linux-toradex.git/drivers/tty/n_tty.c, branch v3.13

n_tty: Fix apparent order of echoed output

2013-12-17T17:56:42+00:00

With block processing of echoed output, observed output order is still
required. Push completed echoes and echo commands prior to output.

Introduce echo_mark echo buffer index, which tracks completed echo
commands; ie., those submitted via commit_echoes but which may not
have been committed. Ensure that completed echoes are output prior
to subsequent terminal writes in process_echoes().

Fixes newline/prompt output order in cooked mode shell.

Cc:  # 3.12.x : 39434ab n_tty: Fix missing newline echo
Reported-by: Karl Dahlke 
Reported-by: Mikulas Patocka 
Signed-off-by: Peter Hurley 
Tested-by: Karl Dahlke 
Signed-off-by: Greg Kroah-Hartman

n_tty: Fix missing newline echo

2013-11-29T20:53:19+00:00

When L_ECHONL is on, newlines are echoed regardless of the L_ECHO
state; if set, ensure accumulated echoes are flushed before finishing
the current input processing and before more output.

Cc:  # 3.12.x
Reported-by: Jason Gunthorpe 
Signed-off-by: Peter Hurley 
Signed-off-by: Greg Kroah-Hartman

n_tty: Protect minimum_to_wake reset for concurrent readers

2013-11-25T17:17:49+00:00

With multiple, concurrent readers (each waiting to acquire the
atomic_read_lock mutex), a departing reader may mistakenly reset
minimum_to_wake after a new reader has already set a new value.

Protect the minimum_to_wake reset with the atomic_read_lock critical
section.

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

n_tty: Fix 4096-byte canonical reads

2013-11-25T16:36:56+00:00

Although the maximum allowable canonical line is specified to
be 255 bytes (MAX_CANON), the practical limit has actually been
the size of the line discipline read buffer (N_TTY_BUF_SIZE == 4096).

Commit 32f13521ca68bc624ff6effc77f308a52b038bf0,
n_tty: Line copy to user buffer in canonical mode, limited the
line copy to 4095 bytes. With a completely full line discipline
read buffer and a userspace buffer > 4095, _no_ data was copied,
and the read() syscall returned 0, indicating EOF.

Fix the interval arithmetic to compute the correct number of bytes
to copy to userspace in the range [1..4096].

Cc:  # 3.12.x
Signed-off-by: Peter Hurley 
Signed-off-by: Greg Kroah-Hartman

n_tty: Fix echo overrun tail computation

2013-11-25T16:35:00+00:00

Commit cbfd0340ae1993378fd47179db949e050e16e697,
'n_tty: Process echoes in blocks', introduced an error when
consuming the echo buffer tail to prevent buffer overrun, where
the incorrect operation code byte is checked to determine how
far to advance the tail to the next echo byte.

Check the correct byte for the echo operation code byte.

Cc:  # 3.12.x : c476f65 tty: incorrect test of echo_buf() result for ECHO_OP_START
Cc:  # 3.12.x
Signed-off-by: Peter Hurley 
Signed-off-by: Greg Kroah-Hartman

n_tty: Ensure reader restarts worker for next reader

2013-11-25T16:35:00+00:00

A departing reader must restart a flush_to_ldisc() worker _before_
the next reader enters the read loop; this is to avoid the new reader
concluding no more i/o is available and prematurely exiting, when the
old reader simply hasn't re-started the worker yet.

Cc: stable  # 3.12
Signed-off-by: Peter Hurley 
Signed-off-by: Greg Kroah-Hartman

tty: incorrect test of echo_buf() result for ECHO_OP_START

2013-10-16T20:12:13+00:00

test echo_buf() result for ECHO_OP_START

Signed-off-by: Roel Kluin 
Acked-by: Peter Hurley 
Signed-off-by: Greg Kroah-Hartman

Merge 3.12-rc4 into tty-next

2013-10-07T00:28:16+00:00

We want the tty fixes in this branch as well.

Signed-off-by: Greg Kroah-Hartman

tty: Fix pty master read() after slave closes

2013-10-01T02:05:56+00:00

Commit f95499c3030fe1bfad57745f2db1959c5b43dca8,
  n_tty: Don't wait for buffer work in read() loop
creates a race window which can cause a pty master read()
to miss the last pty slave write(s) and return -EIO instead,
thus signalling the pty slave is closed. This can happen when
the pty slave is written and immediately closed but before the
tty buffer i/o loop receives the new input; the pty master
read() is scheduled, sees its read buffer is empty and the
pty slave has been closed, and exits.

Because tty_flush_to_ldisc() has significant performance impact
for parallel i/o, rather than revert the commit, special case this
condition (ie., when the read buffer is empty and the 'other' pty
has been closed) and, only then, wait for buffer work to complete
before re-testing if the read buffer is still empty.

As before, subsequent pty master reads return any available data
until no more data is available, and then returns -EIO to
indicate the pty slave has closed.

Reported-by: Mikael Pettersson 
Signed-off-by: Peter Hurley 
Tested-by: Mikael Pettersson 
Signed-off-by: Greg Kroah-Hartman

Merge 3.12-rc3 into tty-next

2013-09-30T01:44:13+00:00

We want the tty/serial fixes in here as well.

Signed-off-by: Greg Kroah-Hartman