Li Zefan [Wed, 25 Mar 2009 09:21:26 +0000 (17:21 +0800)]
blktrace: fix the original blktrace
Currently the original blktrace, which is using relay and is used via
ioctl, is broken. You can use ftrace to see the output of blktrace,
but user-space blktrace is unusable.
Also:
- make act_mask accept "ahead", "meta", "discard" and "drv_data"
- use strsep() instead of strchr() to parse user input
- return -EINVAL if a token is not found in the mask map
- fix a bug that 'value' is unsigned, so it can < 0
- propagate error value of blk_trace_mask2str() to userspace, but not
always return -ENXIO.
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com> Acked-by: Jens Axboe <jens.axboe@oracle.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
LKML-Reference: <49C8AB42.1000802@cn.fujitsu.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Jeff Moyer [Thu, 19 Mar 2009 00:04:21 +0000 (17:04 -0700)]
aio: lookup_ioctx can return the wrong value when looking up a bogus context
The libaio test harness turned up a problem whereby lookup_ioctx on a
bogus io context was returning the 1 valid io context from the list
(harness/cases/3.p).
Because of that, an extra put_iocontext was done, and when the process
exited, it hit a BUG_ON in the put_iocontext macro called from exit_aio
(since we expect a users count of 1 and instead get 0).
Thanks to Zach for pointing out that hlist_for_each_entry_rcu will not
return with a NULL tpos at the end of the loop, even if the entry was
not found.
Signed-off-by: Jeff Moyer <jmoyer@redhat.com> Acked-by: Zach Brown <zach.brown@oracle.com> Acked-by: Jens Axboe <jens.axboe@oracle.com> Cc: Benjamin LaHaise <bcrl@kvack.org> Cc: <stable@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Davide Libenzi [Thu, 19 Mar 2009 00:04:19 +0000 (17:04 -0700)]
eventfd: remove fput() call from possible IRQ context
Remove a source of fput() call from inside IRQ context. Myself, like Eric,
wasn't able to reproduce an fput() call from IRQ context, but Jeff said he was
able to, with the attached test program. Independently from this, the bug is
conceptually there, so we might be better off fixing it. This patch adds an
optimization similar to the one we already do on ->ki_filp, on ->ki_eventfd.
Playing with ->f_count directly is not pretty in general, but the alternative
here would be to add a brand new delayed fput() infrastructure, that I'm not
sure is worth it.
Signed-off-by: Davide Libenzi <davidel@xmailserver.org> Cc: Benjamin LaHaise <bcrl@kvack.org> Cc: Trond Myklebust <trond.myklebust@fys.uio.no> Cc: Eric Dumazet <dada1@cosmosbay.com> Signed-off-by: Jeff Moyer <jmoyer@redhat.com> Cc: Zach Brown <zach.brown@oracle.com> Cc: <stable@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Linus Torvalds [Thu, 19 Mar 2009 21:56:35 +0000 (14:56 -0700)]
Merge branch 'for-linus' of git://git390.marist.edu/pub/scm/linux-2.6
* 'for-linus' of git://git390.marist.edu/pub/scm/linux-2.6:
[S390] make page table upgrade work again
[S390] make page table walking more robust
[S390] Dont check for pfn_valid() in uaccess_pt.c
[S390] ftrace/mcount: fix kernel stack backchain
[S390] topology: define SD_MC_INIT to fix performance regression
[S390] __div64_31 broken for CONFIG_MARCH_G5
* git://git.kernel.org/pub/scm/linux/kernel/git/mason/btrfs-unstable:
Btrfs: Clear space_info full when adding new devices
Btrfs: Fix locking around adding new space_info
Linus Torvalds [Thu, 19 Mar 2009 18:32:05 +0000 (11:32 -0700)]
Fix race in create_empty_buffers() vs __set_page_dirty_buffers()
Nick Piggin noticed this (very unlikely) race between setting a page
dirty and creating the buffers for it - we need to hold the mapping
private_lock until we've set the page dirty bit in order to make sure
that create_empty_buffers() might not build up a set of buffers without
the dirty bits set when the page is dirty.
I doubt anybody has ever hit this race (and it didn't solve the issue
Nick was looking at), but as Nick says: "Still, it does appear to solve
a real race, which we should close."
Acked-by: Nick Piggin <nickpiggin@yahoo.com.au> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The ring buffer allocates its buffers on pre-smp time (early_initcall).
It means that, at first, only the boot cpu buffer is allocated and
the ring-buffer cpumask only has the boot cpu set (cpu_online_mask).
Later, the secondary cpu will show up and the ring-buffer will be notified
about this event: the appropriate buffer will be allocated and the cpumask
will be updated.
Unfortunately, if !CONFIG_CPU_HOTPLUG, the ring-buffer will not be
notified about the secondary cpus, meaning that the cpumask will have
only the cpu boot set, and only one cpu buffer allocated.
We fix that by using cpu_possible_mask if !CONFIG_CPU_HOTPLUG.
This patch fixes the following warning with irqsoff tracer running:
Linus Torvalds [Wed, 18 Mar 2009 14:39:11 +0000 (07:39 -0700)]
Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound-2.6
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound-2.6:
ALSA: Fix vunmap and free order in snd_free_sgbuf_pages()
ALSA: mixart, fix lock imbalance
ALSA: pcm_oss, fix locking typo
ALSA: oss-mixer - Fixes recording gain control
ALSA: hda - Workaround for buggy DMA position on ATI controllers
ALSA: hda - Fix DMA mask for ATI controllers
ALSA: opl3sa2 - Fix NULL dereference when suspending snd_opl3sa2
After TASK_SIZE now gives the current size of the address space the
upgrade of a 64 bit process from 3 to 4 levels of page table needs
to use the arch_mmap_check hook to catch large mmap lengths. The
get_unmapped_area* functions need to check for -ENOMEM from the
arch_get_unmapped_area*, upgrade the page table and retry.
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Make page table walking on s390 more robust. The current code requires
that the pgd/pud/pmd/pte loop is only done for address ranges that are
below the end address of the last vma of the address space. But this
is not always true, e.g. the generic page table walker does not guarantee
this. Change TASK_SIZE/TASK_SIZE_OF to reflect the current size of the
address space. This makes the generic page table walker happy but it
breaks the upgrade of a 3 level page table to a 4 level page table.
To make the upgrade work again another fix is required.
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Gerald Schaefer [Wed, 18 Mar 2009 12:27:35 +0000 (13:27 +0100)]
[S390] Dont check for pfn_valid() in uaccess_pt.c
pfn_valid() actually checks for a valid struct page and not for a
valid pfn. Using xip mappings w/o struct pages, this will result in
-EFAULT returned by the (page table walk) user copy functions,
even though there is valid memory. Those user copy functions don't
need a struct page, so this patch just removes the pfn_valid() check.
Signed-off-by: Gerald Schaefer <gerald.schaefer@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Heiko Carstens [Wed, 18 Mar 2009 12:27:33 +0000 (13:27 +0100)]
[S390] topology: define SD_MC_INIT to fix performance regression
The default values for SD_MC_INIT cause an additional cpu usage of up
to 40% on some network benchmarks compared to the plain SD_CPU_INIT
values. So just define SD_MC_INIT to SD_CPU_INIT.
More tuning needs to be done.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
The implementation of __div64_31 for G5 machines is broken. The comments
in __div64_31 are correct, only the code does not do what the comments
say. The part "If the remainder has overflown subtract base and increase
the quotient" is only partially realized, the base is subtracted correctly
but the quotient is only increased if the dividend had the last bit set.
Using the correct instruction fixes the problem.
Cc: stable@kernel.org Reported-by: Frans Pop <elendil@planet.nl> Tested-by: Frans Pop <elendil@planet.nl> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
=====================================
[ BUG: bad unlock balance detected! ]
-------------------------------------
kthreadd/2 is trying to release lock (&rp->lock) at:
[<c06b3080>] pre_handler_kretprobe+0xea/0xf4
but there are no more locks to release!
other info that might help us debug this:
1 lock held by kthreadd/2:
#0: (rcu_read_lock){..--}, at: [<c06b2b24>] __atomic_notifier_call_chain+0x0/0x5a
During the selftest of irqsoff tracer, we do that:
/* disable interrupts for a bit */
local_irq_disable();
udelay(100);
local_irq_enable();
/* stop the tracing. */
tracing_stop();
/* check both trace buffers */
ret = trace_test_buffer(tr, NULL);
If a callsite performs a new max delay with irqs off just after
tracing_stop, update_max_tr_single() -> ring_buffer_swap_cpu()
will be called with the buffers disabled by tracing_stop(), hence
the warning, then ring_buffer_swap_cpu() return -EAGAIN and
update_max_tr_single() complains.
Fix it by also stopping the tracer before stopping the tracing globally.
A similar situation can happen with preemptoff and preemptirqsoff tracers
where we apply the same fix.
Carsten Emde [Wed, 18 Mar 2009 08:00:41 +0000 (09:00 +0100)]
tracing: fix command line to pid reverse map
Impact: fix command line to pid mapping
map_cmdline_to_pid[] is checked in trace_save_cmdline(), but never
updated. This results in stale pid to command line mappings and the
tracer output will associate the wrong comm string.
Thomas Gleixner [Wed, 18 Mar 2009 07:58:44 +0000 (08:58 +0100)]
tracing: fix trace_find_cmdline()
Impact: prevent stale command line output
In case there is no valid command line mapping for a pid
trace_find_cmdline() returns without updating the comm buffer. The
trace dump keeps the previous entry which results in confusing trace
output:
Thomas Gleixner [Wed, 18 Mar 2009 08:03:19 +0000 (09:03 +0100)]
tracing: replace the crude (unsigned) -1 hackery
Impact: cleanup
The command line recorder uses (unsigned) -1 to mark non mapped
entries in the pid to command line maps. The validity check is
completely unintuitive: idx >= SAVED_CMDLINES
There is no need for such casting games. Use a constant to mark
unmapped entries and check for that constant to make the code readable
and understandable.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Steven Rostedt <srostedt@redhat.com> Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <new-submission> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Thomas Gleixner [Wed, 18 Mar 2009 07:56:58 +0000 (08:56 +0100)]
tracing: stop command line recording when tracing is disabled
Impact: prevent overwrite of command line entries
When the tracer is stopped the command line recording continues to
record. The check for tracing_is_on() is not sufficient here as the
ringbuffer status is not affected by setting
debug/tracing/tracing_enabled to 0. On a non idle system this can
result in the loss of the command line information for the stopped
trace, which makes the trace harder to read and analyse.
Check tracer_enabled to allow further recording.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Steven Rostedt <srostedt@redhat.com> Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <new-submission> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Takashi Iwai [Tue, 17 Mar 2009 13:00:06 +0000 (14:00 +0100)]
ALSA: Fix vunmap and free order in snd_free_sgbuf_pages()
In snd_free_sgbuf_pags(), vunmap() is called after releasing the SG
pages, and it causes errors on Xen as Xen manages the pages
differently. Although no significant errors have been reported on
the actual hardware, this order should be fixed other way round,
first vunmap() then free pages.
Cc: Jan Beulich <jbeulich@novell.com> Cc: <stable@kernel.org> Signed-off-by: Takashi Iwai <tiwai@suse.de>
Viral Mehta [Tue, 10 Mar 2009 14:43:18 +0000 (15:43 +0100)]
ALSA: oss-mixer - Fixes recording gain control
At the time of initialization, SNDRV_MIXER_OSS_PRESENT_PVOLUME bit is not
set for MIC (slot 7).
So, the same should not be checked when an application tries to do gain
control for audio recording devices.
Just check slot->present for SNDRV_MIXER_OSS_PRESENT_CVOLUME independently.
Verified with a simple application which opens /dev/dsp for recording and
/dev/mixer for volume control.
Takashi Iwai [Tue, 17 Mar 2009 06:49:14 +0000 (07:49 +0100)]
ALSA: hda - Workaround for buggy DMA position on ATI controllers
The position-buffer on ATI controllers are unreliable as well as
on VIA chips, thus the same workaround for DMA position reading as
VIA is useful for ATI.
Takashi Iwai [Tue, 17 Mar 2009 06:47:18 +0000 (07:47 +0100)]
ALSA: hda - Fix DMA mask for ATI controllers
ATI controllers (at least some SB0600 models) appear buggy to handle
64bit DMA. As a workaround, reset GCAP bit0 and let the driver to
use only 32bit DMA on these controllers.
Linus Torvalds [Wed, 18 Mar 2009 03:55:40 +0000 (20:55 -0700)]
Merge branch 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4
* 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4:
ext4: fix bb_prealloc_list corruption due to wrong group locking
ext4: fix bogus BUG_ONs in in mballoc code
ext4: Print the find_group_flex() warning only once
ext4: fix header check in ext4_ext_search_right() for deep extent trees.
Steven Rostedt [Tue, 17 Mar 2009 23:59:53 +0000 (19:59 -0400)]
tracing: make sched_switch stop/start light weight
The stopping and starting of a tracer should be light weight and
be able to be called in all contexts. The sched_switch grabbed
mutexes in the start/stop functions. This patch changes it to a
simple variable, on/off.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Witold Baryluk [Tue, 17 Mar 2009 20:15:44 +0000 (21:15 +0100)]
tracing: optimization of branch tracer
Impact: better performance for if branch tracer
Use an array to count the hit and misses of a conditional instead
of using another conditional. This cuts down on saturation of branch
predictions and increases performance of modern pipelined architectures.
Signed-off-by: Witold Baryluk <baryluk@smp.if.uj.edu.pl> Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Masami Hiramatsu [Mon, 16 Mar 2009 22:13:36 +0000 (18:13 -0400)]
module: fix refptr allocation and release order
Impact: fix ref-after-free crash on failed module load
Fix refptr bug: Change refptr allocation and release order not to access a module
data structure pointed by 'mod' after freeing mod->module_core.
This bug will cause kernel panic(e.g. failed to find undefined symbols).
This bug was reported on systemtap bugzilla.
http://sources.redhat.com/bugzilla/show_bug.cgi?id=9927
Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com> Cc: Eric Dumazet <dada1@cosmosbay.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Thomas Bartosik [Mon, 16 Mar 2009 15:04:38 +0000 (16:04 +0100)]
USB: storage: Unusual USB device Prolific 2507 variation added
The "c-enter" USB to Toshiba 1.8" IDE enclosure needs special treatment
to work flawlessly. This patch is absolutely trivial, as the integrated
USB-IDE bridge is already identified to be an "unusual" device, only the
bcdDevice is different (lower) to the bcdDeviceMin already included in
the kernel.
It is a Prolific 2507 bridge.
Dirk Hohndel [Sun, 15 Mar 2009 03:47:39 +0000 (20:47 -0700)]
USB: Add Vendor/Product ID for new CDMA U727 to option driver
* newer versions of the Novatel Wireless U727 CDMA 3G USB stick
have a different Product ID (0x5010); adding this ID makes them
work just fine with the option driver
Signed-off-by: Moritz Muehlenhoff <jmm@debian.org> Tested-by: Jan Heitkoetter <devnull@heitkoetter.net> Cc: stable <stable@kernel.org> Signed-off-by: Phil Dibowitz <phil@ipom.com>
Dan Williams [Thu, 12 Mar 2009 10:53:00 +0000 (06:53 -0400)]
USB: Option: let cdc-acm handle Sony Ericsson F3507g / Dell 5530
The generic cdc-acm driver is now the best one to handle Sony Ericsson
F3507g-based devices (which the Dell 5530 is a rebrand of), now that all
the pieces are in place (ie, cac477e8f1038c41b6f29d3161ce351462ef3df7).
Removing the IDs from option allows cdc-acm to handle the device.
Signed-off-by: Dan Williams <dcbw@redhat.com> Cc: stable <stable@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Alan Stern [Mon, 16 Mar 2009 18:21:56 +0000 (14:21 -0400)]
USB: EHCI: expedite unlinks when the root hub is suspended
This patch (as1225) fixes a bug in ehci-hcd. The condition for
whether unlinked QHs can become IDLE should not be that the controller
is halted, but rather that the controller isn't running. In other
words when the root hub is suspended, the hardware doesn't own any
QHs.
This fixes a problem that can show up during hibernation: If a QH is
only partially unlinked when the root hub is frozen, then when the
root hub is thawed the QH won't be in the IDLE state. As a result it
can't be used properly for new URB submissions.
Karsten Wiese [Thu, 26 Feb 2009 00:47:48 +0000 (01:47 +0100)]
USB: EHCI: Fix isochronous URB leak
ehci-hcd uses usb_get_urb() and usb_put_urb() in an unbalanced way causing
isochronous URB's kref.counts incrementing once per usb_submit_urb() call.
The culprit is *usb being set to NULL when usb_put_urb() is called after URB
is given back.
Due to other fixes there is no need for ehci-hcd to deal with usb_get_urb()
nor usb_put_urb() anymore, so patch removes their usages in ehci-hcd.
Patch also makes ehci_to_hcd(ehci)->self.bandwidth_allocated adjust, if a
stream finishes.
Jan Dumon [Tue, 10 Mar 2009 16:29:47 +0000 (17:29 +0100)]
USB: unusual_devs: Add support for GI 0431 SD-Card interface
Enable the SD-Card interface on the GI 0431 HSUPA stick from Option.
The unusual_devs.h entry is necessary because the device descriptor is
vendor-specific. That prevents usb-storage from binding to it as an
interface driver.
Alan Stern [Mon, 9 Mar 2009 17:44:02 +0000 (13:44 -0400)]
USB: usbfs: keep async URBs until the device file is closed
The usbfs driver manages a list of completed asynchronous URBs. But
it is too eager to free the entries on this list: destroy_async() gets
called whenever an interface is unbound or a device is removed, and it
deallocates the outstanding struct async entries for all URBs on that
interface or device. This is wrong; the user program should be able
to reap an URB any time after it has completed, regardless of whether
or not the interface is still bound or the device is still present.
This patch (as1222) moves the code for deallocating the completed list
entries from destroy_async() to usbdev_release(). The outstanding
entries won't be freed until the user program has closed the device
file, thereby eliminating any possibility that the remaining URBs
might still be reaped.
This fixes a bug in which a program can hang in the USBDEVFS_REAPURB
ioctl when the device is unplugged.
Reported-and-tested-by: Martin Poupe <martin.poupe@upek.com> Signed-off-by: Alan Stern <stern@rowland.harvard.edu> Cc: stable <stable@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
J. Bruce Fields [Mon, 16 Mar 2009 22:34:20 +0000 (18:34 -0400)]
nfsd: nfsd should drop CAP_MKNOD for non-root
Since creating a device node is normally an operation requiring special
privilege, Igor Zhbanov points out that it is surprising (to say the
least) that a client can, for example, create a device node on a
filesystem exported with root_squash.
So, make sure CAP_MKNOD is among the capabilities dropped when an nfsd
thread handles a request from a non-root user.
Reported-by: Igor Zhbanov <izh1979@gmail.com> Cc: stable@kernel.org Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
Benny Halevy [Wed, 4 Mar 2009 21:05:35 +0000 (23:05 +0200)]
NFSD: provide encode routine for OP_OPENATTR
Although this operation is unsupported by our implementation
we still need to provide an encode routine for it to
merely encode its (error) status back in the compound reply.
Thanks for Bill Baker at sun.com for testing with the Sun
OpenSolaris' client, finding, and reporting this bug at
Connectathon 2009.
This bug was introduced in 2.6.27
Signed-off-by: Benny Halevy <bhalevy@panasas.com> Cc: stable@kernel.org Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
Linus Torvalds [Tue, 17 Mar 2009 17:02:35 +0000 (10:02 -0700)]
Avoid 64-bit "switch()" statements on 32-bit architectures
Commit ee6f779b9e0851e2f7da292a9f58e0095edf615a ("filp->f_pos not
correctly updated in proc_task_readdir") changed the proc code to use
filp->f_pos directly, rather than through a temporary variable. In the
process, that caused the operations to be done on the full 64 bits, even
though the offset is never that big.
That's all fine and dandy per se, but for some unfathomable reason gcc
generates absolutely horrid code when using 64-bit values in switch()
statements. To the point of actually calling out to gcc helper
functions like __cmpdi2 rather than just doing the trivial comparisons
directly the way gcc does for normal compares. At which point we get
link failures, because we really don't want to support that kind of
crazy code.
Fix this by just casting the f_pos value to "unsigned long", which
is plenty big enough for /proc, and avoids the gcc code generation issue.
Masami Hiramatsu [Mon, 16 Mar 2009 22:57:22 +0000 (18:57 -0400)]
prevent boosting kprobes on exception address
Don't boost at the addresses which are listed on exception tables,
because major page fault will occur on those addresses. In that case,
kprobes can not ensure that when instruction buffer can be freed since
some processes will sleep on the buffer.
Kumar Gala [Tue, 17 Mar 2009 15:17:50 +0000 (09:17 -0600)]
powerpc/mm: Respect _PAGE_COHERENT on classic ppc32 SW
Since we now set _PAGE_COHERENT in the Linux PTE we shouldn't be clearing
it out before we setup the SW TLB. Today all the SW TLB machines
(603/e300) that we support are non-SMP, however there are some errata on
some devices that cause us to set _PAGE_COHERENT via CPU_FTR_NEED_COHERENT.
Signed-off-by: Kumar Gala <galak@kernel.crashing.org> Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
Piotr Ziecik [Tue, 17 Mar 2009 15:17:50 +0000 (09:17 -0600)]
powerpc/5200: Enable CPU_FTR_NEED_COHERENT for MPC52xx
BestComm, a DMA engine in MPC52xx SoC, requires snooping when
CPU caches are enabled to work properly.
Adding CPU_FTR_NEED_COHERENT fixes NFS problems on MPC52xx machines
introduced by 'powerpc/mm: Fix handling of _PAGE_COHERENT in BAT setup
code' (sha1: 4c456a67f501b8b15542c7c21c28812bf88f484b).
Signed-off-by: Piotr Ziecik <kosmo@semihalf.com> Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
Linus Torvalds [Tue, 17 Mar 2009 15:13:17 +0000 (08:13 -0700)]
Fast TSC calibration: calculate proper frequency error bounds
In order for ntpd to correctly synchronize the clocks, the frequency of
the system clock must not be off by more than 500 ppm (or, put another
way, 1:2000), or ntpd will end up giving up on trying to synchronize
properly, and ends up reseting the clock in jumps instead.
The fast TSC PIT calibration sometimes failed this test - it was
assuming that the PIT reads always took about one microsecond each (2us
for the two reads to get a 16-bit timer), and that calibrating TSC to
the PIT over 15ms should thus be sufficient to get much closer than
500ppm (max 2us error on both sides giving 4us over 15ms: a 270 ppm
error value).
However, that assumption does not always hold: apparently some hardware
is either very much slower at reading the PIT registers, or there was
other noise causing at least one machine to get 700+ ppm errors.
So instead of using a fixed 15ms timing loop, this changes the fast PIT
calibration to read the TSC delta over the individual PIT timer reads,
and use the result to calculate the error bars on the PIT read timing
properly. We then successfully calibrate the TSC only if the maximum
error bars fall below 500ppm.
In the process, we also relax the timing to allow up to 25ms for the
calibration, although it can happen much faster depending on hardware.
Reported-and-tested-by: Jesper Krogh <jesper@krogh.cc> Cc: john stultz <johnstul@us.ibm.com> Cc: Thomas Gleixner <tglx@linutronix.de> Acked-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Linus Torvalds [Tue, 17 Mar 2009 14:58:26 +0000 (07:58 -0700)]
Fix potential fast PIT TSC calibration startup glitch
During bootup, when we reprogram the PIT (programmable interval timer)
to start counting down from 0xffff in order to use it for the fast TSC
calibration, we should also make sure to delay a bit afterwards to allow
the PIT hardware to actually start counting with the new value.
That will happens at the next CLK pulse (1.193182 MHz), so the easiest
way to do that is to just wait at least one microsecond after
programming the new PIT counter value. We do that by just reading the
counter value back once - which will take about 2us on PC hardware.
Reported-and-tested-by: john stultz <johnstul@us.ibm.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Tom Zanussi [Tue, 17 Mar 2009 06:20:59 +0000 (01:20 -0500)]
tracing: fix leak in event_format_read()
Impact: fix memory leak
If event_format_read() exits early due to nonzero ppos, the
previous kmalloc doesn't get freed - might as well do the
check before the kmalloc and avoid the problem.
Signed-off-by: Tom Zanussi <tzanussi@gmail.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: =?ISO-8859-1?Q?Fr=E9d=E9ric?= Weisbecker <fweisbec@gmail.com>
LKML-Reference: <1237270859.8033.141.camel@charm-linux> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Steven Rostedt [Tue, 17 Mar 2009 01:57:17 +0000 (21:57 -0400)]
tracing: stop comm recording on tracing off
Impact: fix for losing comms in trace
The command lines of tasks are cached at sched switch to not need
to record them at every trace point. Disabling the tracing on stops
the recording of traces, but does not stop the caching of command lines.
When the tracing is off the cache may overflow and cause the tracing
to show incorrect tasks matching the PIDs.
This patch disables prevents updates to the comm cache when the ring buffer
is off.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
projects / linux-2.6-omap-h63xx.git / log