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  1. 14 10月, 2010 5 次提交
  3. 13 10月, 2010 5 次提交
    • R
      ARM: relax ioremap prohibition (309caa9c) for -final and -stable · 06c10884
      由 Russell King 提交于 
      ... but produce a big warning about the problem as encouragement
for people to fix their drivers.
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>
      06c10884
    • R
      Merge branch 'for-rmk' of git://git.pengutronix.de/git/imx/linux-2.6 · 841f48a8
      由 Russell King 提交于
      841f48a8
    • M
      ARM: 6440/1: ep93xx: DMA: fix channel_disable · 10d48b39
      由 Mika Westerberg 提交于 
      When channel_disable() is called, it disables per channel interrupts and
waits until channels state becomes STATE_STALL, and then disables the
channel. Now, if the DMA transfer is disabled while the channel is in
STATE_NEXT we will not wait anything and disable the channel immediately.
This seems to cause weird data corruption for example in audio transfers.

Fix is to wait while we are in STATE_NEXT or STATE_ON and only then
disable the channel.
Signed-off-by: NMika Westerberg <mika.westerberg@iki.fi>
Acked-by: NRyan Mallon <ryan@bluewatersys.com>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>
      10d48b39
    • L
      Merge branch 'kvm-updates/2.6.36' of git://git.kernel.org/pub/scm/virt/kvm/kvm · 0acc1b2a
      由 Linus Torvalds 提交于 
      * 'kvm-updates/2.6.36' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
  KVM: x86: Move TSC reset out of vmcb_init
  KVM: x86: Fix SVM VMCB reset
      0acc1b2a
    • S
      ring-buffer: Fix typo of time extends per page · d0134324
      由 Steven Rostedt 提交于 
      Time stamps for the ring buffer are created by the difference between
two events. Each page of the ring buffer holds a full 64 bit timestamp.
Each event has a 27 bit delta stamp from the last event. The unit of time
is nanoseconds, so 27 bits can hold ~134 milliseconds. If two events
happen more than 134 milliseconds apart, a time extend is inserted
to add more bits for the delta. The time extend has 59 bits, which
is good for ~18 years.

Currently the time extend is committed separately from the event.
If an event is discarded before it is committed, due to filtering,
the time extend still exists. If all events are being filtered, then
after ~134 milliseconds a new time extend will be added to the buffer.

This can only happen till the end of the page. Since each page holds
a full timestamp, there is no reason to add a time extend to the
beginning of a page. Time extends can only fill a page that has actual
data at the beginning, so there is no fear that time extends will fill
more than a page without any data.

When reading an event, a loop is made to skip over time extends
since they are only used to maintain the time stamp and are never
given to the caller. As a paranoid check to prevent the loop running
forever, with the knowledge that time extends may only fill a page,
a check is made that tests the iteration of the loop, and if the
iteration is more than the number of time extends that can fit in a page
a warning is printed and the ring buffer is disabled (all of ftrace
is also disabled with it).

There is another event type that is called a TIMESTAMP which can
hold 64 bits of data in the theoretical case that two events happen
18 years apart. This code has not been implemented, but the name
of this event exists, as well as the structure for it. The
size of a TIMESTAMP is 16 bytes, where as a time extend is only
8 bytes. The macro used to calculate how many time extends can fit on
a page used the TIMESTAMP size instead of the time extend size
cutting the amount in half.

The following test case can easily trigger the warning since we only
need to have half the page filled with time extends to trigger the
warning:

 # cd /sys/kernel/debug/tracing/
 # echo function > current_tracer
 # echo 'common_pid < 0' > events/ftrace/function/filter
 # echo > trace
 # echo 1 > trace_marker
 # sleep 120
 # cat trace

Enabling the function tracer and then setting the filter to only trace
functions where the process id is negative (no events), then clearing
the trace buffer to ensure that we have nothing in the buffer,
then write to trace_marker to add an event to the beginning of a page,
sleep for 2 minutes (only 35 seconds is probably needed, but this
guarantees the bug), and then finally reading the trace which will
trigger the bug.

This patch fixes the typo and prevents the false positive of that warning.
Reported-by: NHans J. Koch <hjk@linutronix.de>
Tested-by: NHans J. Koch <hjk@linutronix.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Stable Kernel <stable@kernel.org>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>
      d0134324
  5. 12 10月, 2010 13 次提交
  7. 11 10月, 2010 7 次提交
  9. 10 10月, 2010 10 次提交