| Age | Commit message (Collapse) | Author |
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* git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6:
[CRYPTO] hmac: Avoid calling virt_to_page on key
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git://git.kernel.org/pub/scm/linux/kernel/git/paulus/powerpc
* 'merge' of git://git.kernel.org/pub/scm/linux/kernel/git/paulus/powerpc: (23 commits)
[POWERPC] Remove leftover printk in isa-bridge.c
[POWERPC] Remove duplicate #include
[POWERPC] Initialize lockdep earlier
[POWERPC] Document when printk is useable
[POWERPC] Fix bogus paca->_current initialization
[POWERPC] Fix of_i2c include for module compilation
[POWERPC] Make default cputable entries reflect selected CPU family
[POWERPC] spufs: lockdep annotations for spufs_dir_close
[POWERPC] spufs: don't requeue victim contex in find_victim if it's not in spu_run
[POWERPC] 4xx: Fix PCI mem in sequoia DTS
[POWERPC] 4xx: Add endpoint support to 4xx PCIe driver
[POWERPC] 4xx: Fix problem with new TLB storage attibute fields on 440x6 core
[POWERPC] spufs: spu_create should send inotify IM_CREATE event
[POWERPC] spufs: handle faults while the context switch pending flag is set
[POWERPC] spufs: fix concurrent delivery of class 0 & 1 exceptions
[POWERPC] spufs: try to route SPU interrupts to local node
[POWERPC] spufs: set SPU_CONTEXT_SWITCH_PENDING before synchronising SPU irqs
[POWERPC] spufs: don't acquire state_mutex interruptible while performing callback
[POWERPC] spufs: update master runcntl with context lock held
[POWERPC] spufs: fix post-stopped update of MFC_CNTL register
...
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m32r can use the generic sys_pipe implementation.
The current sys_pipe implementation on m32r only differes from the
generic one by passing a lot of additional unused registers to sys_pipe.
Reviewed and tested by Hirokazu Takata.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Hirokazu Takata <takata@linux-m32r.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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The cris implementation of sys_pipe only differs from the generic one
by taking the BKL before calling do_pipe which isn't not nessecary.
Just kill the cris implementation and use the generic one.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-2.6:
sit: Add missing kfree_skb() on pskb_may_pull() failure.
tipc: Increase buffer header to support worst-case device
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Linus found a logic bug: we ignore the version number in a module's
vermagic string if we have CONFIG_MODVERSIONS set, but modversions
also lets through a module with no __versions section for modprobe
--force (with tainting, but still).
We should only ignore the start of the vermagic string if the module
actually *has* crcs to check. Rather than (say) having an
entertaining hissy fit and creating a config option to work around the
buggy code.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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We allow missing __versions sections, because modprobe --force strips
it. It makes less sense to allow sections where there's no version
for a specific symbol the module uses, so disallow that.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Don't allow a module built without versions altogether to be inserted
into a kernel which expects modversions.
modprobe --force will strip vermagic as well as modversions, so it
won't be effected, but this will make sure that a
non-CONFIG_MODVERSIONS module won't be accidentally inserted into a
CONFIG_MODVERSIONS kernel.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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This printk() appears twice in the same function. Only the latter one
in the inval_range: section appears to be legitimate.
Signed-off-by: Nate Case <ncase@xes-inc.com>
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
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Remove duplicate #include of <asm/prom.h> in
arch/powerpc/kernel/btext.c.
Signed-off-by: Huang Weiyi <weiyi.huang@gmail.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>
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This moves lockdep_init() to before udbg_early_init() as the later
can call things that acquire spinlocks etc... This also makes printk
safer to use earlier.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
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When debugging early boot problems, it's common to sprinkle printk's
all over the place. However, on 64-bit powerpc, this can lead to
memory corruption if done too early due to the PACA pointer and
lockdep core not being initialized.
This adds some comments to early_setup() that document when it is
safe to do so in order to save time for whoever has to debug that
stuff next.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
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When doing lockdep, I had two patches to initialize paca->_current
early, one bogus, and one correct. Unfortunately both got merged
as the bad one ended up being part of the main lockdep patch by
mistake. This causes memory corruption at boot. This removes
the offending code.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
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Remove #ifdef CONFIG_OF_I2C as this breaks module compilation.
Drivers using this header should depend on OF_I2C anyways, so
there's no need to make this conditional.
Signed-off-by: Jochen Friedrich <jochen@scram.de>
Signed-off-by: Paul Mackerras <paulus@samba.org>
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Changes the cputable so that various CPU families that have an exclusive
CONFIG_ option have a more sensible default entry to use if the specific
processor hasn't been identified.
This makes the kernel more generally useful when booted on an unknown
PVR for things like new 4xx variants.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
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master.kernel.org:/pub/scm/linux/kernel/git/jwboyer/powerpc-4xx into merge
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Noticed by Paul Marks <paul@pmarks.net>.
Signed-off-by: David S. Miller <davem@davemloft.net>
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This patch increases the headroom TIPC reserves in each sk_buff
to accommodate the largest possible link level device header.
Signed-off-by: Allan Stephens <allan.stephens@windriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-2.6: (32 commits)
net: Added ASSERT_RTNL() to dev_open() and dev_close().
can: Fix can_send() handling on dev_queue_xmit() failures
netns: Fix arbitrary net_device-s corruptions on net_ns stop.
netfilter: Kconfig: default DCCP/SCTP conntrack support to the protocol config values
netfilter: nf_conntrack_sip: restrict RTP expect flushing on error to last request
macvlan: Fix memleak on device removal/crash on module removal
net/ipv4: correct RFC 1122 section reference in comment
tcp FRTO: SACK variant is errorneously used with NewReno
e1000e: don't return half-read eeprom on error
ucc_geth: Don't use RX clock as TX clock.
cxgb3: Use CAP_SYS_RAWIO for firmware
pcnet32: delete non NAPI code from driver.
fs_enet: Fix a memory leak in fs_enet_mdio_probe
[netdrvr] eexpress: IPv6 fails - multicast problems
3c59x: use netstats in net_device structure
3c980-TX needs EXTRA_PREAMBLE
fix warning in drivers/net/appletalk/cops.c
e1000e: Add support for BM PHYs on ICH9
uli526x: fix endianness issues in the setup frame
uli526x: initialize the hardware prior to requesting interrupts
...
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* git://git.kernel.org/pub/scm/linux/kernel/git/davem/sparc-2.6:
sparc: Fix SA_ONSTACK signal handling.
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This reverts commit 9f8daccaa05c14e5643bdd4faf5aed9cc8e6f11e, which was
reported to break X startup (xf86-video-ati-6.8.0). See
http://bugs.freedesktop.org/show_bug.cgi?id=15523
for details.
Reported-by: Laurence Withers <l@lwithers.me.uk>
Cc: Gary Hade <garyhade@us.ibm.com>
Cc: Greg KH <greg@kroah.com>
Cc: Jan Beulich <jbeulich@novell.com>
Cc: "Jun'ichi Nomura" <j-nomura@ce.jp.nec.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/mingo/linux-2.6-sched-fixes
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mingo/linux-2.6-sched-fixes:
sched: fix weight calculations
semaphore: fix
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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] soc at91 minor bug fixes
[ALSA] soc - at91-pcm - Fix line wrapping
pcspkr: fix dependancies
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<linux/sched.h> we included twice.
Signed-off-by: Huang Weiyi <weiyi.huang@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Removed duplicated include files <linux/ptrace.h> and <linux/seq_file.h> in
fs/proc/task_mmu.c.
Signed-off-by: Huang Weiyi <weiyi.huang@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Fix allmodconfig build bug introduced in latest -git by commit
7c91f0624a9 ("V4L/DVB(7767): Move tuners to common/tuners"):
LD kernel/built-in.o
LD drivers/built-in.o
ld: drivers/media/built-in.o: No such file: No such file or directory
which happens if all media drivers are modular:
http://redhat.com/~mingo/misc/config-Wed_Apr_30_09_24_48_CEST_2008.bad
In that case there's no obj-y rule connecting all the built-in.o files and
the link tree breaks.
The fix is to add a guaranteed obj-y rule for the core vmlinux to build.
(which results in an empty object file if all media drivers are modular)
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
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/ehca: Wait for async events to finish before destroying QP
IB/ipath: Fix SDMA error recovery in absence of link status change
IB/ipath: Need to always request and handle PIO avail interrupts
IB/ipath: Fix count of packets received by kernel
IB/ipath: Return the correct opcode for RDMA WRITE with immediate
IB/ipath: Fix bug that can leave sends disabled after freeze recovery
IB/ipath: Only increment SSN if WQE is put on send queue
IB/ipath: Only warn about prototype chip during init
RDMA/cxgb3: Fix severe limit on userspace memory registration size
RDMA/cxgb3: Don't add PBL memory to gen_pool in chunks
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Make cpu_relax() invoke barrier() to be the same as other arches.
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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* 'for-linus' of git://git.kernel.dk/linux-2.6-block:
Revert "relay: fix splice problem"
docbook: fix bio missing parameter
block: use unitialized_var() in bio_alloc_bioset()
block: avoid duplicate calls to get_part() in disk stat code
cfq-iosched: make io priorities inherit CPU scheduling class as well as nice
block: optimize generic_unplug_device()
block: get rid of likely/unlikely predictions in merge logic
vfs: splice remove_suid() cleanup
cfq-iosched: fix RCU race in the cfq io_context destructor handling
block: adjust tagging function queue bit locking
block: sysfs store function needs to grab queue_lock and use queue_flag_*()
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git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-udf-2.6
* 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-udf-2.6:
udf: Fix memory corruption when fs mounted with noadinicb option
udf: Make udf exportable
udf: fs/udf/partition.c:udf_get_pblock() mustn't be inline
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* 'for-linus' of git://git390.osdl.marist.edu/pub/scm/linux-2.6:
[S390] guest page hinting light
[S390] tty3270: fix put_char fail/success conversion.
[S390] compat ptrace cleanup
[S390] s390mach compile warning
[S390] cio: Fix parsing mechanism for blacklisted devices.
[S390] cio: Remove cio_msg kernel parameter.
[S390] s390-kvm: leave sie context on work. Removes preemption requirement
[S390] s390: Optimize user and work TIF check
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alpha:
drivers/scsi/dpt_i2o.c:1997: error: implicit declaration of function 'adpt_alpha_info'
drivers/scsi/dpt_i2o.c: At top level:
drivers/scsi/dpt_i2o.c:2032: warning: conflicting types for 'adpt_alpha_info'
drivers/scsi/dpt_i2o.c:2032: error: static declaration of 'adpt_alpha_info' follows non-static declaration
drivers/scsi/dpt_i2o.c:1997: error: previous implicit declaration of 'adpt_alpha_info' was here
Due to a copy-n-paste error in drivers/scsi/dpti.h.
Fix that up and remove some of the many daft static-declarations-in-a-header
which this driver enjoys.
Cc: Miquel van Smoorenburg <miquels@cistron.nl>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Due to a merge conflict, the sched_relax_domain_level control file was marked
as being handled by cpuset_read/write_u64, but the code to handle it was
actually in cpuset_common_file_read/write.
Since the value being written/read is in fact a signed integer, it should be
treated as such; this patch adds cpuset_read/write_s64 functions, and uses
them to handle the sched_relax_domain_level file.
With this patch, the sched_relax_domain_level can be read and written, and the
correct contents seen/updated.
Signed-off-by: Paul Menage <menage@google.com>
Cc: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Cc: Paul Jackson <pj@sgi.com>
Cc: Ingo Molnar <mingo@elte.hu>
Reviewed-by: Li Zefan <lizf@cn.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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any_slab_objects() does an atomic_read on an atomic_long_t, this
fixes it to use atomic_long_read instead.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Christoph Lameter <clameter@sgi.com>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Remember to close the files if copy_to_user() failed.
Spotted by dm.n9107@gmail.com.
Signed-off-by: Ulrich Drepper <drepper@redhat.com>
Cc: DM <dm.n9107@gmail.com>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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For e.g. proper TTY canonical support, IUTF8 termios flag has to be set as
appropriate. Linux used to not care about setting that flag for VT TTYs.
This patch fixes that by activating it according to the current mode of the
VT, and sets the default value according to the vt.default_utf8 parameter.
Signed-off-by: Samuel Thibault <samuel.thibault@ens-lyon.org>
Cc: Willy Tarreau <w@1wt.eu>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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The USB net adapter Buffalo LUA-U2-GT (0411:006e) carries a AX88178 chip.
Tested on the above HW.
Signed-off-by: Mattia Dongili <malattia@linux.it>
Acked-off-by: David Hollis <dhollis@davehollis.com>
Cc: Greg KH <greg@kroah.com>
Acked-by: Jeff Garzik <jeff@garzik.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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drivers/char/sx.c: In function 'sx_set_real_termios':
drivers/char/sx.c:973: warning: format '%u' expects type 'unsigned int', but argument 2 has type 'long unsigned int'
drivers/char/sx.c:999: warning: format '%x' expects type 'unsigned int', but argument 2 has type 'tcflag_t'
drivers/char/sx.c:1012: warning: format '%x' expects type 'unsigned int', but argument 2 has type 'tcflag_t'
sparc32 seems to use weird types for its tty things.
[ Fine by me but this is ancient debug and most of the debug in sx just
wants deleting eventually. - Alan ]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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'put_char' of 'struct tty_operations' has changed from 'void' into 'int'.
This can also shut up compiler warnings.
Cc: Jeff Dike <jdike@addtoit.com>
Signed-off-by: WANG Cong <wangcong@zeuux.org>
Acked-by: Alan Cox <alan@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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drivers/md/raid10.c:889:17: warning: Using plain integer as NULL pointer
drivers/media/video/cx18/cx18-driver.c:616:12: warning: Using plain integer as NULL pointer
sound/oss/kahlua.c:70:12: warning: Using plain integer as NULL pointer
Signed-off-by: Harvey Harrison <harvey.harrison@gmail.com>
Cc: Neil Brown <neilb@suse.de>
Cc: Mauro Carvalho Chehab <mchehab@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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The file drivers/usb/serial/iuu_phoenix.c uses "int" for flags. This can
cause hard to find bugs on some architectures. This patch converts the flags
to use "long" instead.
This bug was discovered by doing an allyesconfig make on the -rt kernel where
checks are done to ensure all flags are of size sizeof(long).
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Cc: Greg KH <greg@kroah.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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The file in drivers/rtc/rtc-ds1551.c uses "int" for flags. This can cause
hard to find bugs on some architectures. This patch converts the flags to use
"long" instead.
This bug was discovered by doing an allyesconfig make on the -rt kernel where
checks are done to ensure all flags are of size sizeof(long).
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Cc: David Brownell <david-b@pacbell.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Some files in the drivers/media/video/saa7134 directory uses "int" for flags.
This can cause hard to find bugs on some architectures. This patch converts
the flags to use "long" instead.
This bug was discovered by doing an allyesconfig make on the -rt kernel where
checks are done to ensure all flags are of size sizeof(long).
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Acked-by: Mauro Carvalho Chehab <mchehab@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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A file in the net/mac80211 directory uses "int" for flags. This can cause
hard to find bugs on some architectures. This patch converts the flags to use
"long" instead.
This bug was discovered by doing an allyesconfig make on the -rt kernel where
checks are done to ensure all flags are of size sizeof(long).
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Cc: "John W. Linville" <linville@tuxdriver.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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I noticed that
static void uart_flush_buffer(struct tty_struct *tty)
{
struct uart_state *state = tty->driver_data;
struct uart_port *port = state->port;
unsigned long flags;
/*
* This means you called this function _after_ the port was
* closed. No cookie for you.
*/
if (!state || !state->info) {
WARN_ON(1);
return;
}
is too late for checking state != NULL.
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Add a small explanation of what accessibility is.
Signed-off-by: Samuel Thibault <samuel.thibault@ens-lyon.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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The conversion between virtual and real time is as follows:
dvt = rw/w * dt <=> dt = w/rw * dvt
Since we want the fair sleeper granularity to be in real time, we actually
need to do:
dvt = - rw/w * l
This bug could be related to the regression reported by Yanmin Zhang:
| Comparing with kernel 2.6.25, sysbench+mysql(oltp, readonly) has lots
| of regressions with 2.6.26-rc1:
|
| 1) 8-core stoakley: 28%;
| 2) 16-core tigerton: 20%;
| 3) Itanium Montvale: 50%.
Reported-by: "Zhang, Yanmin" <yanmin_zhang@linux.intel.com>
Signed-off-by: Mike Galbraith <efault@gmx.de>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Yanmin Zhang reported:
| Comparing with kernel 2.6.25, AIM7 (use tmpfs) has more th
| regression under 2.6.26-rc1 on my 8-core stoakley, 16-core tigerton,
| and Itanium Montecito. Bisect located the patch below:
|
| 64ac24e738823161693bf791f87adc802cf529ff is first bad commit
| commit 64ac24e738823161693bf791f87adc802cf529ff
| Author: Matthew Wilcox <matthew@wil.cx>
| Date: Fri Mar 7 21:55:58 2008 -0500
|
| Generic semaphore implementation
|
| After I manually reverted the patch against 2.6.26-rc1 while fixing
| lots of conflicts/errors, aim7 regression became less than 2%.
i reproduced the AIM7 workload and can confirm Yanmin's findings that
-.26-rc1 regresses over .25 - by over 67% here.
Looking at the workload i found and fixed what i believe to be the real
bug causing the AIM7 regression: it was inefficient wakeup / scheduling
/ locking behavior of the new generic semaphore code, causing suboptimal
performance.
The problem comes from the following code. The new semaphore code does
this on down():
spin_lock_irqsave(&sem->lock, flags);
if (likely(sem->count > 0))
sem->count--;
else
__down(sem);
spin_unlock_irqrestore(&sem->lock, flags);
and this on up():
spin_lock_irqsave(&sem->lock, flags);
if (likely(list_empty(&sem->wait_list)))
sem->count++;
else
__up(sem);
spin_unlock_irqrestore(&sem->lock, flags);
where __up() does:
list_del(&waiter->list);
waiter->up = 1;
wake_up_process(waiter->task);
and where __down() does this in essence:
list_add_tail(&waiter.list, &sem->wait_list);
waiter.task = task;
waiter.up = 0;
for (;;) {
[...]
spin_unlock_irq(&sem->lock);
timeout = schedule_timeout(timeout);
spin_lock_irq(&sem->lock);
if (waiter.up)
return 0;
}
the fastpath looks good and obvious, but note the following property of
the contended path: if there's a task on the ->wait_list, the up() of
the current owner will "pass over" ownership to that waiting task, in a
wake-one manner, via the waiter->up flag and by removing the waiter from
the wait list.
That is all and fine in principle, but as implemented in
kernel/semaphore.c it also creates a nasty, hidden source of contention!
The contention comes from the following property of the new semaphore
code: the new owner owns the semaphore exclusively, even if it is not
running yet.
So if the old owner, even if just a few instructions later, does a
down() [lock_kernel()] again, it will be blocked and will have to wait
on the new owner to eventually be scheduled (possibly on another CPU)!
Or if another task gets to lock_kernel() sooner than the "new owner"
scheduled, it will be blocked unnecessarily and for a very long time
when there are 2000 tasks running.
I.e. the implementation of the new semaphores code does wake-one and
lock ownership in a very restrictive way - it does not allow
opportunistic re-locking of the lock at all and keeps the scheduler from
picking task order intelligently.
This kind of scheduling, with 2000 AIM7 processes running, creates awful
cross-scheduling between those 2000 tasks, causes reduced parallelism, a
throttled runqueue length and a lot of idle time. With increasing number
of CPUs it causes an exponentially worse behavior in AIM7, as the chance
for a newly woken new-owner task to actually run anytime soon is less
and less likely.
Note that it takes just a tiny bit of contention for the 'new-semaphore
catastrophy' to happen: the wakeup latencies get added to whatever small
contention there is, and quickly snowball out of control!
I believe Yanmin's findings and numbers support this analysis too.
The best fix for this problem is to use the same scheduling logic that
the kernel/mutex.c code uses: keep the wake-one behavior (that is OK and
wanted because we do not want to over-schedule), but also allow
opportunistic locking of the lock even if a wakee is already "in
flight".
The patch below implements this new logic. With this patch applied the
AIM7 regression is largely fixed on my quad testbox:
# v2.6.25 vanilla:
..................
Tasks Jobs/Min JTI Real CPU Jobs/sec/task
2000 56096.4 91 207.5 789.7 0.4675
2000 55894.4 94 208.2 792.7 0.4658
# v2.6.26-rc1-166-gc0a1811 vanilla:
...................................
Tasks Jobs/Min JTI Real CPU Jobs/sec/task
2000 33230.6 83 350.3 784.5 0.2769
2000 31778.1 86 366.3 783.6 0.2648
# v2.6.26-rc1-166-gc0a1811 + semaphore-speedup:
...............................................
Tasks Jobs/Min JTI Real CPU Jobs/sec/task
2000 55707.1 92 209.0 795.6 0.4642
2000 55704.4 96 209.0 796.0 0.4642
i.e. a 67% speedup. We are now back to within 1% of the v2.6.25
performance levels and have zero idle time during the test, as expected.
Btw., interactivity also improved dramatically with the fix - for
example console-switching became almost instantaneous during this
workload (which after all is running 2000 tasks at once!), without the
patch it was stuck for a minute at times.
There's another nice side-effect of this speedup patch, the new generic
semaphore code got even smaller:
text data bss dec hex filename
1241 0 0 1241 4d9 semaphore.o.before
1207 0 0 1207 4b7 semaphore.o.after
(because the waiter.up complication got removed.)
Longer-term we should look into using the mutex code for the generic
semaphore code as well - but i's not easy due to legacies and it's
outside of the scope of v2.6.26 and outside the scope of this patch as
well.
Bisected-by: "Zhang, Yanmin" <yanmin_zhang@linux.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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This reverts commit c3270e577c18b3d0e984c3371493205a4807db9d.
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Found these two bugs while browsing through the code. The first one is
a cut-n-paste bug, instead of disabling the clock when request_irq()
fails, it enabled it once more. The second one fixes a debug printout,
AT91_SSC_IER is write only, AT91_SSC_IMR is readable (the printed string
actually says imr).
Frank Mandarino was busy so he asked me to send these to this list.
/Patrik
Signed-off-by: Patrik Sevallius <patrik.sevallius@enea.com>
Acked-by: Frank Mandarino <fmandarino@endrelia.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
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