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Create a bit to signal that a napi_disable() is in progress.
This sets up infrastructure such that net_rx_action() can generically
break out of the ->poll() loop on a NAPI context that has a pending
napi_disable() yet is being bombed with packets (and thus would
otherwise poll endlessly and not allow the napi_disable() to finish).
Now, what napi_disable() does is first set the NAPI_STATE_DISABLE bit
(to indicate that a disable is pending), then it polls for the
NAPI_STATE_SCHED bit, and once the NAPI_STATE_SCHED bit is acquired
the NAPI_STATE_DISABLE bit is cleared. Here, the test_and_set_bit()
provides the necessary memory barrier between the various bitops.
napi_schedule_prep() now tests for a pending disable as it's first
action and won't try to obtain the NAPI_STATE_SCHED bit if a disable
is pending.
As a result, we can remove the netif_running() check in
netif_rx_schedule_prep() because the NAPI disable pending state serves
this purpose. And, it does so in a NAPI centric manner which is what
we really want.
Signed-off-by: David S. Miller <davem@davemloft.net>
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It is pointless, because everything that can make a device go away
will do a napi_disable() first.
The main impetus behind this is that now we can legally do a NAPI
completion in generic code like net_rx_action() which a following
changeset needs to do. net_rx_action() can only perform actions
in NAPI centric ways, because there may be a one to many mapping
between NAPI contexts and network devices (SKY2 is one example).
We also want to get rid of this because it's an extra atomic in the
NAPI paths, and also because it is one of the last instances where the
NAPI interfaces care about net devices.
The one remaining netdev detail the NAPI stuff cares about is the
netif_running() check which will be killed off in a subsequent
changeset.
Signed-off-by: David S. Miller <davem@davemloft.net>
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This patch fixes the parsing of the RX data header channel field.
The current code parses the header incorrectly and passes a wrong
channel number and frequency for each frame to mac80211.
The FIXMEs added by this patch don't matter for now as the code
where they live won't get executed anyway. They will be fixed later.
Signed-off-by: Michael Buesch <mb@bu3sch.de>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
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easy to trigger as user with sfuzz.
irda_create() is quiet on unknown sock->type,
match this behaviour for SOCK_DGRAM unknown protocol
Signed-off-by: maximilian attems <max@stro.at>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Some recent changes completely removed accounting for the FORWARD_TSN
parameter length in the INIT and INIT-ACK chunk. This is wrong and
should be restored.
Signed-off-by: Vlad Yasevich <vladislav.yasevich@hp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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When processing an unexpected INIT chunk, we do not need to
do any preservation of the old AUTH parameters. In fact,
doing such preservations will nullify AUTH and allow connection
stealing.
Signed-off-by: Vlad Yasevich <vladislav.yasevich@hp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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The even should be called SCTP_AUTHENTICATION_INDICATION.
Signed-off-by: Vlad Yasevich <vladislav.yasevich@hp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Signed-off-by: Chas Williams <chas@cmf.nrl.navy.mil>
Signed-off-by: David S. Miller <davem@davemloft.net>
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This should fix the kernel warn/oops reported while routing.
The tulip driver has a fencepost bug with new NAPI in 2.6.24
It has an off by one bug if a full quantum is reached.
Signed-off-by: Stephen Hemminger <shemminger@linux-foundation.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
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meth didn't set a valid mac address during probing, but later during
open. Newer kernel refuse to open device with 00:00:00:00:00:00 as mac
address -> dead ethernet. This patch sets the mac address in the probe
function and uses only the mac address from the netdevice struct when
setting up the hardware.
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
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This was missed when commit e2ac455a18806b31c2d0da0a51d8740af5010b7a
fixed the compile errors in drivers/net/netx-eth.c caused by
commit 09f75cd7bf13720738e6a196cc0107ce9a5bd5a0.
Signed-off-by: Adrian Bunk <adrian.bunk@movial.fi>
Signed-off-by: David S. Miller <davem@davemloft.net>
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The recent changes for ip command line processing fixed some problems
but unfortunately broke some common usage scenarios. In current
2.6.24-rc6 the following command line results in no IP address
assignment, which is surely a regression:
ip=10.0.2.15::10.0.2.2:255.255.255.0::eth0:off
Please find below a patch that works for all cases I can find.
Signed-off-by: Amos Waterland <apw@us.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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We currently check that iph->ihl is bounded by the real length and that
the real length is greater than the minimum IP header length. However,
we did not check the caes where iph->ihl is less than the minimum IP
header length.
This breaks because some ip_fast_csum implementations assume that which
is quite reasonable.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Signed-off-by: David S. Miller <davem@davemloft.net>
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It is possible for the TX ring to have packets sit in it for unbounded
amounts of time.
The only way to defer TX interrupts in the chip is to periodically set
"mark" bits, when processing of a TX descriptor with the mark bit set
is complete it triggers the interrupt for the TX queue's LDG.
A consequence of this kind of scheme is that if packet flow suddenly
stops, the remaining TX packets will just sit there.
If this happens, since those packets could be charged to TCP socket
send queues, such sockets could get stuck.
The simplest solution is to divorce the socket ownership of the packet
once the device takes the SKB, by using skb_orphan() in
niu_start_xmit().
In hindsight, it would have been much nicer if the chip provided two
interrupt sources for TX (like basically every other ethernet chip
does). Namely, keep the "mark" bit, but also signal the LDG when the
TX queue becomes completely empty. That way there is no need to have
a deadlock breaker like this.
Signed-off-by: David S. Miller <davem@davemloft.net>
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Noticed by Paul Lodridge.
Signed-off-by: David S. Miller <davem@davemloft.net>
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niu_slowpath_interrupt() expects values to be setup in lp->{v0,v1,v2}
but they aren't. That's only done by niu_schedule_napi() which is
done later in the interrupt path.
If niu_rx_error() returns zero, and v0 is clear, hit the
RX_DMA_CTL_STATE register with a RX_DMA_CTL_STAT_MEX.
Only emit verbose RX error logs if a fatal channel or port error is
signalled. Other cases will be recorded into statistics by
niu_log_rxchan_errors().
Signed-off-by: David S. Miller <davem@davemloft.net>
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Roland Westrelin did a great analysis of a long standing thinko in the
return path of futex_lock_pi.
While we fixed the lock steal case long ago, which was easy to trigger,
we never had a test case which exposed this problem and stupidly never
thought about the reverse lock stealing scenario and the return to user
space with a stale state.
When a blocked tasks returns from rt_mutex_timed_locked without holding
the rt_mutex (due to a signal or timeout) and at the same time the task
holding the futex is releasing the futex and assigning the ownership of
the futex to the returning task, then it might happen that a third task
acquires the rt_mutex before the final rt_mutex_trylock() of the
returning task happens under the futex hash bucket lock. The returning
task returns to user space with ETIMEOUT or EINTR, but the user space
futex value is assigned to this task. The task which acquired the
rt_mutex fixes the user space futex value right after the hash bucket
lock has been released by the returning task, but for a short period of
time the user space value is wrong.
Detailed description is available at:
https://bugzilla.redhat.com/show_bug.cgi?id=400541
The fix for this is the same as we do when the rt_mutex was acquired by
a higher priority task via lock stealing from the designated new owner.
In that case we already fix the user space value and the internal
pi_state up before we return. This mechanism can be used to fixup the
above corner case as well. When the returning task, which failed to
acquire the rt_mutex, notices that it is the designated owner of the
futex, then it fixes up the stale user space value and the pi_state,
before returning to user space. This happens with the futex hash bucket
lock held, so the task which acquired the rt_mutex is guaranteed to be
blocked on the hash bucket lock. We can access the rt_mutex owner, which
gives us the pid of the new owner, safely here as the owner is not able
to modify (release) it while waiting on the hash bucket lock.
Rename the "curr" argument of fixup_pi_state_owner() to "newowner" to
avoid confusion with current and add the check for the stale state into
the failure path of rt_mutex_trylock() in the return path of
unlock_futex_pi(). If the situation is detected use
fixup_pi_state_owner() to assign everything to the owner of the
rt_mutex.
Pointed-out-and-tested-by: Roland Westrelin <roland.westrelin@sun.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Cleaning out all the incorrect 'no change made' checks for termios
settings showed up a problem with the PL2303. The hardware here seems to
lose sync and bits if you tell it to make no changes. This shows up with
a real world application.
To fix this the driver check for meaningful hardware changes is restored
but doing the tests correctly and as a tty layer function so it doesn't
get duplicated wrongly everywhere if other drivers turn out to need it.
Signed-off-by: Alan Cox <alan@redhat.com>
Tested-by: Mirko Parthey <mirko.parthey@informatik.tu-chemnitz.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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hfs seems prone to bad things when it encounters on disk corruption. Many
values are read from disk, and used as lengths to memcpy, as an example.
This patch fixes up several of these problematic cases.
o sanity check the on-disk maximum key lengths on mount
(these are set to a defined value at mkfs time and shouldn't differ)
o check on-disk node keylens against the maximum key length for each tree
o fix hfs_btree_open so that going out via free_tree: doesn't wind
up in hfs_releasepage, which wants to follow the very pointer
we were trying to set up:
HFS_SB(sb)->cat_tree = hfs_btree_open()
...
failure gets to hfs_releasepage and tries
to follow HFS_SB(sb)->cat_tree
Tested with the fsfuzzer; it survives more than it used to.
Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Cc: Roman Zippel <zippel@linux-m68k.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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When using FLAT_MEMORY and ARCH_PFN_OFFSET is not 0, the kernel crashes in
memmap_init_zone(). This bug got introduced by commit
c713216deebd95d2b0ab38fef8bb2361c0180c2d
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Acked-by: Mel Gorman <mel@csn.ul.ie>
Cc: Bob Picco <bob.picco@hp.com>
Cc: Dave Hansen <haveblue@us.ibm.com>
Cc: Andy Whitcroft <apw@shadowen.org>
Cc: Andi Kleen <ak@muc.de>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: "Keith Mannthey" <kmannth@gmail.com>
Cc: "Luck, Tony" <tony.luck@intel.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Yasunori Goto <y-goto@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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with gcc-3.2
Rework this functions so that gcc-3.2 can successfully perform
constant-folding.
Signed-off-by: Jean Delvare <khali@linux-fr.org>
Cc: Jaroslav Kysela <perex@suse.cz>
Cc: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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gcc 3.2 has a hard time coping with the code in dmi_id_init():
drivers/built-in.o(.init.text+0x789e): In function `dmi_id_init':
: undefined reference to `__you_cannot_kmalloc_that_much'
make: *** [.tmp_vmlinux1] Error 1
Moving half of the code to a separate function seems to help. This is a
no-op for gcc 4.1 which will successfully inline the code anyway.
Signed-off-by: Jean Delvare <khali@linux-fr.org>
Cc: Dave Airlie <airlied@linux.ie>
Tested-by: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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This patch adds the array length of "free_area.free_list" to the vmcoreinfo
data so that makedumpfile (dump filtering command) can exclude all free pages
in linux-2.6.24.
makedumpfile creates a small dumpfile by excluding unnecessary pages for the
analysis. To distinguish unnecessary pages, makedumpfile gets the vmcoreinfo
data which has the minimum debugging information only for dump filtering.
In 2.6.24-rc1 or later, the free_area.free_list is an array which has one list
for each migrate types instead of a single list. makedumpfile needs the array
length of "free_area.free_list" and the vmcoreinfo data should contain it.
Signed-off-by: Huang Ying <ying.huang@intel.com>
Tested-by: Ken'ichi Ohmichi <oomichi@mxs.nes.nec.co.jp>
Acked-by: Simon Horman <horms@verge.net.au>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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This patch corrects some erroneous dentry handling in eCryptfs.
If there is a problem creating the lower file, then there is nothing that
the persistent lower file can do to really help us. This patch makes a
vfs_create() failure in the lower filesystem always lead to an
unconditional do_create failure in eCryptfs.
Under certain sequences of operations, the eCryptfs dentry can remain in
the dcache after an unlink. This patch calls d_drop() on the eCryptfs
dentry to correct this.
eCryptfs has no business calling d_delete() directly on a lower
filesystem's dentry. This patch removes the call to d_delete() on the
lower persistent file's dentry in ecryptfs_destroy_inode().
(Thanks to David Kleikamp, Eric Sandeen, and Jeff Moyer for helping
identify and resolve this issue)
Signed-off-by: Michael Halcrow <mhalcrow@us.ibm.com>
Cc: Dave Kleikamp <shaggy@austin.ibm.com>
Cc: Eric Sandeen <sandeen@redhat.com>
Cc: Jeff Moyer <jmoyer@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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The use of get_zeroed_page() with __GFP_HIGHMEM is invalid. Use
alloc_page() with __GFP_ZERO instead of invalid get_zeroed_page().
(This patch is only compile tested)
Cc: Carsten Otte <cotte@de.ibm.com>
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Acked-by: Hugh Dickins <hugh@veritas.com>
Acked-by: Carsten Otte <cotte@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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We currently do not wait for the block from the missing device to be
computed from parity before copying data to the new stripe layout.
The change in the raid6 code is not techincally needed as we don't delay
data block recovery in the same way for raid6 yet. But making the change
now is safer long-term.
This bug exists in 2.6.23 and 2.6.24-rc
Cc: <stable@kernel.org>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Acked-by: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Commit 664cceb0093b755739e56572b836a99104ee8a75 changed the parameters of
the function make_key_ref(). The macros that are used in case CONFIG_KEY
is not defined did not change.
Cc: David Howells <dhowells@redhat.com>
Signed-off-by: Sebastian Siewior <sebastian@breakpoint.cc>
Acked-by: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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On large partition, scanning the free clusters is very slow if users
doesn't use "usefree" option.
For optimizing it, this patch uses sb_breadahead() to read of FAT
sectors. On some user's 15GB partition, this patch improved it very
much (1min => 600ms).
The following is the result of 2GB partition on my machine.
without patch:
root@devron (/)# time df -h > /dev/null
real 0m1.202s
user 0m0.000s
sys 0m0.440s
with patch:
root@devron (/)# time df -h > /dev/null
real 0m0.378s
user 0m0.012s
sys 0m0.168s
Signed-off-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Fix a glitch reported by lockdep in the spi_bitbang code: it needs to
consistently block IRQs when holding that spinlock.
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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With CPU_HOTPLUG=n:
WARNING: vmlinux.o(.text+0x104f8): Section mismatch: reference to .init.text:fork_idle (between
'do_fork_idle' and 'lapic_timer_broadcast')
do_fork_idle() needs to be __cpuinit. It can be static as well.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/roland/infiniband
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/roland/infiniband:
IB/srp: Release transport before removing host
IB/mlx4: Fix value of pkey_index in QP1 completions
MAINTAINERS: Update Sean Hefty's email address
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The documented call sequence for removing a host is to call the
transport xxx_remove_host() prior to scsi_remove_host(). The SRP
transport used to crash when that order was followed, but as it is now
fixed, use the documented order.
Signed-off-by: David Dillow <dillowda@ornl.gov>
Acked-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
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Fix the value of pkey_index in completions to get a valid value for
GSI QPs. Without this fix, incoming GSI packets on port 2 get an
invalid P_Key index in the completion, which prevents the MAD layer
from sending back a response, which can make the second port of
ConnectX HCAs completely useless.
Signed-off-by: Dotan Barak <dotanb@dev.mellanox.co.il>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
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This reverts commit 57a04513cb35086d54bcb2cb92e6627fc8fa0fae.
Harald Dunkel reports that it broke sound for him:
"Alsa stopped working for me. I still can access /dev/dsp, change the
volume and so on, but the speakers are quiet."
Reverting it fixed things for him.
Reported-and-tested-by: Harald Dunkel <harald.dunkel@t-online.de>
Acked-by: Takashi Iwai <tiwai@suse.de>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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My Unix email account is being discontinued at end of Q1 '08.
Signed-off-by: Sean Hefty <sean.hefty@intel.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
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The ac_ppid field reported in process accounting records
should match what getppid() would have returned to that
process, regardless of whether a debugger is attached.
Signed-off-by: Roland McGrath <roland@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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The pr_ppid field reported in core dumps should match what
getppid() would have returned to that process, regardless of
whether a debugger is attached.
Signed-off-by: Roland McGrath <roland@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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* 'upstream' of git://ftp.linux-mips.org/pub/scm/upstream-linus:
[MIPS] Fix CONFIG_BOOT_RAW.
[MIPS] Assume R4000/R4400 newer than 3.0 don't have the mfc0 count bug
[MIPS] Fix IP32 breakage
[MIPS] Alchemy: Fix use of __init code bug exposed by modpost warning
[MIPS] Move inclusing of kernel/time/Kconfig menu to appropriate place
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* git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/v4l-dvb:
V4L/DVB (6916): ivtv: udelay has to be changed *after* the eeprom was read, not before
V4L/DVB (6944a): Fix Regression VIDIOCGMBUF ioctl hangs on bttv driver
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This was broken by 017e3a492683b32d17dcd1b13b279745cc656073 (lmo) /
396a2ae08e5080b140330645743ab2567f6bc426 (kernel.org).
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
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This seems as reasonable assumption and gets some SNI machines to work
which currently must rely on the cp0 counter as clocksource.
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
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- suppress master aborts during config read
- set io_map_base
- only fixup end of iomem resource to avoid failing request_resource
in serial driver
- killed useless setting of crime_int bit, which caused wrong interrupts
- use physcial address for serial port platform device and let 8250
driver do the ioremap
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
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WARNING: vmlinux.o(.text+0x1ca608): Section mismatch: reference to
.init.text: add_wired_entry (between 'config_access' and 'config_read')
by refactoring the code calling add_wired_entry() from config_access() to
a separate function which is called from aau1x_pci_setup(). While at it:
- make some unnecassarily global variables 'static';
- fix the letter case, whitespace, etc. in the comments...
Signed-off-by: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
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CONFIG_NO_HZ, CONFIG_HIGH_RES_TIMERS should be selected in "Kernel
type" menu, not in "CPU selection" menu.
Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
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not before
The eeprom decides which Hauppauge model it is, so the decision whether to
use an udelay of 5 or 10 needs to be taken after reading the eeprom, not
before.
Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>
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Fix bttv VIDIOCGMBUF locking like done in commit
820eacd84cff23b76693f4be1e28feb672f4488f.
Signed-off-by: Gregor Jasny <gjasny@web.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>
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* master.kernel.org:/home/rmk/linux-2.6-arm:
[ARM] 4691/1: add missing i2c_board_info struct for at91rm9200
[ARM] 4735/1: Unbreak pxa25x suspend/resume
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make randconfig bootup testing found that the cpufreq code
crashes on bootup, if the powernow-k8 driver is enabled and
if maxcpus=1 passed on the boot line to a !CONFIG_HOTPLUG_CPU
kernel.
First lockdep found out that there's an inconsistent unlock
sequence:
=====================================
[ BUG: bad unlock balance detected! ]
-------------------------------------
swapper/1 is trying to release lock (&per_cpu(cpu_policy_rwsem, cpu)) at:
[<ffffffff806ffd8e>] unlock_policy_rwsem_write+0x3c/0x42
but there are no more locks to release!
Call Trace:
[<ffffffff806ffd8e>] unlock_policy_rwsem_write+0x3c/0x42
[<ffffffff80251c29>] print_unlock_inbalance_bug+0x104/0x12c
[<ffffffff80252f3a>] mark_held_locks+0x56/0x94
[<ffffffff806ffd8e>] unlock_policy_rwsem_write+0x3c/0x42
[<ffffffff807008b6>] cpufreq_add_dev+0x2a8/0x5c4
...
then shortly afterwards the cpufreq code crashed on an assert:
------------[ cut here ]------------
kernel BUG at drivers/cpufreq/cpufreq.c:1068!
invalid opcode: 0000 [1] SMP
[...]
Call Trace:
[<ffffffff805145d6>] sysdev_driver_unregister+0x5b/0x91
[<ffffffff806ff520>] cpufreq_register_driver+0x15d/0x1a2
[<ffffffff80cc0596>] powernowk8_init+0x86/0x94
[...]
---[ end trace 1e9219be2b4431de ]---
the bug was caused by maxcpus=1 bootup, which brought up the
secondary core as !cpu_online() but !cpu_is_offline() either,
which on on !CONFIG_HOTPLUG_CPU is always 0 (include/linux/cpu.h):
/* CPUs don't go offline once they're online w/o CONFIG_HOTPLUG_CPU */
static inline int cpu_is_offline(int cpu) { return 0; }
but the cpufreq code uses cpu_online() and cpu_is_offline() in
a mixed way - the low-level drivers use cpu_online(), while
the cpufreq core uses cpu_is_offline(). This opened up the
possibility to add the non-initialized sysdev device of the
secondary core:
cpufreq-core: trying to register driver powernow-k8
cpufreq-core: adding CPU 0
powernow-k8: BIOS error - no PSB or ACPI _PSS objects
cpufreq-core: initialization failed
cpufreq-core: adding CPU 1
cpufreq-core: initialization failed
which then blew up. The fix is to make cpu_is_offline() always
the negation of cpu_online(). With that fix applied the kernel
boots up fine without crashing:
Calling initcall 0xffffffff80cc0510: powernowk8_init+0x0/0x94()
powernow-k8: Found 1 AMD Athlon(tm) 64 X2 Dual Core Processor 3800+ processors (1 cpu cores) (version 2.20.00)
powernow-k8: BIOS error - no PSB or ACPI _PSS objects
initcall 0xffffffff80cc0510: powernowk8_init+0x0/0x94() returned -19.
initcall 0xffffffff80cc0510 ran for 19 msecs: powernowk8_init+0x0/0x94()
Calling initcall 0xffffffff80cc328f: init_lapic_nmi_sysfs+0x0/0x39()
We could fix this by making CPU enumeration aware of max_cpus, but that
would be more fragile IMO, and the cpu_online(cpu) != cpu_is_offline(cpu)
possibility was quite confusing and a continuous source of bugs too.
Most distributions have kernels with CPU hotplug enabled, so this bug
remained hidden for a long time.
Bug forensics:
The broken cpu_is_offline() API variant was introduced via:
commit a59d2e4e6977e7b94e003c96a41f07e96cddc340
Author: Rusty Russell <rusty@rustcorp.com.au>
Date: Mon Mar 8 06:06:03 2004 -0800
[PATCH] minor cleanups for hotplug CPUs
( this predates linux-2.6.git, this commit is available from Thomas's
historic git tree. )
Then 1.5 years later the cpufreq code made use of it:
commit c32b6b8e524d2c337767d312814484d9289550cf
Author: Ashok Raj <ashok.raj@intel.com>
Date: Sun Oct 30 14:59:54 2005 -0800
[PATCH] create and destroy cpufreq sysfs entries based on cpu notifiers
+ if (cpu_is_offline(cpu))
+ return 0;
which is a correct use of the subtly broken new API. v2.6.15 then
shipped with this bug included.
then it took two more years for random-kernel qa to hit it.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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