Change page_mkwrite to allow implementations to return with the page
locked, and also change it's callers (in page fault paths) to hold the
lock until the page is marked dirty. This allows the filesystem to have
full control of page dirtying events coming from the VM.
Rather than simply hold the page locked over the page_mkwrite call, we
call page_mkwrite with the page unlocked and allow callers to return with
it locked, so filesystems can avoid LOR conditions with page lock.
The problem with the current scheme is this: a filesystem that wants to
associate some metadata with a page as long as the page is dirty, will
perform this manipulation in its ->page_mkwrite. It currently then must
return with the page unlocked and may not hold any other locks (according
to existing page_mkwrite convention).
In this window, the VM could write out the page, clearing page-dirty. The
filesystem has no good way to detect that a dirty pte is about to be
attached, so it will happily write out the page, at which point, the
filesystem may manipulate the metadata to reflect that the page is no
longer dirty.
It is not always possible to perform the required metadata manipulation in
->set_page_dirty, because that function cannot block or fail. The
filesystem may need to allocate some data structure, for example.
And the VM cannot mark the pte dirty before page_mkwrite, because
page_mkwrite is allowed to fail, so we must not allow any window where the
page could be written to if page_mkwrite does fail.
This solution of holding the page locked over the 3 critical operations
(page_mkwrite, setting the pte dirty, and finally setting the page dirty)
closes out races nicely, preventing page cleaning for writeout being
initiated in that window. This provides the filesystem with a strong
synchronisation against the VM here.
- Sage needs this race closed for ceph filesystem.
- Trond for NFS (http://bugzilla.kernel.org/show_bug.cgi?id=12913).
- I need it for fsblock.
- I suspect other filesystems may need it too (eg. btrfs).
- I have converted buffer.c to the new locking. Even simple block allocation
under dirty pages might be susceptible to i_size changing under partial page
at the end of file (we also have a buffer.c-side problem here, but it cannot
be fixed properly without this patch).
- Other filesystems (eg. NFS, maybe btrfs) will need to change their
page_mkwrite functions themselves.
[ This also moves page_mkwrite another step closer to fault, which should
eventually allow page_mkwrite to be moved into ->fault, and thus avoiding a
filesystem calldown and page lock/unlock cycle in __do_fault. ]
[akpm@linux-foundation.org: fix derefs of NULL ->mapping]
Cc: Sage Weil <sage@newdream.net>
Cc: Trond Myklebust <trond.myklebust@fys.uio.no>
Signed-off-by: Nick Piggin <npiggin@suse.de>
Cc: Valdis Kletnieks <Valdis.Kletnieks@vt.edu>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
On a linux-next allyesconfig build:
kernel/trace/ring_buffer.c:1726:
warning: passing argument 1 of 'atomic_cmpxchg' from incompatible pointer type
linux-next/arch/s390/include/asm/atomic.h:112:
note: expected 'struct atomic_t *' but argument is of type 'struct atomic64_t *'
atomic_long_cmpxchg and atomic_long_xchg are incorrectly defined for 64
bit architectures. They should be mapped to the atomic64_* variants.
Acked-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
drivers/serial/crisv10.c:4428: error: unknown field 'read_proc' specified in initializer
Commit 0f043a81eb ("proc tty: remove struct
tty_operations::read_proc") removes the read_proc entry from struct
tty_operations.
Rework the proc handling in the CRISv10 serial driver to use proc_fops
instead.
Signed-off-by: Jesper Nilsson <jesper.nilsson@axis.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Mikael Starvik <starvik@axis.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Add Roland and Oleg as formal ptrace maintainers, they've been doing the
job for a while.
Includes the file patterns requested by Joe.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Roland McGrath <roland@redhat.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Joe Perches <joe@perches.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This is a bugfix for commit 3c776e6466
("memcg: charge swapcache to proper memcg").
Used bit of swapcache is solid under page lock, but considering
move_account, pc->mem_cgroup is not.
We need lock_page_cgroup() anyway.
Signed-off-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
I will finish school soon, so replace my student address with this one.
Signed-off-by: Florian Fainelli <florian@openwrt.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Fix an obvious incorrect return status in autofs4_mount_busy().
Signed-off-by: Ian Kent <raven@themaw.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
By the time the memory cgroup code is notified about a swapin we
already hold a reference on the fault page.
If the cgroup callback fails make sure to unlock AND release the page
reference which was taken by lookup_swap_cach(), or we leak the reference.
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Balbir Singh <balbir@linux.vnet.ibm.com>
Reviewed-by: Minchan Kim <minchan.kim@gmail.com>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
acpi_rs_get_pci_routing_table_length is not performing sufficient
validation on the package returned from _PRT. It assumes a package of
packages and fails/faults if this is not the case.
We should validate each subpackage when extracted from the parent
package, and not accept objects of the wrong type, since that will just
cause the scanning to fail (likely with a kernel oops).
This can only happen with a serious BIOS bug, and is accompanied by a
warning something like this:
ACPI Warning (nspredef-0949): \_SB_.PCI0.PEG4._PRT: Return Package type mismatch at index 0 - found Integer, expected Package [20090320]
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ecryptfs/ecryptfs-2.6:
eCryptfs: Fix min function comparison warning
ecryptfs: fix printk format warning
A regression was introduced in hg changeset 33810c734a0d, which resulted in
a kernel panic whenever the device was disconnected from USB. The call to
4l2_device_register() was overwriting the pointer for usb_set_intfdata(), so
when au0828_usb_disconnect() was called, the usb_get_intfdata() returned a
pointer to the v4l2_device instead of the au0828_dev structure.
Signed-off-by: Devin Heitmueller <dheitmueller@linuxtv.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
Two fixes for DViCO FusionHDTV DVB-T Dual Express:
* Reset correct tuner when reinitializing xc3028.
* Disable the I2C gate control to avoid locking up the I2C bus.
Tested-by: John Knops <jknops@australiaonline.net.au>
Reviewed-by: Steven Toth <stoth@linuxtv.org>
Signed-off-by: Christopher Pascoe <linuxdvb@itee.uq.edu.au>
Signed-off-by: Devin Heitmueller <dheitmueller@linuxtv.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
set_modeready flag must be set before command sent to USB in
s2255_write_config.
Signed-off-by: Dean Anderson <dean@sensoray.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
* Return actual error values as returned by the i2c subsystem, rather
than 0 or 1.
* If the registration of the second bus fails, unregister the first one
before exiting, otherwise we are leaking resources.
Signed-off-by: Jean Delvare <khali@linux-fr.org>
Acked-by: Andy Walls <awalls@radix.net>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
Currently drivers/media drivers are linked very early - directly after
base, block, misc, and mfd and before ata, scsi, ide, input, firewire,
usb, and i2c. This breaks static build of video4linux drivers, that use
generic CPU i2c adapter drivers and the v4l2-subdev subsystem, because
during video4linux probing the v4l2-subdev core requires a struct
i2c_adapter context, which cannot be satisfied before the i2c subsystem is
initialised. Moving drivers/media after drivers/i2c fixes this problem.
The best way to trigger action is by submitting a patch:-) So, let's see
what comes out of it - on the one hand I don't see any reason why media
has to be linked this early, and nobody was able to give me one yesterday
as this problem has been discussed on linux-media, OTOH, maybe indeed it
would be better to move i2c the whole way up above media, but that'd be
much bigger of a change, I think.
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Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Acked-by: Jean Delvare <khali@linux-fr.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
I lowered the kfree(t) down a couple lines and removed the superflous
"t->vdev = NULL;"
Signed-off-by: Dan Carpenter <error27@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
I moved the kfree() down a couple lines. t->vdev is going to be in freed
memory so there is no point setting it to NULL. I added a kfree(t) on a
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
selecting ALSA module breaks if !SND. Just remove select.
While here, let's fix the whitespacing at the Kconfig.
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
A late v4l2_subdev framework change accidentally sent the audio input
routing value to the external multiplexer, instead of the muxer input routing
value to the external multiplexer. This change corrects that error.
Signed-off-by: Andy Walls <awalls@radix.net>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-2.6: (24 commits)
e100: do not go D3 in shutdown unless system is powering off
netfilter: revised locking for x_tables
Bluetooth: Fix connection establishment with low security requirement
Bluetooth: Add different pairing timeout for Legacy Pairing
Bluetooth: Ensure that HCI sysfs add/del is preempt safe
net: Avoid extra wakeups of threads blocked in wait_for_packet()
net: Fix typo in net_device_ops description.
ipv4: Limit size of route cache hash table
Add reference to CAPI 2.0 standard
Documentation/isdn/INTERFACE.CAPI
update Documentation/isdn/00-INDEX
ixgbe: Fix WoL functionality for 82599 KX4 devices
veth: prevent oops caused by netdev destructor
xfrm: wrong hash value for temporary SA
forcedeth: tx timeout fix
net: Fix LL_MAX_HEADER for CONFIG_TR_MODULE
mlx4_en: Handle page allocation failure during receive
mlx4_en: Fix cleanup flow on cq activation
vlan: update vlan carrier state for admin up/down
netfilter: xt_recent: fix stack overread in compat code
...
After experimenting with kexec with the last merges after 2.6.29, I've
had some problems when probing e100. It would not read the eeprom. After
some bisects, I realized this has been like that since forever (at least
2.6.18). The problem is that shutdown is doing the same thing that
suspend does and puts the device in D3 state. I couldn't find a way to
get the device back to a sane state in the probe function. So, based on
some similar patches from Rafael J. Wysocki for e1000, e1000e, and ixgbe,
I wrote this one for e100.
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@holoscopio.com>
Acked-by: "Rafael J. Wysocki" <rjw@sisk.pl>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
The x_tables are organized with a table structure and a per-cpu copies
of the counters and rules. On older kernels there was a reader/writer
lock per table which was a performance bottleneck. In 2.6.30-rc, this
was converted to use RCU and the counters/rules which solved the performance
problems for do_table but made replacing rules much slower because of
the necessary RCU grace period.
This version uses a per-cpu set of spinlocks and counters to allow to
table processing to proceed without the cache thrashing of a global
reader lock and keeps the same performance for table updates.
Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
* 'drm-intel-next' of git://git.kernel.org/pub/scm/linux/kernel/git/anholt/drm-intel:
drm/i915: fix up error path leak in i915_cmdbuffer
drm/i915: fix unpaired i915 device mutex on entervt failure.
drm/i915: add support for G41 chipset
drm/i915: Enable ASLE if present
drm/i915: Unregister ACPI video driver when exiting
drm/i915: Register ACPI video even when not modesetting
drm/i915: fix transition to I915_TILING_NONE
drm/i915: Don't let an oops get triggered from irq_emit without dma init.
drm/i915: allow tiled front buffers on 965+
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/roland/infiniband: (21 commits)
RDMA/nes: Update iw_nes version
RDMA/nes: Fix error path in nes_accept()
RDMA/nes: Fix hang issues for large cluster dynamic connections
RDMA/nes: Increase rexmit timeout interval
RDMA/nes: Check for sequence number wrap-around
RDMA/nes: Do not set apbvt entry for loopback
RDMA/nes: Fix unused variable compile warning when INFINIBAND_NES_DEBUG=n
RDMA/nes: Fix fw_ver in /sys
RDMA/nes: Set trace length to 1 inch for SFP_D
RDMA/nes: Enable repause timer for port 1
RDMA/nes: Correct CDR loop filter setting for port 1
RDMA/nes: Modify thermo mitigation to flip SerDes1 ref clk to internal
RDMA/nes: Fix resource issues in nes_create_cq() and nes_destroy_cq()
RDMA/nes: Remove root_256()'s unused pbl_count_256 parameter
mlx4_core: Fix memory leak in mlx4_enable_msi_x()
IB/mthca: Fix timeout for INIT_HCA and a few other commands
RDMA/cxgb3: Don't zero QP attrs when moving to IDLE
RDMA/nes: Fix bugs in nes_reg_phys_mr()
RDMA/nes: Fix compiler warning at nes_verbs.c:1955
IPoIB: Disable NAPI while CQ is being drained
...
Fix this:
arch/m68k/kernel/sun3-head.S: Assembler messages:
arch/m68k/kernel/sun3-head.S:32: Error: Unknown operator -- statement `__head' ignored
Introduced by commit 6f335cab04 ("m68k:
convert to use __HEAD and HEAD_TEXT macros."), which started using
__HEAD without adding the appropriate include.
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/lrg/voltage-2.6:
regulator: Fix default constraints for fixed voltage regulators
regulator/bq24022: fix bug in is_enabled function
regulator/virtual: fix strings compare predicates
regulator core: fix double-free in regulator_register() error path
drivers/regulator: fix when type is different from REGULATOR_VOLTAGE or REGULATOR_CURRENT
unreachable code in drms_uA_update()
regulator: fix header file missing kernel-doc
* 'merge' of git://git.kernel.org/pub/scm/linux/kernel/git/paulus/powerpc:
powerpc/ps3: Fix build error on UP
powerpc/cell: Select PCI for IBM_CELL_BLADE AND CELLEB
powerpc: ppc32 needs elf_read_implies_exec()
powerpc/86xx: Add device_type entry to soc for ppc9a
powerpc/44x: Correct memory size calculation for denali-based boards
maintainers: Fix PowerPC 4xx git tree
powerpc: fix for long standing bug noticed by gcc 4.4.0
Revert "powerpc: Add support for early tlbilx opcode"
Commit edada399 broke the build on 64-bit powerpc because it moved the
__ftr_alt_* sections of a file away from the .text section, causing
link failures due to relative conditional branch targets being too far
away from the branch instructions. This happens on pretty much all
64-bit powerpc configs.
This change reverts commit edada399 while preserving the update from
the *.refok sections to .ref.text that has happened since.
Signed-off-by: Tim Abbott <tabbott@mit.edu>
Requested-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
st driver uses blk_rq_map_user() in order to just build a request out
of page frames. In this case, map_data->offset is a non zero value and
iov[0].iov_base is NULL. We need to increase nr_pages for that.
Cc: stable@kernel.org
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
hd dance around local irq and HD_IRQ enable without achieving much.
It ends up transferring data from irq handler with both local irq and
HD_IRQ disabled. The only place it actually does something is while
transferring the first block of a request which it does with HD_IRQ
disabled but local irq enabled.
Unfortunately, the dancing is horribly broken from locking POV. IRQ
and timeout handlers access block queue without grabbing the queue
lock and running the driver in SMP configuration crashes the whole
machine pretty quickly.
Remove meaningless irq enable/disable dancing and add proper locking
in issue, irq and timeout paths.
Signed-off-by: Tejun Heo <tj@kernel.org>
drivers/block/mg_disk.c: In function ‘mg_dump_status’:
drivers/block/mg_disk.c:265: warning: format ‘%ld’ expects type ‘long int’, but
argument 2 has type ‘sector_t’
[ Impact: kill build warning ]
Cc: unsik Kim <donari75@gmail.com>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
IRQ and timeout handlers call functions which expect locked queue lock
without locking it. Fix it.
While at it, convert 0s used as null pointer constant to NULLs.
[ Impact: fix locking, cleanup ]
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: unsik Kim <donari75@gmail.com>
Default voltage constraints were being provided for fixed voltage
regulator where board constraints were not provided but these constraints
used INT_MIN as the default minimum voltage which is not a valid value
since it is less than zero. Use 1uV instead.
Also set the default values we set in the constraints themselves since
otherwise the max_uV constraint we determine will not be stored in the
actual constraint strucutre and will therefore not be used.
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Liam Girdwood <lrg@slimlogic.co.uk>
This seems to be fallout from last October's regulator core rework.
It got noticed only because of recent regulator framework changes.
Signed-off-by: Philipp Zabel <philipp.zabel@gmail.com>
Signed-off-by: Liam Girdwood <lrg@slimlogic.co.uk>
Signed-off-by: Mike Rapoport <mike@compulab.co.il>
Acked-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Liam Girdwood <lrg@slimlogic.co.uk>
During regulator registration, any error after device_register() will
cause a double-free on the struct regulator_dev 'rdev'. The bug is in
drivers/regulator/core.c:regulator_register():
...
scrub:
device_unregister(&rdev->dev);
clean:
kfree(rdev); <---
rdev = ERR_PTR(ret);
goto out;
...
device_unregister() calls regulator_dev_release() which frees rdev. The
subsequent kfree corrupts memory and causes some OMAP3 systems to oops on
boot in regulator_get().
Applies against 2.6.30-rc3.
Signed-off-by: Paul Walmsley <paul@pwsan.com>
Acked-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Liam Girdwood <lrg@slimlogic.co.uk>
When regulator_desc->type is something different from REGULATOR_VOLTAGE or REGULATOR_CURRENT
the if should probably return ERR_PTR(-EINVAL)
The semantic patch that makes this change is as follows:
(http://www.emn.fr/x-info/coccinelle/)
@@ expression E; constant C; @@
(
- !E == C
+ E != C
)
Signed-off-by: Diego Liziero <diegoliz@gmail.com>
Acked-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Liam Girdwood <lrg@slimlogic.co.uk>
I removed the extra semi-colon and indented the return statement.
The unreachable code was found by smatch (http://repo.or.cz/w/smatch.git).
The patch was compile tested.
regards,
dan carpenter
Signed-off-by: Dan Carpenter <error27@gmail.com>
Acked-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Liam Girdwood <lrg@slimlogic.co.uk>
Add regulator header file missing kernel-doc:
Warning(include/linux/regulator/driver.h:117): No description found for parameter 'set_mode'
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
cc: Liam Girdwood <lrg@slimlogic.co.uk>
cc: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Liam Girdwood <lrg@slimlogic.co.uk>
The Bluetooth 2.1 specification introduced four different security modes
that can be mapped using Legacy Pairing and Simple Pairing. With the
usage of Simple Pairing it is required that all connections (except
the ones for SDP) are encrypted. So even the low security requirement
mandates an encrypted connection when using Simple Pairing. When using
Legacy Pairing (for Bluetooth 2.0 devices and older) this is not required
since it causes interoperability issues.
To support this properly the low security requirement translates into
different host controller transactions depending if Simple Pairing is
supported or not. However in case of Simple Pairing the command to
switch on encryption after a successful authentication is not triggered
for the low security mode. This patch fixes this and actually makes
the logic to differentiate between Simple Pairing and Legacy Pairing
a lot simpler.
Based on a report by Ville Tervo <ville.tervo@nokia.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
The Bluetooth stack uses a reference counting for all established ACL
links and if no user (L2CAP connection) is present, the link will be
terminated to save power. The problem part is the dedicated pairing
when using Legacy Pairing (Bluetooth 2.0 and before). At that point
no user is present and pairing attempts will be disconnected within
10 seconds or less. In previous kernel version this was not a problem
since the disconnect timeout wasn't triggered on incoming connections
for the first time. However this caused issues with broken host stacks
that kept the connections around after dedicated pairing. When the
support for Simple Pairing got added, the link establishment procedure
needed to be changed and now causes issues when using Legacy Pairing
When using Simple Pairing it is possible to do a proper reference
counting of ACL link users. With Legacy Pairing this is not possible
since the specification is unclear in some areas and too many broken
Bluetooth devices have already been deployed. So instead of trying to
deal with all the broken devices, a special pairing timeout will be
introduced that increases the timeout to 60 seconds when pairing is
triggered.
If a broken devices now puts the stack into an unforeseen state, the
worst that happens is the disconnect timeout triggers after 120 seconds
instead of 4 seconds. This allows successful pairings with legacy and
broken devices now.
Based on a report by Johan Hedberg <johan.hedberg@nokia.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
In 2.6.25 we added UDP mem accounting.
This unfortunatly added a penalty when a frame is transmitted, since
we have at TX completion time to call sock_wfree() to perform necessary
memory accounting. This calls sock_def_write_space() and utimately
scheduler if any thread is waiting on the socket.
Thread(s) waiting for an incoming frame was scheduled, then had to sleep
again as event was meaningless.
(All threads waiting on a socket are using same sk_sleep anchor)
This adds lot of extra wakeups and increases latencies, as noted
by Christoph Lameter, and slows down softirq handler.
Reference : http://marc.info/?l=linux-netdev&m=124060437012283&w=2
Fortunatly, Davide Libenzi recently added concept of keyed wakeups
into kernel, and particularly for sockets (see commit
37e5540b3c
epoll keyed wakeups: make sockets use keyed wakeups)
Davide goal was to optimize epoll, but this new wakeup infrastructure
can help non epoll users as well, if they care to setup an appropriate
handler.
This patch introduces new DEFINE_WAIT_FUNC() helper and uses it
in wait_for_packet(), so that only relevant event can wakeup a thread
blocked in this function.
Trace of function calls from bnx2 TX completion bnx2_poll_work() is :
__kfree_skb()
skb_release_head_state()
sock_wfree()
sock_def_write_space()
__wake_up_sync_key()
__wake_up_common()
receiver_wake_function() : Stops here since thread is waiting for an INPUT
Reported-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
A non-SMP version of smp_send_stop() is now included in smp.h.
Remove the unneeded definition in the PS3 smp.c.
Fixes build errors like these when CONFIG_SMP=n:
arch/powerpc/platforms/ps3/setup.c:49: error: redefinition of 'smp_send_stop'
include/linux/smp.h:125: error: previous definition of 'smp_send_stop' was here
Reported-by: Subrata Modak <subrata@linux.vnet.ibm.com>
Signed-off-by: Geoff Levand <geoffrey.levand@am.sony.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>
