linux-toradex.git/init, branch v2.6.39-rc5

init/Kconfig: fix EXPERT menu list

2011-04-27T03:48:37+00:00

The EXPERT menu list was recently broken by the insertion of a
kconfig symbol (EMBEDDED) at the beginning of the EXPERT list of
kconfig items.  Broken by:

  commit 6a108a14fa356ef607be308b68337939e56ea94e
  Author: David Rientjes 
  Date:   Thu Jan 20 14:44:16 2011 -0800
    kconfig: rename CONFIG_EMBEDDED to CONFIG_EXPERT

Restore the EXPERT menu list -- don't inject a symbol (EMBEDDED)
that does not depend on EXPERT into the list.

Signed-off-by: Randy Dunlap 
Cc: David Rientjes 
Cc: Peter Foley 
Signed-off-by: Linus Torvalds

Fix common misspellings

2011-03-31T14:26:23+00:00

Fixes generated by 'codespell' and manually reviewed.

Signed-off-by: Lucas De Marchi

userns: add a user_namespace as creator/owner of uts_namespace

2011-03-24T02:46:59+00:00

The expected course of development for user namespaces targeted
capabilities is laid out at https://wiki.ubuntu.com/UserNamespace.

Goals:

- Make it safe for an unprivileged user to unshare namespaces.  They
  will be privileged with respect to the new namespace, but this should
  only include resources which the unprivileged user already owns.

- Provide separate limits and accounting for userids in different
  namespaces.

Status:

  Currently (as of 2.6.38) you can clone with the CLONE_NEWUSER flag to
  get a new user namespace if you have the CAP_SYS_ADMIN, CAP_SETUID, and
  CAP_SETGID capabilities.  What this gets you is a whole new set of
  userids, meaning that user 500 will have a different 'struct user' in
  your namespace than in other namespaces.  So any accounting information
  stored in struct user will be unique to your namespace.

  However, throughout the kernel there are checks which

  - simply check for a capability.  Since root in a child namespace
    has all capabilities, this means that a child namespace is not
    constrained.

  - simply compare uid1 == uid2.  Since these are the integer uids,
    uid 500 in namespace 1 will be said to be equal to uid 500 in
    namespace 2.

  As a result, the lxc implementation at lxc.sf.net does not use user
  namespaces.  This is actually helpful because it leaves us free to
  develop user namespaces in such a way that, for some time, user
  namespaces may be unuseful.

Bugs aside, this patchset is supposed to not at all affect systems which
are not actively using user namespaces, and only restrict what tasks in
child user namespace can do.  They begin to limit privilege to a user
namespace, so that root in a container cannot kill or ptrace tasks in the
parent user namespace, and can only get world access rights to files.
Since all files currently belong to the initila user namespace, that means
that child user namespaces can only get world access rights to *all*
files.  While this temporarily makes user namespaces bad for system
containers, it starts to get useful for some sandboxing.

I've run the 'runltplite.sh' with and without this patchset and found no
difference.

This patch:

copy_process() handles CLONE_NEWUSER before the rest of the namespaces.
So in the case of clone(CLONE_NEWUSER|CLONE_NEWUTS) the new uts namespace
will have the new user namespace as its owner.  That is what we want,
since we want root in that new userns to be able to have privilege over
it.

Changelog:
	Feb 15: don't set uts_ns->user_ns if we didn't create
		a new uts_ns.
	Feb 23: Move extern init_user_ns declaration from
		init/version.c to utsname.h.

Signed-off-by: Serge E. Hallyn 
Acked-by: "Eric W. Biederman" 
Acked-by: Daniel Lezcano 
Acked-by: David Howells 
Cc: James Morris 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

pid: remove the child_reaper special case in init/main.c

2011-03-24T02:46:57+00:00

This patchset is a cleanup and a preparation to unshare the pid namespace.
These prerequisites prepare for Eric's patchset to give a file descriptor
to a namespace and join an existing namespace.

This patch:

It turns out that the existing assignment in copy_process of the
child_reaper can handle the initial assignment of child_reaper we just
need to generalize the test in kernel/fork.c

Signed-off-by: Eric W. Biederman 
Signed-off-by: Daniel Lezcano 
Cc: Oleg Nesterov 
Cc: Alexey Dobriyan 
Acked-by: Serge E. Hallyn 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

init: return proper error code in do_mounts_rd()

2011-03-23T00:44:15+00:00

In do_mounts_rd() if memory cannot be allocated, return -ENOMEM.

Signed-off-by: Davidlohr Bueso 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

calibrate: retry with wider bounds when converge seems to fail

2011-03-23T00:44:12+00:00

Systems with unmaskable interrupts such as SMIs may massively
underestimate loops_per_jiffy, and fail to converge anywhere near the real
value.  A case seen on x86_64 was an initial estimate of 256<<12, which
converged to 511<<12 where the real value should have been over 630<<12.
This admitedly requires bypassing the TSC calibration (lpj_fine), and a
failure to settle in the direct calibration too, but is physically
possible.  This failure does not depend on my previous calibration
optimisation, but by luck is easy to fix with the optimisation in place
with a trivial retry loop.

In the context of the optimised converging method, as we can no longer
trust the starting estimate, enlarge the search bounds exponentially so
that the number of retries is logarithmically bounded.

[akpm@linux-foundation.org: mention x86_64 SMIs in comment]
Signed-off-by: Phil Carmody 
Cc: Ingo Molnar 
Cc: Thomas Gleixner 
Cc: "H. Peter Anvin" 
Tested-by: Stephen Boyd 
Cc: Greg KH 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

calibrate: home in on correct lpj value more quickly

2011-03-23T00:44:11+00:00

Binary chop with a jiffy-resync on each step to find an upper bound is
slow, so just race in a tight-ish loop to find an underestimate.

If done with lots of individual steps, sometimes several hundreds of
iterations would be required, which would impose a significant overhead,
and make the initial estimate very low.  By taking slowly increasing steps
there will be less overhead.

E.g.  an x86_64 2.67GHz could have fitted in 613 individual small delays,
but in reality should have been able to fit in a single delay 644 times
longer, so underestimated by 31 steps.  To reach the equivalent of 644
small delays with the accelerating scheme now requires about 130
iterations, so has <1/4th of the overhead, and can therefore be expected
to underestimate by only 7 steps.

As now we have a better initial estimate we can binary chop over a smaller
range.  With the loop overhead in the initial estimate kept low, and the
step sizes moderate, we won't have under-estimated by much, so chose as
tight a range as we can.

Signed-off-by: Phil Carmody 
Cc: Ingo Molnar 
Cc: Thomas Gleixner 
Cc: "H. Peter Anvin" 
Tested-by: Stephen Boyd 
Cc: Greg KH 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

calibrate: extract fall-back calculation into own helper

2011-03-23T00:44:11+00:00

The motivation for this patch series is that currently our OMAP calibrates
itself using the trial-and-error binary chop fallback that some other
architectures no longer need to perform.  This is a lengthy process,
taking 0.2s in an environment where boot time is of great interest.

Patch 2/4 has two optimisations.  Firstly, it replaces the initial
repeated- doubling to find the relevant power of 2 with a tight loop that
just does as much as it can in a jiffy.  Secondly, it doesn't binary chop
over an entire power of 2 range, it choses a much smaller range based on
how much it squeezed in, and failed to squeeze in, during the first stage.
 Both are significant optimisations, and bring our calibration down from
23 jiffies to 5, and, in the process, often arrive at a more accurate lpj
value.

The 'bands' and 'sub-logarithmic' growth may look over-engineered, but
they only cost a small level of inaccuracy in the initial guess (for all
architectures) in order to avoid the very large inaccuracies that appeared
during testing (on x86_64 architectures, and presumably others with less
metronomic operation).  Note that due to the existence of the TSC and
other timers, the x86_64 will not typically use this fallback routine, but
I wanted to code defensively, able to cope with all kinds of processor
behaviours and kernel command line options.

Patch 3/4 is an additional trap for the nightmare scenario where the
initial estimate is very inaccurate, possibly due to things like SMIs.
It simply retries with a larger bound.

Stephen said:

I tried this patch set out on an MSM7630.
:
: Before:
:
: Calibrating delay loop... 681.57 BogoMIPS (lpj=3407872)
:
: After:
:
: Calibrating delay loop... 680.75 BogoMIPS (lpj=3403776)
:
: But the really good news is calibration time dropped from ~247ms to ~56ms.
:  Sadly we won't be able to benefit from this should my udelay patches make
: it into ARM because we would be using calibrate_delay_direct() instead (at
: least on machines who choose to).  Can we somehow reapply the logic behind
: this to calibrate_delay_direct()?  That would be even better, but this is
: definitely a boot time improvement.
:
: Or maybe we could just replace calibrate_delay_direct() with this fallback
: calculation?  If __delay() is a thin wrapper around read_current_timer()
: it should work just as well (plus patch 3 makes it handle SMIs).  I'll try
: that out.

This patch:

... so that it can be modified more clinically.

This is almost entirely cosmetic. The only change to the operation
is that the global variable is only set once after the estimation is
completed, rather than taking on all the intermediate values. However,
there are no readers of that variable, so this change is unimportant.

Signed-off-by: Phil Carmody 
Cc: Ingo Molnar 
Cc: Thomas Gleixner 
Cc: "H. Peter Anvin" 
Tested-by: Stephen Boyd 
Cc: Greg KH 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

smp: move smp setup functions to kernel/smp.c

2011-03-23T00:44:11+00:00

Move setup_nr_cpu_ids(), smp_init() and some other SMP boot parameter
setup functions from init/main.c to kenrel/smp.c, saves some #ifdef
CONFIG_SMP.

Signed-off-by: WANG Cong 
Cc: Rakib Mullick 
Cc: David Howells 
Cc: Ingo Molnar 
Cc: Peter Zijlstra 
Cc: Tejun Heo 
Cc: Arnd Bergmann 
Cc: Akinobu Mita 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

fs: use appropriate printk priority levels

2011-03-23T00:44:10+00:00

printk()s without a priority level default to KERN_WARNING.  To reduce
noise at KERN_WARNING, this patch set the priority level appriopriately
for unleveled printks()s.  This should be useful to folks that look at
dmesg warnings closely.

Signed-off-by: Mandeep Singh Baines 
Cc: Jens Axboe 
Cc: Al Viro 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds