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  1. 09 May, 2012 5 commits
  3. 07 May, 2012 7 commits
  5. 01 May, 2012 23 commits
  7. 29 Apr, 2012 5 commits
    • Linus Torvalds's avatar
      Linux 3.4-rc5 · 69964ea4
      Linus Torvalds authored
      69964ea4
    • Linus Torvalds's avatar
      Merge tag 'pm-for-3.4-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm · 6cfdd02b
      Linus Torvalds authored 
      Pull power management fixes from Rafael J. Wysocki:
 "Fix for an issue causing hibernation to hang on systems with highmem
  (that practically means i386) due to broken memory management (bug
  introduced in 3.2, so -stable material) and PM documentation update
  making the freezer documentation follow the code again after some
  recent updates."

* tag 'pm-for-3.4-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
  PM / Freezer / Docs: Update documentation about freezing of tasks
  PM / Hibernate: fix the number of pages used for hibernate/thaw buffering
      6cfdd02b
    • Linus Torvalds's avatar
      autofs: make the autofsv5 packet file descriptor use a packetized pipe · 64f371bc
      Linus Torvalds authored 
      The autofs packet size has had a very unfortunate size problem on x86:
because the alignment of 'u64' differs in 32-bit and 64-bit modes, and
because the packet data was not 8-byte aligned, the size of the autofsv5
packet structure differed between 32-bit and 64-bit modes despite
looking otherwise identical (300 vs 304 bytes respectively).

We first fixed that up by making the 64-bit compat mode know about this
problem in commit a32744d4 ("autofs: work around unhappy compat
problem on x86-64"), and that made a 32-bit 'systemd' work happily on a
64-bit kernel because everything then worked the same way as on a 32-bit
kernel.

But it turned out that 'automount' had actually known and worked around
this problem in user space, so fixing the kernel to do the proper 32-bit
compatibility handling actually *broke* 32-bit automount on a 64-bit
kernel, because it knew that the packet sizes were wrong and expected
those incorrect sizes.

As a result, we ended up reverting that compatibility mode fix, and
thus breaking systemd again, in commit fcbf94b9.

With both automount and systemd doing a single read() system call, and
verifying that they get *exactly* the size they expect but using
different sizes, it seemed that fixing one of them inevitably seemed to
break the other.  At one point, a patch I seriously considered applying
from Michael Tokarev did a "strcmp()" to see if it was automount that
was doing the operation.  Ugly, ugly.

However, a prettier solution exists now thanks to the packetized pipe
mode.  By marking the communication pipe as being packetized (by simply
setting the O_DIRECT flag), we can always just write the bigger packet
size, and if user-space does a smaller read, it will just get that
partial end result and the extra alignment padding will simply be thrown
away.

This makes both automount and systemd happy, since they now get the size
they asked for, and the kernel side of autofs simply no longer needs to
care - it could pad out the packet arbitrarily.

Of course, if there is some *other* user of autofs (please, please,
please tell me it ain't so - and we haven't heard of any) that tries to
read the packets with multiple writes, that other user will now be
broken - the whole point of the packetized mode is that one system call
gets exactly one packet, and you cannot read a packet in pieces.
Tested-by: default avatarMichael Tokarev <mjt@tls.msk.ru>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: David Miller <davem@davemloft.net>
Cc: Ian Kent <raven@themaw.net>
Cc: Thomas Meyer <thomas@m3y3r.de>
Cc: stable@kernel.org
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      64f371bc
    • Marcos Paulo de Souza's avatar
      PM / Freezer / Docs: Update documentation about freezing of tasks · 26e0f90f
      Marcos Paulo de Souza authored 
      The file Documentation/power/freezing-of-tasks.txt was still referencing
the TIF_FREEZE flag, that was removed by the commit
d88e4cb6(freezer: remove now unused
TIF_FREEZE).

This patch removes all the references of TIF_FREEZE that were left
behind.
Signed-off-by: default avatarMarcos Paulo de Souza <marcos.souza.org@gmail.com>
Signed-off-by: default avatarSrivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Signed-off-by: default avatarRafael J. Wysocki <rjw@sisk.pl>
      26e0f90f
    • Linus Torvalds's avatar
      pipes: add a "packetized pipe" mode for writing · 9883035a
      Linus Torvalds authored 
      The actual internal pipe implementation is already really about
individual packets (called "pipe buffers"), and this simply exposes that
as a special packetized mode.

When we are in the packetized mode (marked by O_DIRECT as suggested by
Alan Cox), a write() on a pipe will not merge the new data with previous
writes, so each write will get a pipe buffer of its own.  The pipe
buffer is then marked with the PIPE_BUF_FLAG_PACKET flag, which in turn
will tell the reader side to break the read at that boundary (and throw
away any partial packet contents that do not fit in the read buffer).

End result: as long as you do writes less than PIPE_BUF in size (so that
the pipe doesn't have to split them up), you can now treat the pipe as a
packet interface, where each read() system call will read one packet at
a time.  You can just use a sufficiently big read buffer (PIPE_BUF is
sufficient, since bigger than that doesn't guarantee atomicity anyway),
and the return value of the read() will naturally give you the size of
the packet.

NOTE! We do not support zero-sized packets, and zero-sized reads and
writes to a pipe continue to be no-ops.  Also note that big packets will
currently be split at write time, but that the size at which that
happens is not really specified (except that it's bigger than PIPE_BUF).
Currently that limit is the system page size, but we might want to
explicitly support bigger packets some day.

The main user for this is going to be the autofs packet interface,
allowing us to stop having to care so deeply about exact packet sizes
(which have had bugs with 32/64-bit compatibility modes).  But user
space can create packetized pipes with "pipe2(fd, O_DIRECT)", which will
fail with an EINVAL on kernels that do not support this interface.
Tested-by: default avatarMichael Tokarev <mjt@tls.msk.ru>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: David Miller <davem@davemloft.net>
Cc: Ian Kent <raven@themaw.net>
Cc: Thomas Meyer <thomas@m3y3r.de>
Cc: stable@kernel.org  # needed for systemd/autofs interaction fix
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      9883035a
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