Skip to content

L
linux-davinci
Switch branch/tag
  1. 10 Nov, 2009 37 commits
  3. 22 Oct, 2009 3 commits
    • Greg Kroah-Hartman's avatar
      Linux 2.6.31.5 · e2984cbf
      Greg Kroah-Hartman authored 
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
      e2984cbf
    • Linus Torvalds's avatar
      tty: Make flush_to_ldisc() locking more robust · 86d23a05
      Linus Torvalds authored 
      commit c8e33141 upstream.

The locking logic in this function is extremely subtle, and it broke
when we started doing potentially concurrent 'flush_to_ldisc()' calls in
commit e043e42b ("pty: avoid forcing
'low_latency' tty flag").

The code in flush_to_ldisc() used to set 'tty->buf.head' to NULL, with
the intention that this would then cause any other concurrent calls to
not do anything (locking note: we have to drop the buf.lock over the
call to ->receive_buf that can block, which is why we can have
concurrency here at all in the first place).

It also used to set the TTY_FLUSHING bit, which would then cause any
concurrent 'tty_buffer_flush()' to not free all the tty buffers and
clear 'tty->buf.tail'.  And with 'buf.head' being NULL, and 'buf.tail'
being non-NULL, new data would never touch 'buf.head'.

Does that sound a bit too subtle? It was.  If another concurrent call to
'flush_to_ldisc()' were to come in, the NULL buf.head would indeed cause
it to not process the buffer list, but it would still clear TTY_FLUSHING
afterwards, making the buffer protection against 'tty_buffer_flush()' no
longer work.

So this clears it all up.  We depend purely on TTY_FLUSHING for handling
re-entrancy, and stop playing games with the buffer list entirely.  In
fact, the buffer list handling is now robust enough that we could
probably stop doing the whole "protect against 'tty_buffer_flush()'"
thing entirely.

However, Alan also points out that we would probably be better off
simplifying the locking even further, and just take the tty ldisc_mutex
around all the buffer flushing calls.  That seems like a good idea, but
in the meantime this is a conceptually minimal fix (with the patch
itself being bigger than required just to clean the code up and make it
readable).

This fixes keyboard trouble under X:

	http://bugzilla.kernel.org/show_bug.cgi?id=14388Reported-and-tested-by: default avatarFrédéric Meunier <fredlwm@gmail.com>
Reported-and-tested-by: default avatarBoyan <btanastasov@yahoo.co.uk>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Paul Fulghum <paulkf@microgate.com>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
      86d23a05
    • Johannes Berg's avatar
      mac80211: fix vlan and optimise RX · c90aa19d
      Johannes Berg authored 
      commit fbc44bf7 upstream.

When receiving data frames, we can send them only to
the interface they belong to based on transmitting
station (this doesn't work for probe requests). Also,
don't try to handle other frames for AP_VLAN at all
since those interface should only receive data.

Additionally, the transmit side must check that the
station we're sending a frame to is actually on the
interface we're transmitting on, and not transmit
packets to functions that live on other interfaces,
so validate that as well.

Another bug fix is needed in sta_info.c where in the
VLAN case when adding/removing stations we overwrite
the sdata variable we still need.
Signed-off-by: default avatarJohannes Berg <johannes@sipsolutions.net>
Signed-off-by: default avatarJohn W. Linville <linville@tuxdriver.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
      c90aa19d