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  1. 08 Feb, 2009 3 commits
  3. 03 Feb, 2009 12 commits
  5. 02 Feb, 2009 23 commits
  7. 01 Feb, 2009 2 commits
    • Linus Torvalds's avatar
      Manually revert "mlock: downgrade mmap sem while populating mlocked regions" · 27421e21
      Linus Torvalds authored 
      This essentially reverts commit 8edb08ca.

It downgraded our mmap semaphore to a read-lock while mlocking pages, in
order to allow other threads (and external accesses like "ps" et al) to
walk the vma lists and take page faults etc.  Which is a nice idea, but
the implementation does not work.

Because we cannot upgrade the lock back to a write lock without
releasing the mmap semaphore, the code had to release the lock entirely
and then re-take it as a writelock.  However, that meant that the caller
possibly lost the vma chain that it was following, since now another
thread could come in and mmap/munmap the range.

The code tried to work around that by just looking up the vma again and
erroring out if that happened, but quite frankly, that was just a buggy
hack that doesn't actually protect against anything (the other thread
could just have replaced the vma with another one instead of totally
unmapping it).

The only way to downgrade to a read map _reliably_ is to do it at the
end, which is likely the right thing to do: do all the 'vma' operations
with the write-lock held, then downgrade to a read after completing them
all, and then do the "populate the newly mlocked regions" while holding
just the read lock.  And then just drop the read-lock and return to user
space.

The (perhaps somewhat simpler) alternative is to just make all the
callers of mlock_vma_pages_range() know that the mmap lock got dropped,
and just re-grab the mmap semaphore if it needs to mlock more than one
vma region.

So we can do this "downgrade mmap sem while populating mlocked regions"
thing right, but the way it was done here was absolutely not correct.
Thus the revert, in the expectation that we will do it all correctly
some day.

Cc: Lee Schermerhorn <lee.schermerhorn@hp.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: stable@kernel.org
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      27421e21
    • Devin Heitmueller's avatar
      V4L/DVB (10411): s5h1409: Perform s5h1409 soft reset after tuning · 67e70baf
      Devin Heitmueller authored 
      Just like with the s5h1411, the s5h1409 needs a soft-reset in order for it
to know that the tuner has been told to change frequencies.  This change
changes the behavior from "random tuning times between 500ms to complete
tuning lock failures" to "tuning lock consistently within 700ms".

Thanks to Robert Krakora <rob.krakora@messagenetsystems.com> for doing
initial testing of the patch on the KWorld 330U.

Thanks to Andy Walls <awalls@radix.net> for doing testing of the patch on
the HVR-1600.

Thanks to Michael Krufky <mkrufky@linuxtv.org> for doing additional testing.
Signed-off-by: default avatarDevin Heitmueller <dheitmueller@linuxtv.org>
Signed-off-by: default avatarMichael Krufky <mkrufky@linuxtv.org>
Signed-off-by: default avatarMauro Carvalho Chehab <mchehab@redhat.com>
      67e70baf
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