linux-toradex.git/drivers/tty/cyclades.c, branch v4.1.10

tty: Remove tty_hung_up_p() tests from tty drivers' open()

2014-07-10T23:06:49+00:00

Since at least before 2.6.30, it has not been possible to observe
a hung up file pointer in a tty driver's open() method unless/until
the driver open() releases the tty_lock() (eg., before blocking).

This is because tty_open() adds the file pointer while holding
the tty_lock() _and_ doesn't release the lock until after calling
the tty driver's open() method. [ Before tty_lock(), this was
lock_kernel(). ]

Since __tty_hangup() first waits on the tty_lock() before
enumerating and hanging up the open file pointers, either
__tty_hangup() will wait for the tty_lock() or tty_open() will
not yet have added the file pointer. For example,

CPU 0                          |  CPU 1
                               |
tty_open                       |  __tty_hangup
  ..                           |    ..
  tty_lock                     |    ..
  tty_reopen                   |    tty_lock  / blocks
  ..                           |
  tty_add_file(tty, filp)      |
  ..                           |
  tty->ops->open(tty, filp)    |
    tty_port_open              |
      tty_port_block_til_ready |
        ..                     |
        while (1)              |
          ..                   |
          tty_unlock           |    / unblocks
          schedule             |    for each filp on tty->tty_files
                               |      f_ops = tty_hung_up_fops;
                               |    ..
                               |    tty_unlock
          tty_lock             |
  ..                           |
  tty_unlock                   |

Note that since tty_port_block_til_ready() and similar drop
the tty_lock while blocking, when woken, the file pointer
must then be tested for having been hung up.

Also, fix bit-rotted drivers that used extra_count to track the
port->count bump.

CC: Mikael Starvik 
CC: Samuel Ortiz 
CC: "David S. Miller" 
Signed-off-by: Peter Hurley 
Acked-by: Jesper Nilsson 
Signed-off-by: Greg Kroah-Hartman

tty: an overflow of multiplication in drivers/tty/cyclades.c

2013-12-20T20:21:57+00:00

there is an overflow in the code :
cyz_polling_cycle = (arg * HZ) / 1000,
the multiplicator arg comes from user, so it may be an overflow if
arg is a big number. And the value of cyc_polling_cycle will be
wrong when it is used next time.

Reported-by: Qixue Xiao 
Suggested-by: Yongjian Xu 
Suggested-by: Yu Chen 
Signed-off-by: Qixue Xiao 
Signed-off-by: Greg Kroah-Hartman

TTY: add tty_port_tty_hangup helper

2013-03-18T23:24:29+00:00

It allows for cleaning up on a considerable amount of places. They did
port_get, hangup, kref_put. Now the only thing needed is to call
tty_port_tty_hangup which does exactly that. And they can also decide
whether to consider CLOCAL or completely ignore that.

Signed-off-by: Jiri Slaby 
Signed-off-by: Greg Kroah-Hartman

cyclades: push down tty_port_tty_get

2013-01-16T06:43:15+00:00

Now, the tty is not needed at all places in the ISR. So we can just
request in on demand when really needed.

This cleans TX and RX paths a bit as the indentation level can be
dropped by two now when we also invert the char_count if condition.

Signed-off-by: Jiri Slaby 
Signed-off-by: Greg Kroah-Hartman

TTY: switch tty_schedule_flip

2013-01-16T06:43:15+00:00

Now, we start converting tty buffer functions to actually use
tty_port. This will allow us to get rid of the need of tty in many
call sites. Only tty_port will needed and hence no more
tty_port_tty_get in those paths.

This is the last one: tty_schedule_flip

Signed-off-by: Jiri Slaby 
Signed-off-by: Greg Kroah-Hartman

TTY: switch tty_insert_flip_char

2013-01-16T06:21:36+00:00

Now, we start converting tty buffer functions to actually use
tty_port. This will allow us to get rid of the need of tty in many
call sites. Only tty_port will needed and hence no more
tty_port_tty_get in those paths.

tty_insert_flip_char is the next one to proceed. This one is used all
over the code, so the patch is huge.

Signed-off-by: Jiri Slaby 
Signed-off-by: Greg Kroah-Hartman

TTY: convert more flipping functions

2013-01-16T06:17:29+00:00

Now, we start converting tty buffer functions to actually use
tty_port. This will allow us to get rid of the need of tty pointer in
many call sites. Only tty_port will be needed and hence no more
tty_port_tty_get calls in those paths.

Now 4 string flipping ones are on turn:
* tty_insert_flip_string_flags
* tty_insert_flip_string_fixed_flag
* tty_prepare_flip_string
* tty_prepare_flip_string_flags

Signed-off-by: Jiri Slaby 
Signed-off-by: Greg Kroah-Hartman

TTY: switch tty_buffer_request_room to tty_port

2013-01-16T06:17:28+00:00

Now, we start converting tty buffer functions to actually use
tty_port. This will allow us to get rid of the need of tty pointer in
many call sites. Only tty_port will be needed and hence no more
tty_port_tty_get calls in those paths.

Here we start with tty_buffer_request_room.

Signed-off-by: Jiri Slaby 
Signed-off-by: Greg Kroah-Hartman

tty: remove use of __devexit

2012-11-21T23:27:46+00:00

CONFIG_HOTPLUG is going away as an option so __devexit is no
longer needed.

Signed-off-by: Bill Pemberton 
Cc: Jiri Slaby 
Cc: Alan Cox 
Acked-by: Tobias Klauser 
Cc: Lucas Tavares 
Cc: Daniel Walker 
Cc: Bryan Huntsman 
Cc: "David S. Miller" 
Cc: Peter Korsgaard 
Cc: Tony Prisk 
Acked-by: David Brown 
Signed-off-by: Greg Kroah-Hartman

tty: remove use of __devinit

2012-11-21T23:22:52+00:00

CONFIG_HOTPLUG is going away as an option so __devinit is no longer
needed.

Signed-off-by: Bill Pemberton 
Cc: Jiri Slaby 
Cc: Alan Cox 
Cc: Lucas Tavares 
Cc: "David S. Miller" 
Cc: Peter Korsgaard 
Cc: Tony Prisk 
Acked-by: Tobias Klauser 
Acked-by: Nicolas Ferre 
Signed-off-by: Greg Kroah-Hartman