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commit fb2b90014d782d80d7ebf663e50f96d8c507a73c upstream.
There seems to be a race condition in tty drivers and I could see on
many boot cycles a NULL pointer dereference as tty_init_dev() tries to
do 'tty->port->itty = tty' even though tty->port is NULL.
'tty->port' will be set by the driver and if the driver has not yet done
it before we open the tty device we can get to this situation. By adding
some extra debug prints, I noticed that:
6.650130: uart_add_one_port
6.663849: register_console
6.664846: tty_open
6.674391: tty_init_dev
6.675456: tty_port_link_device
uart_add_one_port() registers the console, as soon as it registers, the
userspace tries to use it and that leads to tty_open() but
uart_add_one_port() has not yet done tty_port_link_device() and so
tty->port is not yet configured when control reaches tty_init_dev().
Further look into the code and tty_port_link_device() is done by
uart_add_one_port(). After registering the console uart_add_one_port()
will call tty_port_register_device_attr_serdev() and
tty_port_link_device() is called from this.
Call add tty_port_link_device() before uart_configure_port() is done and
add a check in tty_port_link_device() so that it only links the port if
it has not been done yet.
Suggested-by: Jiri Slaby <jslaby@suse.com>
Signed-off-by: Sudip Mukherjee <sudipm.mukherjee@gmail.com>
Cc: stable <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20191212131602.29504-1-sudipm.mukherjee@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 7d73170e1c282576419f8b50a771f1fcd2b81a94 upstream.
Doing fuzz test on sbsa uart device, causes a kernel crash
due to NULL pointer dereference:
------------[ cut here ]------------
Unable to handle kernel paging request at virtual address fffffffffffffffc
pgd = ffffffe331723000
[fffffffffffffffc] *pgd=0000002333595003, *pud=0000002333595003, *pmd=00000
Internal error: Oops: 96000005 [#1] PREEMPT SMP
Modules linked in: ping(O) jffs2 rtos_snapshot(O) pramdisk(O) hisi_sfc(O)
Drv_Nandc_K(O) Drv_SysCtl_K(O) Drv_SysClk_K(O) bsp_reg(O) hns3(O)
hns3_uio_enet(O) hclgevf(O) hclge(O) hnae3(O) mdio_factory(O)
mdio_registry(O) mdio_dev(O) mdio(O) hns3_info(O) rtos_kbox_panic(O)
uart_suspend(O) rsm(O) stp llc tunnel4 xt_tcpudp ipt_REJECT nf_reject_ipv4
iptable_filter ip_tables x_tables sd_mod xhci_plat_hcd xhci_pci xhci_hcd
usbmon usbhid usb_storage ohci_platform ohci_pci ohci_hcd hid_generic hid
ehci_platform ehci_pci ehci_hcd vfat fat usbcore usb_common scsi_mod
yaffs2multi(O) ext4 jbd2 ext2 mbcache ofpart i2c_dev i2c_core uio ubi nand
nand_ecc nand_ids cfi_cmdset_0002 cfi_cmdset_0001 cfi_probe gen_probe
cmdlinepart chipreg mtdblock mtd_blkdevs mtd nfsd auth_rpcgss oid_registry
nfsv3 nfs nfs_acl lockd sunrpc grace autofs4
CPU: 2 PID: 2385 Comm: tty_fuzz_test Tainted: G O 4.4.193 #1
task: ffffffe32b23f110 task.stack: ffffffe32bda4000
PC is at uart_break_ctl+0x44/0x84
LR is at uart_break_ctl+0x34/0x84
pc : [<ffffff8393196098>] lr : [<ffffff8393196088>] pstate: 80000005
sp : ffffffe32bda7cc0
x29: ffffffe32bda7cc0 x28: ffffffe32b23f110
x27: ffffff8393402000 x26: 0000000000000000
x25: ffffffe32b233f40 x24: ffffffc07a8ec680
x23: 0000000000005425 x22: 00000000ffffffff
x21: ffffffe33ed73c98 x20: 0000000000000000
x19: ffffffe33ed94168 x18: 0000000000000004
x17: 0000007f92ae9d30 x16: ffffff8392fa6064
x15: 0000000000000010 x14: 0000000000000000
x13: 0000000000000000 x12: 0000000000000000
x11: 0000000000000020 x10: 0000007ffdac1708
x9 : 0000000000000078 x8 : 000000000000001d
x7 : 0000000052a64887 x6 : ffffffe32bda7e08
x5 : ffffffe32b23c000 x4 : 0000005fbc5b0000
x3 : ffffff83938d5018 x2 : 0000000000000080
x1 : ffffffe32b23c040 x0 : ffffff83934428f8
virtual start addr offset is 38ac00000
module base offset is 2cd4cf1000
linear region base offset is : 0
Process tty_fuzz_test (pid: 2385, stack limit = 0xffffffe32bda4000)
Stack: (0xffffffe32bda7cc0 to 0xffffffe32bda8000)
7cc0: ffffffe32bda7cf0 ffffff8393177718 ffffffc07a8ec680 ffffff8393196054
7ce0: 000000001739f2e0 0000007ffdac1978 ffffffe32bda7d20 ffffff8393179a1c
7d00: 0000000000000000 ffffff8393c0a000 ffffffc07a8ec680 cb88537fdc8ba600
7d20: ffffffe32bda7df0 ffffff8392fa5a40 ffffff8393c0a000 0000000000005425
7d40: 0000007ffdac1978 ffffffe32b233f40 ffffff8393178dcc 0000000000000003
7d60: 000000000000011d 000000000000001d ffffffe32b23f110 000000000000029e
7d80: ffffffe34fe8d5d0 0000000000000000 ffffffe32bda7e14 cb88537fdc8ba600
7da0: ffffffe32bda7e30 ffffff8393042cfc ffffff8393c41720 ffffff8393c46410
7dc0: ffffff839304fa68 ffffffe32b233f40 0000000000005425 0000007ffdac1978
7de0: 000000000000011d cb88537fdc8ba600 ffffffe32bda7e70 ffffff8392fa60cc
7e00: 0000000000000000 ffffffe32b233f40 ffffffe32b233f40 0000000000000003
7e20: 0000000000005425 0000007ffdac1978 ffffffe32bda7e70 ffffff8392fa60b0
7e40: 0000000000000280 ffffffe32b233f40 ffffffe32b233f40 0000000000000003
7e60: 0000000000005425 cb88537fdc8ba600 0000000000000000 ffffff8392e02e78
7e80: 0000000000000280 0000005fbc5b0000 ffffffffffffffff 0000007f92ae9d3c
7ea0: 0000000060000000 0000000000000015 0000000000000003 0000000000005425
7ec0: 0000007ffdac1978 0000000000000000 00000000a54c910e 0000007f92b95014
7ee0: 0000007f92b95090 0000000052a64887 000000000000001d 0000000000000078
7f00: 0000007ffdac1708 0000000000000020 0000000000000000 0000000000000000
7f20: 0000000000000000 0000000000000010 000000556acf0090 0000007f92ae9d30
7f40: 0000000000000004 000000556acdef10 0000000000000000 000000556acdebd0
7f60: 0000000000000000 0000000000000000 0000000000000000 0000000000000000
7f80: 0000000000000000 0000000000000000 0000000000000000 0000007ffdac1840
7fa0: 000000556acdedcc 0000007ffdac1840 0000007f92ae9d3c 0000000060000000
7fc0: 0000000000000000 0000000000000000 0000000000000003 000000000000001d
7fe0: 0000000000000000 0000000000000000 0000000000000000 0000000000000000
Call trace:
Exception stack(0xffffffe32bda7ab0 to 0xffffffe32bda7bf0)
7aa0: 0000000000001000 0000007fffffffff
7ac0: ffffffe32bda7cc0 ffffff8393196098 0000000080000005 0000000000000025
7ae0: ffffffe32b233f40 ffffff83930d777c ffffffe32bda7b30 ffffff83930d777c
7b00: ffffffe32bda7be0 ffffff83938d5000 ffffffe32bda7be0 ffffffe32bda7c20
7b20: ffffffe32bda7b60 ffffff83930d777c ffffffe32bda7c10 ffffff83938d5000
7b40: ffffffe32bda7c10 ffffffe32bda7c50 ffffff8393c0a000 ffffffe32b23f110
7b60: ffffffe32bda7b70 ffffff8392e09df4 ffffffe32bda7bb0 cb88537fdc8ba600
7b80: ffffff83934428f8 ffffffe32b23c040 0000000000000080 ffffff83938d5018
7ba0: 0000005fbc5b0000 ffffffe32b23c000 ffffffe32bda7e08 0000000052a64887
7bc0: 000000000000001d 0000000000000078 0000007ffdac1708 0000000000000020
7be0: 0000000000000000 0000000000000000
[<ffffff8393196098>] uart_break_ctl+0x44/0x84
[<ffffff8393177718>] send_break+0xa0/0x114
[<ffffff8393179a1c>] tty_ioctl+0xc50/0xe84
[<ffffff8392fa5a40>] do_vfs_ioctl+0xc4/0x6e8
[<ffffff8392fa60cc>] SyS_ioctl+0x68/0x9c
[<ffffff8392e02e78>] __sys_trace_return+0x0/0x4
Code: b9410ea0 34000160 f9408aa0 f9402814 (b85fc280)
---[ end trace 8606094f1960c5e0 ]---
Kernel panic - not syncing: Fatal exception
Fix this problem by adding NULL checks prior to calling break_ctl ops.
Signed-off-by: Jiangfeng Xiao <xiaojiangfeng@huawei.com>
Cc: stable <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/1574263133-28259-1-git-send-email-xiaojiangfeng@huawei.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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With the removal of tty_wait_until_sent_from_close(), tty drivers
no longer wait during open for parallel closes to complete (instead,
the tty core waits before calling the driver open() method). Thus,
the close_wait waitqueue is no longer used for waiting.
Remove struct tty_port::close_wait.
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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There are three natural ways in which devices may be wired to the system:
little endian (device receives correctly ordered bits of a word written
by little-endian CPU to its register, but big-endian CPU needs to swap
bytes of a word before writing it), big endian (same, but with big-endian
CPU in more favourable position) and native endian (CPU of either
endianness may do word-sized I/O without need for byteswapping).
Adding an option for native endianness allows using single kernel command
line for boards with native-endian serial ports on bi-endian
architectures. This goes in parallel with 'native-endian' DTS attribute.
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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serial core does not use tty_port_open() or tty_port_close(); serial
core defines and extends it's own tty open() and close() methods
(uart_open() and uart_close(), respectively).
Remove the tty_port activate() and shutdown() initializations, and
the uart_port_activate() function, which is never called.
NB: uart_port_shutdown() is used by uart_close() => uart_shutdown()
call chain (but not via the tty_port methods).
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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uart_close() runs in non-atomic context only; use
spin_lock/unlock_irq instead of saving the interrupt state (which
== on).
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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While closing, new rx data may be received after the input buffers
have been flushed but before stop_rx() halts receiving [1]. The
new data might not be processed by flush_to_ldisc() until after
uart_shutdown() and normal input processing is re-enabled (ie.,
tty->closing = 0). The race is outlined below:
CPU 0 | CPU 1
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uart_close() |
tty_port_close_start() |
tty->closing = 1 |
tty_ldisc_flush() |
| => IRQ
| while (LSR & data ready)
| uart_insert_char()
| tty_flip_buffer_push()
| <= EOI
stop_rx() | .
uart_shutdown() | .
free xmit.buf | .
tty_port_tty_set(NULL) | .
tty->closing = 0 | .
| flush_to_ldisc()
| n_tty_receive_buf_common()
| __receive_buf()
| ...
| commit_echoes()
| uart_flush_chars()
| __uart_start()
| ** OOPS on port.tty deref **
tty_ldisc_flush() |
Input processing must be prevented from echoing (tty->closing = 1)
until _after_ the input buffers have been flushed again at the end
of uart_close().
[1] In fact, some input may actually be buffered _after_ stop_rx()
since the rx interrupt may have already triggered but not yet been
handled when stop_rx() disables rx interrupts.
Fixes: 2e758910832d ("serial: core: Flush ldisc after dropping port
mutex in uart_close()")
Reported-by: Robert Elliott <elliott@hp.com>
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Align with coding guidelines:
Replaced a chain of "else if" by a switch case.
Signed-off-by: Joakim Nordell <joakim.nordell@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Support command line parameters of the form:
earlycon=<name>,io|mmio|mmio32|mmio32be,<addr>,<options>
This commit seem to be needed even after commit:
serial: 8250: Add support for big-endian MMIO accesses
c627f2ceb692e8a9358b64ac2d139314e7bb0d17
Signed-off-by: Noam Camus <noamc@ezchip.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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tty_name no longer uses the buf parameter, so remove it along with all
the 64 byte stack buffers that used to be passed in.
Mostly generated by the coccinelle script
@depends on patch@
identifier buf;
constant C;
expression tty;
@@
- char buf[C];
<+...
- tty_name(tty, buf)
+ tty_name(tty)
...+>
allmodconfig compiles, so I'm fairly confident the stack buffers
weren't used for other purposes as well.
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Reviewed-by: Peter Hurley <peter@hurleysoftware.com>
Acked-by: Jesper Nilsson <jesper.nilsson@axis.com>
Acked-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Fix uart_console_write() kernel-doc build warnings.
Warning(drivers/tty/serial/serial_core.c:1778): No description found for parameter 'putchar'
Warning(drivers/tty/serial/serial_core.c:1778): Excess function parameter 'write' description in 'uart_console_write'
Fixes: 1cfe42b7fd29 ("serial: core: Fix kernel doc for uart_console_write()")
Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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'/**' is required to start a kernel-doc comment block.
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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UART drivers that share ttyS namespace cannot trivially compute the
ttyS index from the port->line value since the minor_start may be
offset from minor 64. Further, to do so requires a pointer to the
uart driver since there is no back pointer from uart_port to
uart_driver.
Rather than have UART drivers computing the minor value by themselves,
encapsulate within the serial core at port registration time.
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Prepare to support console-defined matching; refactor the command
line parameter string processing from parse_options() into a
new core function, uart_parse_earlycon(), which decodes command line
parameters of the form:
earlycon=<name>,io|mmio|mmio32,<addr>,<options>
console=<name>,io|mmio|mmio32,<addr>,<options>
earlycon=<name>,0x<addr>,<options>
console=<name>,0x<addr>,<options>
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Use helper functions to access current->state.
Direct assignments are prone to races and therefore buggy.
Thanks to Peter Zijlstra for the exact definition of the problem.
Suggested-By: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Fabian Frederick <fabf@skynet.be>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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hw-assisted flow control support was added to the serial core
in v3.8 with commits,
dba05832cbe4f ("SERIAL: core: add hardware assisted h/w flow control support")
2cbacafd7af0f ("SERIAL: core: add hardware assisted s/w flow control support")
9aba8d5b01119 ("SERIAL: core: add throttle/unthrottle callbacks for hardware
assisted flow control")
Since then, additional requirements for serial core support have arisen.
Specifically,
1. Separate tx and rx flow control settings for UARTs which only support
tx flow control (ie., autoCTS).
2. Disable sw-assisted CTS flow control in autoCTS mode
3. Support for RTS flow control by serial core and userspace in autoRTS mode
Distinguish mode from capability; introduce UPSTAT_AUTORTS, UPSTAT_AUTOCTS
and UPSTAT_AUTOXOFF which, when set by the uart driver, enable serial core
support for hw-assisted rx, hw-assisted tx and hw-assisted in-band/IXOFF
rx flow control, respectively. [Note: hw-assisted in-band/IXON tx flow
control does not require serial core support/intervention and can be
enabled by the uart driver when required.]
These modes must be set/reset in the driver's set_termios() method, based
on termios settings, and thus can be safely queried in any context in which
one of the port lock, port mutex or termios rwsem are held. Set these modes
in the 2 in-tree drivers, omap-serial and 8250_omap, which currently
use UPF_HARD_FLOW/UPF_SOFT_FLOW support.
Retain UPF_HARD_FLOW and UPF_SOFT_FLOW as capabilities; re-define
UPF_HARD_FLOW as both UPF_AUTO_RTS and UPF_AUTO_CTS to allow for distinct
and separate rx and tx flow control capabilities.
Disable sw-assisted CTS flow control when UPSTAT_AUTOCTS is enabled.
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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When the uart port being suspended is a console and consoles are
not suspending (kernel command line contains no_console_suspend),
then no action is performed for that port, and the function can
return early.
If the function has not returned early, then one of the conditions
is not true, so the expression
(console_suspend_enabled || !uart_console(uport))
must be true and can be eliminated.
Similarly, the expression
(console_suspend_enabled && uart_console(uport))
simplifies to just uart_console(uport).
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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This is a partial revert of 2f2dafe (serial: serial_core.c: printk
replacement) which gets us booting again. The real problem seems to be
the _emit path in early boot. However, until we can root cause it, we
need at least to get boot working.
Fixes: 2f2dafe77df2c78e189a9fa6b1879dffd06ae5a1
Cc: stable@vger.kernel.org
Signed-off-by: James Bottomley <JBottomley@Parallels.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Since most drivers interpret UPIO_MEM32 to mean "little-endian" and use
readl/writel to access the registers, add a parallel UPIO_MEM32BE to
request the use of big-endian MMIO accessors (ioread32be/iowrite32be).
Signed-off-by: Kevin Cernekee <cernekee@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Introduce an homogeneous lock system between setting and using the rs485
data of the uart_port.
This patch should not be split into multiple ones in order to avoid
leaving the tree in an unstable state.
Acked-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Reviewed-by: Alan Cox <alan@linux.intel.com>
Suggested-by: Alan Cox <alan@linux.intel.com>
Cc: Nicolas Ferre <nicolas.ferre@atmel.com>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk>
Signed-off-by: Ricardo Ribalda Delgado <ricardo.ribalda@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Once there is no more handlers for TIOC[GS]RS485 there is no need to
call the driver specific ioctl when the generic implementation is
missing.
Reviewed-by: Alan Cox <alan@linux.intel.com>
Cc: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Ricardo Ribalda Delgado <ricardo.ribalda@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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The following drivers: 8250_core, atmel_serial, max310x, mcf, omap-serial
and sci16is7xx implement code to handle RS485 ioctls.
In order to avoid code duplication, we implement a simple ioctl handler
on the serial_core layer.
This handler can be used by all the other drivers instead of duplicating
code.
Until this is the only RS485 ioctl handler, it will try first the
rs485_config callback and if it is not present it will call the driver
specific ioctl.
Reviewed-by: Alan Cox <alan@linux.intel.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Ricardo Ribalda Delgado <ricardo.ribalda@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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UART drivers which enable modem status interrupts when switching
to N_PPS line discipline need to determine if modem status
interrupts should be disabled when switching from N_PPS.
Specifically, the set_ldisc() notification needs to evaluate
UART_ENABLE_MS() which requires termios->c_cflag.
Convert in-tree UART drivers to new interface.
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Three UART drivers (8250, atmel & amba-pl010) enable modem status
interrupts if the line discipline is changed to N_PPS. However,
the uart port flags may only be safely modified while holding the
port mutex.
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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We need the fixes in drivers/tty/tty_io.c that were done in there for
future patches in this branch.
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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A port count mismatch occurs if mutex_lock_interruptible()
exits uart_open() and the port has already been opened. This may
prematurely close a port on an open tty. Since uart_close() is _always_
called if uart_open() fails, the port count must be corrected if errors
occur.
Always increment the port count in uart_open(), regardless of errors;
always decrement the port count in uart_close(). Note that
tty_port_close_start() decrements the port count when uart_open()
was successful.
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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uart_start() only claims the port->lock to call __uart_start(),
which does the actual processing. Eliminate the extra acquire/release
in uart_write(); call __uart_start() directly with port->lock already
held.
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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The key function of uart_add_one_port() is to cross-reference the
UART driver's port structure with the serial core's state table;
keep the assignments together and document this crucial association.
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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tty_port_init() initializes close_delay and closing_wait to these
same values; remove.
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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The wrapped line looks wrong and out-of-place; leave it as
>80 char line.
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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The low-level uart driver may modify termios settings to override
settings that are not compatible with the uart, such as CRTSCTS.
Thus, callers of the low-level uart driver's set_termios() method must
hold termios_rwsem write lock to prevent concurrent access to termios,
in case such override occurs.
The termios_rwsem lock requirement does not extend to console setup
(ie., uart_set_options), as console setup cannot race with tty
operations. Nor does this lock requirement extend to functions which
cannot be concurrent with tty ioctls (ie., uart_port_startup() and
uart_resume_port()).
Further, always claim the port mutex to protect hardware
re-reprogramming in the set_termios() uart driver method. Note this
is unnecessary for console initialization in uart_set_options()
which cannot be concurrent with other uart operations.
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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The tty buffers (and any line discipline buffers) must be flushed after
the UART hardware has shutdown; otherwise, a racing open on the same
tty may receive data from the previous session, which is a security
hazard. However, holding the port mutex while flushing the line
discipline buffers creates a lock inversion if the set_termios()
handler takes the port mutex (as it does in the followup patch,
'serial: Fix locking for uart driver set_termios method'.
Flush the ldisc buffers after dropping the port mutex; the tty lock
is still held which prevents a concurrent open() from advancing while
flushing. Since no new rx data is possible after uart_shutdown() until
a new open reinitializes the port, the later flush has no impact on
what data is being discarded.
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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In the context of the final tty & port close, flushing the tx
ring buffer after the hardware has already been shutdown and
the ring buffer freed is neither required nor desirable.
uart_flush_buffer() performs 3 operations:
1. Resets tx ring buffer indices, but the tx ring buffer has
already been freed and the indices are reset if the port is
re-opened.
2. Calls uart driver's flush_buffer() method
5 in-tree uart drivers define flush_buffer() methods:
amba-pl011, atmel-serial, imx, serial-tegra, timbuart
These have been refactored into the shutdown() method, if
required.
3. Kicks the ldisc for more writing, but this is undesirable.
The file handle is being released; any waiting writer will
will be kicked out by tty_release() with a warning. Further,
the N_TTY ldisc may generate SIGIO for a file handle which
is no longer valid.
Cc: Nicolas Ferre <nicolas.ferre@atmel.com>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Laxman Dewangan <ldewangan@nvidia.com>
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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The struct uart_port.flags field is type upf_t, as are the matching
bit definitions. Change local mask variable to type upf_t.
Fixes sparse warnings:
drivers/tty/serial/serial_core.c:620:22: warning: invalid assignment: |=
drivers/tty/serial/serial_core.c:620:22: left side has type unsigned int
drivers/tty/serial/serial_core.c:620:22: right side has type restricted upf_t
drivers/tty/serial/serial_core.c:622:22: warning: invalid assignment: |=
drivers/tty/serial/serial_core.c:622:22: left side has type unsigned int
drivers/tty/serial/serial_core.c:622:22: right side has type restricted upf_t
drivers/tty/serial/serial_core.c:624:17: warning: restricted upf_t degrades to integer
drivers/tty/serial/serial_core.c:626:22: warning: invalid assignment: &=
drivers/tty/serial/serial_core.c:626:22: left side has type unsigned int
drivers/tty/serial/serial_core.c:626:22: right side has type restricted upf_t
drivers/tty/serial/serial_core.c:629:20: warning: restricted upf_t degrades to integer
drivers/tty/serial/serial_core.c:632:20: warning: restricted upf_t degrades to integer
drivers/tty/serial/serial_core.c:643:22: warning: invalid assignment: |=
drivers/tty/serial/serial_core.c:643:22: left side has type unsigned int
drivers/tty/serial/serial_core.c:643:22: right side has type restricted upf_t
drivers/tty/serial/serial_core.c:645:22: warning: invalid assignment: |=
drivers/tty/serial/serial_core.c:645:22: left side has type unsigned int
drivers/tty/serial/serial_core.c:645:22: right side has type restricted upf_t
drivers/tty/serial/serial_core.c:647:17: warning: restricted upf_t degrades to integer
drivers/tty/serial/serial_core.c:649:22: warning: invalid assignment: &=
drivers/tty/serial/serial_core.c:649:22: left side has type unsigned int
drivers/tty/serial/serial_core.c:649:22: right side has type restricted upf_t
drivers/tty/serial/serial_core.c:652:20: warning: restricted upf_t degrades to integer
drivers/tty/serial/serial_core.c:655:20: warning: restricted upf_t degrades to integer
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Commit 299245a145b2ad4cfb4c5432eb1264299f55e7e0,
serial: core: Privatize modem status enable flags, introduced
the upstat_t type and matching bit definitions. The purpose is to
produce sparse warnings if the wrong bit definitions are used
(by warning of implicit integer conversions).
Fix implicit conversion to integer return type from uart_cts_enabled()
and uart_dcd_enabled().
Fixes the following sparse warnings:
drivers/tty/serial/serial_core.c:63:30: warning: incorrect type in return expression (different base types)
drivers/tty/serial/serial_core.c:63:30: expected int
drivers/tty/serial/serial_core.c:63:30: got restricted upstat_t
include/linux/serial_core.h:364:30: warning: incorrect type in return expression (different base types)
include/linux/serial_core.h:364:30: expected bool
include/linux/serial_core.h:364:30: got restricted upstat_t
include/linux/serial_core.h:364:30: warning: incorrect type in return expression (different base types)
include/linux/serial_core.h:364:30: expected bool
include/linux/serial_core.h:364:30: got restricted upstat_t
Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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uart_get_baud_rate() will return baud == 0 if the max rate is set
to the "magic" 38400 rate and the SPD_* flags are also specified.
On the first iteration, if the current baud rate is higher than the
max, the baud rate is clamped at the max (which in the degenerate
case is 38400). On the second iteration, the now-"magic" 38400 baud
rate selects the possibly higher alternate baud rate indicated by
the SPD_* flag. Since only two loop iterations are performed, the
loop is exited, a kernel WARNING is generated and a baud rate of
0 is returned.
Reproducible with:
setserial /dev/ttyS0 spd_hi base_baud 38400
Only perform the "magic" 38400 -> SPD_* baud transform on the first
loop iteration, which prevents the degenerate case from recognizing
the clamped baud rate as the "magic" 38400 value.
Reported-by: Robert Święcki <robert@swiecki.net>
Cc: <stable@vger.kernel.org> # all
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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This reverts commit a86713b1536c818972675e6dd8c6e738f0379f1d.
Kevin Hilman writes:
Multiple boot failures on ARM[1] were bisected down to this
patch.
How was this patch tested, and on which platforms?
Also, the changelog states that this should be done only for
UART_CAP_SLEEP, but the patch does it for every UART.
Greg, I suggest this patch be dropped from tty-next until it has
been better described and tested.
[1] http://lists.linaro.org/pipermail/kernel-build-reports/2014-October/005550.html
Reported-by: Kevin Hilman <khilman@kernel.org>
Cc: Sudhir Sreedharan <ssreedharan@mvista.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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For console devices having UART_CAP_SLEEP capability, the uart_pm_state has
to be initialized to UART_PM_STATE_ON. Otherwise the LCR regiser values
are reinitialized when uart_change_pm is called from uart_configure_port.
Signed-off-by: Sudhir Sreedharan <ssreedharan@mvista.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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uart_set_termios() is called with interrupts enabled; no need to
save and restore the interrupt state when taking the uart port lock.
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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tty->hw_stopped is not used by the tty core and is thread-unsafe;
hw_stopped is a member of a bitfield whose fields are updated
non-atomically and no lock is suitable for serializing updates.
Replace serial core usage of tty->hw_stopped with uport->hw_stopped.
Use int storage which works around Alpha EV4/5 non-atomic byte storage,
since uart_port uses different locks to protect certain fields within the
structure.
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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The serial core uses the tty port flags, ASYNC_CTS_FLOW and
ASYNC_CD_CHECK, to track whether CTS and DCD changes should be
ignored or handled. However, the tty port flags are not safe for
atomic bit operations and no lock provides serialized updates.
Introduce the struct uart_port status field to track CTS and DCD
enable states, and serialize access with uart port lock. Substitute
uart_cts_enabled() helper for tty_port_cts_enabled().
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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The serial core provides two helper functions, uart_handle_dcd_change()
and uart_handle_cts_change(), for UART drivers to use at interrupt
time. The serial core expects the UART driver to hold the uart port lock
when calling these helpers to prevent state corruption.
If lockdep enabled, trigger a warning if the uart port lock is not held
when calling these helper functions.
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Prepare for spin lock assertion; move non-trivial assignment into
function body.
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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uart_unthrottle() attempts to avoid sending START and the previous
x_char if the previous x_char has not yet been sent. However, this
optimization could leave the sender in a throttled state; for example,
if the sender is throttled and this unthrottle coincides with a manual
tcflow(TCION) from user-space, then neither START would be sent.
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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The UART driver is expected to clear port->x_char after
transmission while holding the port->lock. However, the serial
core fails to take the port->lock before assigning port->xchar.
This allows for the following race
CPU 0 | CPU 1
|
| serial8250_handle_irq
| ...
| serial8250_tx_chars
| if (port->x_char)
| serial_out(up, UART_TX, port->x_char)
uart_send_xchar |
port->x_char = ch |
| port->x_char = 0
port->ops->start_tx() |
|
The x_char on CPU 0 will never be sent.
Take the port->lock in uart_send_xchar() before assigning port->x_char.
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Unwrap if() conditional; no functional change.
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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This reverts commit 06aa82e498c144c7784a6f3d3b55458b272d6146.
This commit purports to enable auto CTS flow control for the 8250
UART driver. However, the 8250 UART driver already supports auto
CTS flow control via UART_CAP_AFE and UART_CAP_EFR. Indeed, this
patch introduces another DT attribute for which an existing firmware
flag already exists ("auto-flow-control"). Furthermore, the use of
UPF_HARD_FLOW requires the UART driver to define .throttle and
.unthrottle methods, neither of which are defined for the 8250 UART
driver (which will result in a NULL ptr dereference). Finally, this patch
supposes to fix existing bugs in the serial core for auto CTS-enabled
hardware, but does not include the class of hardware for which these
bugs exist.
CC: Murali Karicheri <m-karicheri2@ti.com>
CC: Rob Herring <robh+dt@kernel.org>
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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printk replaced with corresponding dev_* .
fixed two broken user-visible strings used by the corresponding printk.
the null check for uport->dev and port->dev is removed as dev_* will check for
null while printing.
printing of dev_name(uport->dev) and dev_name(port->dev) also removed as those
are being printed by dev_* .
Signed-off-by: Sudip Mukherjee <sudip@vectorindia.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Pull device tree updates from Grant Likely:
"The branch contains the following device tree changes the v3.17 merge
window:
Group changes to the device tree. In preparation for adding device
tree overlay support, OF_DYNAMIC is reworked so that a set of device
tree changes can be prepared and applied to the tree all at once.
OF_RECONFIG notifiers see the most significant change here so that
users always get a consistent view of the tree. Notifiers generation
is moved from before a change to after it, and notifiers for a group
of changes are emitted after the entire block of changes have been
applied
Automatic console selection from DT. Console drivers can now use
of_console_check() to see if the device node is specified as a console
device. If so then it gets added as a preferred console. UART
devices get this support automatically when uart_add_one_port() is
called.
DT unit tests no longer depend on pre-loaded data in the device tree.
Data is loaded dynamically at the start of unit tests, and then
unloaded again when the tests have completed.
Also contains a few bugfixes for reserved regions and early memory
setup"
* tag 'devicetree-for-linus' of git://git.secretlab.ca/git/linux: (21 commits)
of: Fixing OF Selftest build error
drivers: of: add automated assignment of reserved regions to client devices
of: Use proper types for checking memory overflow
of: typo fix in __of_prop_dup()
Adding selftest testdata dynamically into live tree
of: Add todo tasklist for Devicetree
of: Transactional DT support.
of: Reorder device tree changes and notifiers
of: Move dynamic node fixups out of powerpc and into common code
of: Make sure attached nodes don't carry along extra children
of: Make devicetree sysfs update functions consistent.
of: Create unlocked versions of node and property add/remove functions
OF: Utility helper functions for dynamic nodes
of: Move CONFIG_OF_DYNAMIC code into a separate file
of: rename of_aliases_mutex to just of_mutex
of/platform: Fix of_platform_device_destroy iteration of devices
of: Migrate of_find_node_by_name() users to for_each_node_by_name()
tty: Update hypervisor tty drivers to use core stdout parsing code.
arm/versatile: Add the uart as the stdout device.
of: Enable console on serial ports specified by /chosen/stdout-path
...
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Current code allocates too much data for tty_groups member of uart_port struct,
so fix it.
Signed-off-by: Yoshihiro YUNOMAE <yoshihiro.yunomae.ez@hitachi.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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