1b3/0x5d0 do_signal+0x28/0x660 exit_to_usermode_loop+0x46/0x86 do_syscall_64+0x9c/0xb0 entry_SYSCALL64_slow_path+0x25/0x25 The following is the repro. Run "$PROG /dev/console". The parent process hangs in D state. #include #include #include #include #include #include #include #include #include #include #include #include int main(int argc, char **argv) { struct sigaction sact = { .sa_handler = SIG_IGN }; struct timespec ts1s = { .tv_sec = 1 }; pid_t pid; int fd; if (argc < 2) { fprintf(stderr, "test-hung-tty /dev/$TTY\n"); return 1; } /* fork a child to ensure that it isn't already the session leader */ pid = fork(); if (pid < 0) { perror("fork"); return 1; } if (pid > 0) { /* top parent, wait for everyone */ while (waitpid(-1, NULL, 0) >= 0) ; if (errno != ECHILD) perror("waitpid"); return 0; } /* new session, start a new session and set the controlling tty */ if (setsid() < 0) { perror("setsid"); return 1; } fd = open(argv[1], O_RDWR); if (fd < 0) { perror("open"); return 1; } if (ioctl(fd, TIOCSCTTY, 1) < 0) { perror("ioctl"); return 1; } /* fork a child, sleep a bit and exit */ pid = fork(); if (pid < 0) { perror("fork"); return 1; } if (pid > 0) { nanosleep(&ts1s, NULL); printf("Session leader exiting\n"); exit(0); } /* * The child ignores SIGHUP and keeps reading from the controlling * tty. Because SIGHUP is ignored, the child doesn't get killed on * parent exit and the bug in n_tty makes the read(2) block the * parent's control terminal hangup attempt. The parent ends up in * D sleep until the child is explicitly killed. */ sigaction(SIGHUP, &sact, NULL); printf("Child reading tty\n"); while (1) { char buf[1024]; if (read(fd, buf, sizeof(buf)) < 0) { perror("read"); return 1; } } return 0; } Signed-off-by: Tejun Heo Cc: Alan Cox Cc: stable@vger.kernel.org Signed-off-by: Greg Kroah-Hartman --- drivers/tty/n_tty.c | 6 ++++++ drivers/tty/tty_io.c | 9 +++++++++ 2 files changed, 15 insertions(+) (limited to 'drivers/tty') diff --git a/drivers/tty/n_tty.c b/drivers/tty/n_tty.c index 5c0e59e8fe46..cbe98bc2b998 100644 --- a/drivers/tty/n_tty.c +++ b/drivers/tty/n_tty.c @@ -2180,6 +2180,12 @@ static ssize_t n_tty_read(struct tty_struct *tty, struct file *file, } if (tty_hung_up_p(file)) break; + /* + * Abort readers for ttys which never actually + * get hung up. See __tty_hangup(). + */ + if (test_bit(TTY_HUPPING, &tty->flags)) + break; if (!timeout) break; if (file->f_flags & O_NONBLOCK) { diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c index eb9133b472f4..63114ea35ec1 100644 --- a/drivers/tty/tty_io.c +++ b/drivers/tty/tty_io.c @@ -586,6 +586,14 @@ static void __tty_hangup(struct tty_struct *tty, int exit_session) return; } + /* + * Some console devices aren't actually hung up for technical and + * historical reasons, which can lead to indefinite interruptible + * sleep in n_tty_read(). The following explicitly tells + * n_tty_read() to abort readers. + */ + 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 */ @@ -640,6 +648,7 @@ static void __tty_hangup(struct tty_struct *tty, int exit_session) * from the ldisc side, which is now guaranteed. */ set_bit(TTY_HUPPED, &tty->flags); + clear_bit(TTY_HUPPING, &tty->flags); tty_unlock(tty); if (f) -- cgit v1.2.3 From fd63a8903a2c40425a9811c3371dd4d0f42c0ad3 Mon Sep 17 00:00:00 2001 From: Jonas Danielsson Date: Mon, 29 Jan 2018 12:39:15 +0100 Subject: tty/serial: atmel: add new version check for usart On our at91sam9260 based board the usart0 and usart1 ports report their versions (ATMEL_US_VERSION) as 0x10302. This version is not included in the current checks in the driver. Signed-off-by: Jonas Danielsson Acked-by: Richard Genoud Acked-by: Nicolas Ferre Cc: stable Signed-off-by: Greg Kroah-Hartman --- drivers/tty/serial/atmel_serial.c | 1 + 1 file changed, 1 insertion(+) (limited to 'drivers/tty') diff --git a/drivers/tty/serial/atmel_serial.c b/drivers/tty/serial/atmel_serial.c index df46a9e88c34..e287fe8f10fc 100644 --- a/drivers/tty/serial/atmel_serial.c +++ b/drivers/tty/serial/atmel_serial.c @@ -1734,6 +1734,7 @@ static void atmel_get_ip_name(struct uart_port *port) switch (version) { case 0x302: case 0x10213: + case 0x10302: dev_dbg(port->dev, "This version is usart\n"); atmel_port->has_frac_baudrate = true; atmel_port->has_hw_timer = true; -- cgit v1.2.3 From e7f3e99cb1a667d04d60d02957fbed58b50d4e5a Mon Sep 17 00:00:00 2001 From: Andy Shevchenko Date: Fri, 2 Feb 2018 20:39:13 +0200 Subject: serial: 8250_pci: Don't fail on multiport card class Do not fail on multiport cards in serial_pci_is_class_communication(). It restores behaviour for SUNIX multiport cards, that enumerated by class and have a custom board data. Moreover it allows users to reenumerate port-by-port from user space. Fixes: 7d8905d06405 ("serial: 8250_pci: Enable device after we check black list") Reported-by: Nikola Ciprich Signed-off-by: Andy Shevchenko Tested-by: Nikola Ciprich Signed-off-by: Greg Kroah-Hartman --- drivers/tty/serial/8250/8250_pci.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) (limited to 'drivers/tty') diff --git a/drivers/tty/serial/8250/8250_pci.c b/drivers/tty/serial/8250/8250_pci.c index 54adf8d56350..d580625acc79 100644 --- a/drivers/tty/serial/8250/8250_pci.c +++ b/drivers/tty/serial/8250/8250_pci.c @@ -3387,11 +3387,9 @@ static int serial_pci_is_class_communication(struct pci_dev *dev) /* * If it is not a communications device or the programming * interface is greater than 6, give up. - * - * (Should we try to make guesses for multiport serial devices - * later?) */ if ((((dev->class >> 8) != PCI_CLASS_COMMUNICATION_SERIAL) && + ((dev->class >> 8) != PCI_CLASS_COMMUNICATION_MULTISERIAL) && ((dev->class >> 8) != PCI_CLASS_COMMUNICATION_MODEM)) || (dev->class & 0xff) > 6) return -ENODEV; @@ -3428,6 +3426,12 @@ serial_pci_guess_board(struct pci_dev *dev, struct pciserial_board *board) { int num_iomem, num_port, first_port = -1, i; + /* + * Should we try to make guesses for multiport serial devices later? + */ + if ((dev->class >> 8) == PCI_CLASS_COMMUNICATION_MULTISERIAL) + return -ENODEV; + num_iomem = num_port = 0; for (i = 0; i < PCI_NUM_BAR_RESOURCES; i++) { if (pci_resource_flags(dev, i) & IORESOURCE_IO) { -- cgit v1.2.3 From 714569064adee3c114a2a6490735b94abe269068 Mon Sep 17 00:00:00 2001 From: Sebastian Andrzej Siewior Date: Sat, 3 Feb 2018 12:27:23 +0100 Subject: serial: core: mark port as initialized in autoconfig This is a followup on 44117a1d1732 ("serial: core: mark port as initialized after successful IRQ change"). Nikola has been using autoconfig via setserial and reported a crash similar to what I fixed in the earlier mentioned commit. Here I do the same fixup for the autoconfig. I wasn't sure that this is the right approach. Nikola confirmed that it fixes his crash. Fixes: b3b576461864 ("tty: serial_core: convert uart_open to use tty_port_open") Link: http://lkml.kernel.org/r/20180131072000.GD1853@localhost.localdomain Reported-by: Nikola Ciprich Tested-by: Nikola Ciprich Cc: Signed-off-by: Sebastian Andrzej Siewior Tested-by: Nikola Ciprich Acked-by: Johan Hovold Signed-off-by: Greg Kroah-Hartman --- drivers/tty/serial/serial_core.c | 2 ++ 1 file changed, 2 insertions(+) (limited to 'drivers/tty') diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c index c8dde56b532b..35b9201db3b4 100644 --- a/drivers/tty/serial/serial_core.c +++ b/drivers/tty/serial/serial_core.c @@ -1144,6 +1144,8 @@ static int uart_do_autoconfig(struct tty_struct *tty,struct uart_state *state) uport->ops->config_port(uport, flags); ret = uart_startup(tty, state, 1); + if (ret == 0) + tty_port_set_initialized(port, true); if (ret > 0) ret = 0; } -- cgit v1.2.3 From 1f66dd36bb18437397ea0d7882c52f7e3c476e15 Mon Sep 17 00:00:00 2001 From: Greentime Hu Date: Tue, 13 Feb 2018 17:09:08 +0800 Subject: earlycon: add reg-offset to physical address before mapping It will get the wrong virtual address because port->mapbase is not added the correct reg-offset yet. We have to update it before earlycon_map() is called Signed-off-by: Greentime Hu Acked-by: Arnd Bergmann Cc: Peter Hurley Cc: stable@vger.kernel.org Fixes: 088da2a17619 ("of: earlycon: Initialize port fields from DT properties") Acked-by: Rob Herring Signed-off-by: Greg Kroah-Hartman --- drivers/tty/serial/earlycon.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'drivers/tty') diff --git a/drivers/tty/serial/earlycon.c b/drivers/tty/serial/earlycon.c index 870e84fb6e39..a24278380fec 100644 --- a/drivers/tty/serial/earlycon.c +++ b/drivers/tty/serial/earlycon.c @@ -245,11 +245,12 @@ int __init of_setup_earlycon(const struct earlycon_id *match, } port->mapbase = addr; port->uartclk = BASE_BAUD * 16; - port->membase = earlycon_map(port->mapbase, SZ_4K); val = of_get_flat_dt_prop(node, "reg-offset", NULL); if (val) port->mapbase += be32_to_cpu(*val); + port->membase = earlycon_map(port->mapbase, SZ_4K); + val = of_get_flat_dt_prop(node, "reg-shift", NULL); if (val) port->regshift = be32_to_cpu(*val); -- cgit v1.2.3 From 9f2068f35729948bde84d87a40d135015911345d Mon Sep 17 00:00:00 2001 From: Nikola Ciprich Date: Tue, 13 Feb 2018 15:04:46 +0100 Subject: serial: 8250_pci: Add Brainboxes UC-260 4 port serial device Add PCI ids for two variants of Brainboxes UC-260 quad port PCI serial cards. Suggested-by: Andy Shevchenko Signed-off-by: Nikola Ciprich Cc: stable Signed-off-by: Greg Kroah-Hartman --- drivers/tty/serial/8250/8250_pci.c | 11 +++++++++++ 1 file changed, 11 insertions(+) (limited to 'drivers/tty') diff --git a/drivers/tty/serial/8250/8250_pci.c b/drivers/tty/serial/8250/8250_pci.c index d580625acc79..a93f77ab3da0 100644 --- a/drivers/tty/serial/8250/8250_pci.c +++ b/drivers/tty/serial/8250/8250_pci.c @@ -4702,6 +4702,17 @@ static const struct pci_device_id serial_pci_tbl[] = { { PCI_VENDOR_ID_INTASHIELD, PCI_DEVICE_ID_INTASHIELD_IS400, PCI_ANY_ID, PCI_ANY_ID, 0, 0, /* 135a.0dc0 */ pbn_b2_4_115200 }, + /* + * BrainBoxes UC-260 + */ + { PCI_VENDOR_ID_INTASHIELD, 0x0D21, + PCI_ANY_ID, PCI_ANY_ID, + PCI_CLASS_COMMUNICATION_MULTISERIAL << 8, 0xffff00, + pbn_b2_4_115200 }, + { PCI_VENDOR_ID_INTASHIELD, 0x0E34, + PCI_ANY_ID, PCI_ANY_ID, + PCI_CLASS_COMMUNICATION_MULTISERIAL << 8, 0xffff00, + pbn_b2_4_115200 }, /* * Perle PCI-RAS cards */ -- cgit v1.2.3 From 7842055bfce4bf0170d0f61df8b2add8399697be Mon Sep 17 00:00:00 2001 From: Ulrich Hecht Date: Thu, 15 Feb 2018 13:02:27 +0100 Subject: serial: sh-sci: prevent lockup on full TTY buffers When the TTY buffers fill up to the configured maximum, a system lockup occurs: [ 598.820128] INFO: rcu_preempt detected stalls on CPUs/tasks: [ 598.825796] 0-...!: (1 GPs behind) idle=5a6/2/0 softirq=1974/1974 fqs=1 [ 598.832577] (detected by 3, t=62517 jiffies, g=296, c=295, q=126) [ 598.838755] Task dump for CPU 0: [ 598.841977] swapper/0 R running task 0 0 0 0x00000022 [ 598.849023] Call trace: [ 598.851476] __switch_to+0x98/0xb0 [ 598.854870] (null) This can be prevented by doing a dummy read of the RX data register. This issue affects both HSCIF and SCIF ports. Reported for R-Car H3 ES2.0; reproduced and fixed on H3 ES1.1. Probably affects other R-Car platforms as well. Reported-by: Yoshihiro Shimoda Signed-off-by: Ulrich Hecht Reviewed-by: Geert Uytterhoeven Cc: stable Tested-by: Nguyen Viet Dung Signed-off-by: Greg Kroah-Hartman --- drivers/tty/serial/sh-sci.c | 2 ++ 1 file changed, 2 insertions(+) (limited to 'drivers/tty') diff --git a/drivers/tty/serial/sh-sci.c b/drivers/tty/serial/sh-sci.c index 7257c078e155..44adf9db38f8 100644 --- a/drivers/tty/serial/sh-sci.c +++ b/drivers/tty/serial/sh-sci.c @@ -885,6 +885,8 @@ static void sci_receive_chars(struct uart_port *port) /* Tell the rest of the system the news. New characters! */ tty_flip_buffer_push(tport); } else { + /* TTY buffers full; read from RX reg to prevent lockup */ + serial_port_in(port, SCxRDR); serial_port_in(port, SCxSR); /* dummy read */ sci_clear_SCxSR(port, SCxSR_RDxF_CLEAR(port)); } -- cgit v1.2.3 From 5d7f77ec72d10c421bc33958f06a5583f2d27ed6 Mon Sep 17 00:00:00 2001 From: phil eichinger Date: Mon, 19 Feb 2018 10:24:15 +0100 Subject: serial: imx: fix bogus dev_err MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Only one of the two is really required, not both: * have_rtscts or * have_rtsgpio In imx_rs485_config() this is done correctly, so RS485 is working, just the error message is false. Signed-off-by: Phil Eichinger Reviewed-by: Fabio Estevam Fixes: b8f3bff057b0 ("serial: imx: Support common rs485 binding for RTS polarity" Acked-by: Uwe Kleine-König Signed-off-by: Greg Kroah-Hartman --- drivers/tty/serial/imx.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'drivers/tty') diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c index 1d7ca382bc12..a33c685af990 100644 --- a/drivers/tty/serial/imx.c +++ b/drivers/tty/serial/imx.c @@ -2093,7 +2093,7 @@ static int serial_imx_probe(struct platform_device *pdev) uart_get_rs485_mode(&pdev->dev, &sport->port.rs485); if (sport->port.rs485.flags & SER_RS485_ENABLED && - (!sport->have_rtscts || !sport->have_rtsgpio)) + (!sport->have_rtscts && !sport->have_rtsgpio)) dev_err(&pdev->dev, "no RTS control, disabling rs485\n"); imx_rs485_config(&sport->port, &sport->port.rs485); -- cgit v1.2.3