Skip to content

L
linux-davinci
Switch branch/tag
  1. 18 Nov, 2008 3 commits
    • Johannes Berg's avatar
      iwlagn: fix RX skb alignment · 4018517a
      Johannes Berg authored 
      So I dug deeper into the DMA problems I had with iwlagn and a kind soul
helped me in that he said something about pci-e alignment and mentioned
the iwl_rx_allocate function to check for crossing 4KB boundaries. Since
there's 8KB A-MPDU support, crossing 4k boundaries didn't seem like
something the device would fail with, but when I looked into the
function for a minute anyway I stumbled over this little gem:

	BUG_ON(rxb->dma_addr & (~DMA_BIT_MASK(36) & 0xff));

Clearly, that is a totally bogus check, one would hope the compiler
removes it entirely. (Think about it)

After fixing it, I obviously ran into it, nothing guarantees the
alignment the way you want it,  because of the way skbs and their
headroom are allocated. I won't explain that here nor double-check that
I'm right, that goes beyond what most of the CC'ed people care about.

So then I came up with the patch below, and so far my system has
survived minutes with 64K pages, when it would previously fail in
seconds. And I haven't seen a single instance of the TX bug either. But
when you see the patch it'll be pretty obvious to you why.

This should fix the following reported kernel bugs:

http://bugzilla.kernel.org/show_bug.cgi?id=11596
http://bugzilla.kernel.org/show_bug.cgi?id=11393
http://bugzilla.kernel.org/show_bug.cgi?id=11983

I haven't checked if there are any elsewhere, but I suppose RHBZ will
have a few instances too...

I'd like to ask anyone who is CC'ed (those are people I know ran into
the bug) to try this patch.

I am convinced that this patch is correct in spirit, but I haven't
understood why, for example, there are so many unmap calls. I'm not
entirely convinced that this is the only bug leading to the TX reply
errors.
Signed-off-by: default avatarJohannes Berg <johannes@sipsolutions.net>
Signed-off-by: default avatarJohn W. Linville <linville@tuxdriver.com>
      4018517a
    • Johannes Berg's avatar
      mac80211: remove ieee80211_notify_mac · 8e3bad65
      Johannes Berg authored 
      Before ieee80211_notify_mac() was added, it was presented with the
use case of using it to tell mac80211 that the association may
have been lost because the firmware crashed/reset.

Since then, it has also been used by iwlwifi to (slightly) speed
up re-association after resume, a workaround around the fact that
mac80211 has no suspend/resume handling yet. It is also not used
by any other drivers, so clearly it cannot be necessary for "good
enough" suspend/resume.

Unfortunately, the callback suffers from a severe problem: It only
works for station mode. If suspend/resume happens while in IBSS or
any other mode (but station), then the callback is pointless.

Recently, it has created a number of locking issues, first because
it required rtnl locking rather than RCU due to calling sleeping
functions within the critical section, and now because it's called
by iwlwifi from the mac80211 workqueue that may not use the rtnl
because it is flushed under rtnl.
(cf. http://bugzilla.kernel.org/show_bug.cgi?id=12046)

I think, therefore, that we should take a step back, remove it
entirely for now and add the small feature it provided properly.
For suspend and resume we will need to introduce new hooks, and for
the case where the firmware was reset the driver will probably
simply just pretend it has done a suspend/resume cycle to get
mac80211 to reprogram the hardware completely, not just try to
connect to the current AP again in station mode. When doing so, we
will need to take into account locking issues and possibly defer
to schedule_work from within mac80211 for the resume operation,
while the suspend operation must be done directly.

Proper suspend/resume should also not necessarily try to reconnect
to the current AP, the time spent in suspend may have been short
enough to not be disconnected from the AP, mac80211 will detect
that the AP went out of range quickly if it did, and if the
association is lost then the AP will disassoc as soon as a data
frame is sent. We might also take into account WWOL then, and
have mac80211 program the hardware into such a mode where it is
available and requested.
Signed-off-by: default avatarJohannes Berg <johannes@sipsolutions.net>
Signed-off-by: default avatarJohn W. Linville <linville@tuxdriver.com>
      8e3bad65
    • Johannes Berg's avatar
      libertas_tf: fix skb tail pointer · 9b44fb89
      Johannes Berg authored 
      skb->tail can't be meant here because it's not the same across 32/64 bit
compilations. This means there's no way the current driver can work on
64-bit architectures.
Signed-off-by: default avatarJohannes Berg <johannes@sipsolutions.net>
Cc: stable@kernel.org [2.6.27]
Signed-off-by: default avatarJohn W. Linville <linville@tuxdriver.com>
      9b44fb89
  3. 17 Nov, 2008 5 commits
  5. 16 Nov, 2008 8 commits
  7. 15 Nov, 2008 2 commits
  9. 14 Nov, 2008 10 commits
  11. 13 Nov, 2008 4 commits
  13. 12 Nov, 2008 8 commits