linux.git/drivers/tty, branch v3.14.29

n_tty: Fix read_buf race condition, increment read_head after pushing data

2015-01-16T14:59:32+00:00

commit 8bfbe2de769afda051c56aba5450391670e769fc upstream.

Commit 19e2ad6a09f0c06dbca19c98e5f4584269d913dd ("n_tty: Remove overflow
tests from receive_buf() path") moved the increment of read_head into
the arguments list of read_buf_addr(). Function calls represent a
sequence point in C. Therefore read_head is incremented before the
character c is placed in the buffer. Since the circular read buffer is
a lock-less design since commit 6d76bd2618535c581f1673047b8341fd291abc67
("n_tty: Make N_TTY ldisc receive path lockless"), this creates a race
condition that leads to communication errors.

This patch modifies the code to increment read_head _after_ the data
is placed in the buffer and thus fixes the race for non-SMP machines.
To fix the problem for SMP machines, memory barriers must be added in
a separate patch.

Signed-off-by: Christian Riesch 
Signed-off-by: Greg Kroah-Hartman

serial: samsung: wait for transfer completion before clock disable

2015-01-16T14:59:32+00:00

commit 1ff383a4c3eda8893ec61b02831826e1b1f46b41 upstream.

This patch adds waiting until transmit buffer and shifter will be empty
before clock disabling.

Without this fix it's possible to have clock disabled while data was
not transmited yet, which causes unproper state of TX line and problems
in following data transfers.

Signed-off-by: Robert Baldyga 
Signed-off-by: Greg Kroah-Hartman

tty: Fix high cpu load if tty is unreleaseable

2014-11-14T17:00:10+00:00

commit 37b164578826406a173ca7c20d9ba7430134d23e upstream.

Kernel oops can cause the tty to be unreleaseable (for example, if
n_tty_read() crashes while on the read_wait queue). This will cause
tty_release() to endlessly loop without sleeping.

Use a killable sleep timeout which grows by 2n+1 jiffies over the interval
[0, 120 secs.) and then jumps to forever (but still killable).

NB: killable just allows for the task to be rewoken manually, not
to be terminated.

Signed-off-by: Peter Hurley 
Signed-off-by: Greg Kroah-Hartman

serial: Fix divide-by-zero fault in uart_get_divisor()

2014-11-14T17:00:02+00:00

commit 547039ec502076e60034eeb79611df3433a99b7d upstream.

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 
Signed-off-by: Peter Hurley 
Signed-off-by: Greg Kroah-Hartman

tty: omap-serial: fix division by zero

2014-10-30T16:38:22+00:00

commit dc3187564e61260f49eceb21a4e7eb5e4428e90a upstream.

If the chosen baud rate is large enough (e.g. 3.5 megabaud), the
calculated n values in serial_omap_is_baud_mode16() may become 0. This
causes a division by zero when calculating the difference between
calculated and desired baud rates. To prevent this, cap the n13 and n16
values on 1.

Division by zero in kernel.
[] (unwind_backtrace) from [] (show_stack+0x10/0x14)
[] (show_stack) from [] (Ldiv0+0x8/0x10)
[] (Ldiv0) from [] (serial_omap_baud_is_mode16+0x4c/0x68)
[] (serial_omap_baud_is_mode16) from [] (serial_omap_set_termios+0x90/0x8d8)
[] (serial_omap_set_termios) from [] (uart_change_speed+0xa4/0xa8)
[] (uart_change_speed) from [] (uart_set_termios+0xa0/0x1fc)
[] (uart_set_termios) from [] (tty_set_termios+0x248/0x2c0)
[] (tty_set_termios) from [] (set_termios+0x248/0x29c)
[] (set_termios) from [] (tty_mode_ioctl+0x1c8/0x4e8)
[] (tty_mode_ioctl) from [] (tty_ioctl+0xa94/0xb18)
[] (tty_ioctl) from [] (do_vfs_ioctl+0x4a0/0x560)
[] (do_vfs_ioctl) from [] (SyS_ioctl+0x4c/0x74)
[] (SyS_ioctl) from [] (ret_fast_syscall+0x0/0x30)

Signed-off-by: Frans Klaver 
Signed-off-by: Greg Kroah-Hartman

serial: 8250: Add Quark X1000 to 8250_pci.c

2014-10-15T06:36:43+00:00

commit 1ede7dcca3c4fa15a518ab0473126f9c3e621e4c upstream.

Quark X1000 contains two designware derived 8250 serial ports.
Each port has a unique PCI configuration space consisting of
BAR0:UART BAR1:DMA respectively.

Unlike the standard 8250 the register width is 32 bits for RHR,IER etc
The Quark UART has a fundamental clock @ 44.2368 MHz allowing for a
bitrate of up to about 2.76 megabits per second.

This patch enables standard 8250 mode

Signed-off-by: Bryan O'Donoghue 
Reviewed-by: Heikki Krogerus 
Signed-off-by: Greg Kroah-Hartman

serial: 8250_dma: check the result of TX buffer mapping

2014-10-05T21:52:24+00:00

commit d4089a332883ad969700aac5dd4dd5f1c4fee825 upstream.

Using dma_mapping_error() to make sure the mapping did not
fail.

Signed-off-by: Heikki Krogerus 
Cc: "Petallo, MauriceX R" 
Signed-off-by: Greg Kroah-Hartman

serial: core: Preserve termios c_cflag for console resume

2014-09-05T23:34:14+00:00

commit ae84db9661cafc63d179e1d985a2c5b841ff0ac4 upstream.

When a tty is opened for the serial console, the termios c_cflag
settings are inherited from the console line settings.
However, if the tty is subsequently closed, the termios settings
are lost. This results in a garbled console if the console is later
suspended and resumed.

Preserve the termios c_cflag for the serial console when the tty
is shutdown; this reflects the most recent line settings.

Fixes: Bugzilla #69751, 'serial console does not wake from S3'
Reported-by: Valerio Vanni 
Acked-by: Alan Cox 
Signed-off-by: Peter Hurley 
Signed-off-by: Greg Kroah-Hartman

sunsab: Fix detection of BREAK on sunsab serial console

2014-08-14T01:38:26+00:00

[ Upstream commit fe418231b195c205701c0cc550a03f6c9758fd9e ]

Fix detection of BREAK on sunsab serial console: BREAK detection was only
performed when there were also serial characters received simultaneously.
To handle all BREAKs correctly, the check for BREAK and the corresponding
call to uart_handle_break() must also be done if count == 0, therefore
duplicate this code fragment and pull it out of the loop over the received
characters.

Patch applies to 3.16-rc6.

Signed-off-by: Christopher Alexander Tobias Schulze 
Signed-off-by: David S. Miller 
Signed-off-by: Greg Kroah-Hartman

tty: Correct INPCK handling

2014-07-09T18:18:28+00:00

commit 66528f90669691c85c73bea4f0c9f4a5857c4cab upstream.

If INPCK is not set, input parity detection should be disabled. This means
parity errors should not be received from the tty driver, and the data
received should be treated normally.

SUS v3, 11.2.2, General Terminal Interface - Input Modes, states:
  "If INPCK is set, input parity checking shall be enabled. If INPCK is
   not set, input parity checking shall be disabled, allowing output parity
   generation without input parity errors. Note that whether input parity
   checking is enabled or disabled is independent of whether parity detection
   is enabled or disabled (see Control Modes). If parity detection is enabled
   but input parity checking is disabled, the hardware to which the terminal
   is connected shall recognize the parity bit, but the terminal special file
   shall not check whether or not this bit is correctly set."

Ignore parity errors reported by the tty driver when INPCK is not set, and
handle the received data normally.

Fixes: Bugzilla #71681, 'Improvement of n_tty_receive_parity_error from n_tty.c'
Reported-by: Ivan 
Signed-off-by: Peter Hurley 
Signed-off-by: Greg Kroah-Hartman