linux-toradex.git, branch v3.16.5

Linux 3.16.5

2014-10-09T19:24:04+00:00

jiffies: Fix timeval conversion to jiffies

2014-10-09T19:23:49+00:00

commit d78c9300c51d6ceed9f6d078d4e9366f259de28c upstream.

timeval_to_jiffies tried to round a timeval up to an integral number
of jiffies, but the logic for doing so was incorrect: intervals
corresponding to exactly N jiffies would become N+1. This manifested
itself particularly repeatedly stopping/starting an itimer:

setitimer(ITIMER_PROF, &val, NULL);
setitimer(ITIMER_PROF, NULL, &val);

would add a full tick to val, _even if it was exactly representable in
terms of jiffies_ (say, the result of a previous rounding.)  Doing
this repeatedly would cause unbounded growth in val.  So fix the math.

Here's what was wrong with the conversion: we essentially computed
(eliding seconds)

jiffies = usec  * (NSEC_PER_USEC/TICK_NSEC)

by using scaling arithmetic, which took the best approximation of
NSEC_PER_USEC/TICK_NSEC with denominator of 2^USEC_JIFFIE_SC =
x/(2^USEC_JIFFIE_SC), and computed:

jiffies = (usec * x) >> USEC_JIFFIE_SC

and rounded this calculation up in the intermediate form (since we
can't necessarily exactly represent TICK_NSEC in usec.) But the
scaling arithmetic is a (very slight) *over*approximation of the true
value; that is, instead of dividing by (1 usec/ 1 jiffie), we
effectively divided by (1 usec/1 jiffie)-epsilon (rounding
down). This would normally be fine, but we want to round timeouts up,
and we did so by adding 2^USEC_JIFFIE_SC - 1 before the shift; this
would be fine if our division was exact, but dividing this by the
slightly smaller factor was equivalent to adding just _over_ 1 to the
final result (instead of just _under_ 1, as desired.)

In particular, with HZ=1000, we consistently computed that 10000 usec
was 11 jiffies; the same was true for any exact multiple of
TICK_NSEC.

We could possibly still round in the intermediate form, adding
something less than 2^USEC_JIFFIE_SC - 1, but easier still is to
convert usec->nsec, round in nanoseconds, and then convert using
time*spec*_to_jiffies.  This adds one constant multiplication, and is
not observably slower in microbenchmarks on recent x86 hardware.

Tested: the following program:

int main() {
  struct itimerval zero = {{0, 0}, {0, 0}};
  /* Initially set to 10 ms. */
  struct itimerval initial = zero;
  initial.it_interval.tv_usec = 10000;
  setitimer(ITIMER_PROF, &initial, NULL);
  /* Save and restore several times. */
  for (size_t i = 0; i < 10; ++i) {
    struct itimerval prev;
    setitimer(ITIMER_PROF, &zero, &prev);
    /* on old kernels, this goes up by TICK_USEC every iteration */
    printf("previous value: %ld %ld %ld %ld\n",
           prev.it_interval.tv_sec, prev.it_interval.tv_usec,
           prev.it_value.tv_sec, prev.it_value.tv_usec);
    setitimer(ITIMER_PROF, &prev, NULL);
  }
    return 0;
}


Cc: Thomas Gleixner 
Cc: Ingo Molnar 
Cc: Paul Turner 
Cc: Richard Cochran 
Cc: Prarit Bhargava 
Reviewed-by: Paul Turner 
Reported-by: Aaron Jacobs 
Signed-off-by: Andrew Hunter 
[jstultz: Tweaked to apply to 3.17-rc]
Signed-off-by: John Stultz 
[bwh: Backported to 3.16: adjust filename]
Signed-off-by: Ben Hutchings 
Signed-off-by: Greg Kroah-Hartman

media: vb2: fix VBI/poll regression

2014-10-09T19:23:49+00:00

commit 58d75f4b1ce26324b4d809b18f94819843a98731 upstream.

The recent conversion of saa7134 to vb2 unconvered a poll() bug that
broke the teletext applications alevt and mtt. These applications
expect that calling poll() without having called VIDIOC_STREAMON will
cause poll() to return POLLERR. That did not happen in vb2.

This patch fixes that behavior. It also fixes what should happen when
poll() is called when STREAMON is called but no buffers have been
queued. In that case poll() will also return POLLERR, but only for
capture queues since output queues will always return POLLOUT
anyway in that situation.

This brings the vb2 behavior in line with the old videobuf behavior.

Signed-off-by: Hans Verkuil 
Acked-by: Laurent Pinchart 
Signed-off-by: Mauro Carvalho Chehab 
Signed-off-by: Greg Kroah-Hartman

mm: numa: Do not mark PTEs pte_numa when splitting huge pages

2014-10-09T19:23:49+00:00

commit abc40bd2eeb77eb7c2effcaf63154aad929a1d5f upstream.

This patch reverts 1ba6e0b50b ("mm: numa: split_huge_page: transfer the
NUMA type from the pmd to the pte"). If a huge page is being split due
a protection change and the tail will be in a PROT_NONE vma then NUMA
hinting PTEs are temporarily created in the protected VMA.

 VM_RW|VM_PROTNONE
|-----------------|
      ^
      split here

In the specific case above, it should get fixed up by change_pte_range()
but there is a window of opportunity for weirdness to happen. Similarly,
if a huge page is shrunk and split during a protection update but before
pmd_numa is cleared then a pte_numa can be left behind.

Instead of adding complexity trying to deal with the case, this patch
will not mark PTEs NUMA when splitting a huge page. NUMA hinting faults
will not be triggered which is marginal in comparison to the complexity
in dealing with the corner cases during THP split.

Signed-off-by: Mel Gorman 
Acked-by: Rik van Riel 
Acked-by: Kirill A. Shutemov 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

mm, thp: move invariant bug check out of loop in __split_huge_page_map

2014-10-09T19:23:49+00:00

commit f8303c2582b889351e261ff18c4d8eb197a77db2 upstream.

In __split_huge_page_map(), the check for page_mapcount(page) is
invariant within the for loop.  Because of the fact that the macro is
implemented using atomic_read(), the redundant check cannot be optimized
away by the compiler leading to unnecessary read to the page structure.

This patch moves the invariant bug check out of the loop so that it will
be done only once.  On a 3.16-rc1 based kernel, the execution time of a
microbenchmark that broke up 1000 transparent huge pages using munmap()
had an execution time of 38,245us and 38,548us with and without the
patch respectively.  The performance gain is about 1%.

Signed-off-by: Waiman Long 
Acked-by: Kirill A. Shutemov 
Cc: Andrea Arcangeli 
Cc: Mel Gorman 
Cc: Rik van Riel 
Cc: Scott J Norton 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

vgaarb: Don't default exclusively to first video device with mem+io

2014-10-09T19:23:49+00:00

commit 86fd887b7fe350819dae5b55e7fef05b511c8656 upstream.

Commit 20cde694027e ("x86, ia64: Move EFI_FB vga_default_device()
initialization to pci_vga_fixup()") moved boot video device detection from
efifb to x86 and ia64 pci/fixup.c.

For dual-GPU Apple computers above change represents a regression as code
in efifb did forcefully override vga_default_device while the merge did not
(vgaarb happens prior to PCI fixup).

To improve on initial device selection by vgaarb (it cannot know if PCI
device not behind bridges see/decode legacy VGA I/O or not), move the
screen_info based check from pci_video_fixup() to vgaarb's init function and
use it to refine/override decision taken while adding the individual PCI
VGA devices.  This way PCI fixup has no reason to adjust vga_default_device
anymore but can depend on its value for flagging shadowed VBIOS.

This has the nice benefit of removing duplicated code but does introduce a
#if defined() block in vgaarb.  Not all architectures have screen_info and
would cause compile to fail without it.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=84461
Reported-and-Tested-By: Andreas Noever 
Signed-off-by: Bruno Prémont 
Signed-off-by: Bjorn Helgaas 
CC: Matthew Garrett 
Signed-off-by: Greg Kroah-Hartman

x86, ia64: Move EFI_FB vga_default_device() initialization to pci_vga_fixup()

2014-10-09T19:23:49+00:00

commit 20cde694027e7477cc532833e38ab9fcaa83fb64 upstream.

Commit b4aa0163056b ("efifb: Implement vga_default_device() (v2)") added
efifb vga_default_device() so EFI systems that do not load shadow VBIOS or
setup VGA get proper value for boot_vga PCI sysfs attribute on the
corresponding PCI device.

Xorg doesn't detect devices when boot_vga=0, e.g., on some EFI systems such
as MacBookAir2,1.  Xorg detects the GPU and finds the DRI device but then
bails out with "no devices detected".

Note: When vga_default_device() is set boot_vga PCI sysfs attribute
reflects its state.  When unset this attribute is 1 whenever
IORESOURCE_ROM_SHADOW flag is set.

With introduction of sysfb/simplefb/simpledrm efifb is getting obsolete
while having native drivers for the GPU also makes selecting sysfb/efifb
optional.

Remove the efifb implementation of vga_default_device() and initialize
vgaarb's vga_default_device() with the PCI GPU that matches boot
screen_info in pci_fixup_video().

[bhelgaas: remove unused "dev" in efifb_setup()]
Fixes: b4aa0163056b ("efifb: Implement vga_default_device() (v2)")
Tested-by: Anibal Francisco Martinez Cortina 
Signed-off-by: Bruno Prémont 
Signed-off-by: Bjorn Helgaas 
Acked-by: Matthew Garrett 
Signed-off-by: Greg Kroah-Hartman

uas: Add missing le16_to_cpu calls to asm1051 / asm1053 usb-id check

2014-10-09T19:23:49+00:00

commit a79e5bc53a9519202dfad7d916761601fcbf8db1 upstream.

Reported-by: kbuild test robot 
Signed-off-by: Hans de Goede 
Signed-off-by: Greg Kroah-Hartman

uas: Disable uas on ASM1051 devices

2014-10-09T19:23:49+00:00

commit a9c54caa456dccba938005f6479892b589975e6a upstream.

There are a large numbers of issues with ASM1051 devices in uas mode:

1) They do not support REPORT SUPPORTED OPERATION CODES

2) They use out of spec 8 byte status iu-s when they have no sense data,
   switching to normal 16 byte status iu-s when they do have sense data.

3) They hang / crash when combined with some disks, e.g. a Crucial M500 ssd.

4) They hang / crash when stressed (through e.g. sg_reset --bus) with disks
   with which then normally do work (once 1 & 2 are worked around).

Where as in BOT mode they appear to work fine, so the best way forward with
these devices is to just blacklist them for uas usage.

Unfortunately this is easier said then done. as older versions of the ASM1053
(which works fine) use the same usb-id as the ASM1051.

When connected over USB-3 the 2 can be told apart by the number of streams
they support. So this patch adds some less then pretty code to disable uas for
the ASM1051. When connected over USB-2, simply disable uas alltogether for
devices with the shared usb-id.

Cc: stable@vger.kernel.org # 3.16
Signed-off-by: Hans de Goede 
Signed-off-by: Greg Kroah-Hartman

uas: Log a warning when we cannot use uas because the hcd lacks streams

2014-10-09T19:23:49+00:00

commit 43508be512661c905d0320ee73e0b65ef36d2459 upstream.

So that an user who wants to use uas can see why he is not getting uas.

Also move the check down so that we don't warn if there are other reasons
why uas cannot work.

Signed-off-by: Hans de Goede 
Signed-off-by: Greg Kroah-Hartman