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Nothing outside of the driver core should ever touch knode_bus, so
move it out of the public eye.
Cc: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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Nothing outside of the driver core should ever touch knode_driver, so
move it out of the public eye.
Cc: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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Nothing outside of the driver core should ever touch klist_children, or
knode_parent, so move them out of the public eye.
Cc: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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This is to be used to move things out of struct device that no code
outside of the driver core should ever touch.
Cc: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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This patch removes 100ms polling for driver_probe_done in
wait_for_device_probe(), and uses wait_event() instead.
Removing polling in fs initialization may lead to
a faster boot.
This patch also changes the return type of wait_for_device_done()
from int to void.
This patch is against Arjan's patch in linux-next tree.
Signed-off-by: Ming Lei <tom.leiming@gmail.com>
Acked-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Reviewed-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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If a UIO device has several memory mappings, it can be difficult for userspace
to find the right one. The situation becomes even worse if the UIO driver can
handle different versions of a card that have different numbers of mappings.
Benedikt Spranger has such cards and pointed this out to me. Thanks, Bene!
To address this problem, this patch adds "name" sysfs attributes for each
mapping. Userspace can use these to clearly identify each mapping. The name
string is optional. If a driver doesn't set it, an empty string will be
returned, so this patch won't break existing drivers.
The same problem exists for port region information, so a "name" attribute is
added there, too.
Signed-off-by: Hans J. Koch <hjk@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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Now platform_device is being widely used on SoC processors where the
peripherals are attached to the system bus, which is simple enough.
However, silicon IPs for these SoCs are usually shared heavily across
a family of processors, even products from different companies. This
makes the original simple driver name based matching insufficient, or
simply not straight-forward.
Introduce a module id table for platform devices, and makes it clear
that a platform driver is able to support some shared IP and handle
slight differences across different platforms (by 'driver_data').
Module alias is handled automatically when a MODULE_DEVICE_TABLE()
is defined.
To not disturb the current platform drivers too much, the matched id
entry is recorded and can be retrieved by platform_get_device_id().
Signed-off-by: Eric Miao <eric.miao@marvell.com>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Cc: Ben Dooks <ben-linux@fluff.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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Now that all users of bus_id is gone, we can remove it from struct
device.
Signed-off-by: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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Cc: inaky.perez-gonzalez@intel.com
Cc: linux-wimax@intel.com
Acked-by: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Kay Sievers <kay.sievers@vrfy.org>
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* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-2.6: (32 commits)
ucc_geth: Fix oops when using fixed-link support
dm9000: locking bugfix
net: update dnet.c for bus_id removal
dnet: DNET should depend on HAS_IOMEM
dca: add missing copyright/license headers
nl80211: Check that function pointer != NULL before using it
sungem: missing net_device_ops
be2net: fix to restore vlan ids into BE2 during a IF DOWN->UP cycle
be2net: replenish when posting to rx-queue is starved in out of mem conditions
bas_gigaset: correctly allocate USB interrupt transfer buffer
smsc911x: reset last known duplex and carrier on open
sh_eth: Fix mistake of the address of SH7763
sh_eth: Change handling of IRQ
netns: oops in ip[6]_frag_reasm incrementing stats
net: kfree(napi->skb) => kfree_skb
net: fix sctp breakage
ipv6: fix display of local and remote sit endpoints
net: Document /proc/sys/net/core/netdev_budget
tulip: fix crash on iface up with shirq debug
virtio_net: Make virtio_net support carrier detection
...
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In two dca files copyright and license headers are missing.
This patch adds them there.
Signed-off-by: Maciej Sosnowski <maciej.sosnowski@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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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>
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* master.kernel.org:/home/rmk/linux-2.6-arm: (23 commits)
[ARM] Fix virtual to physical translation macro corner cases
[ARM] update mach-types
[ARM] 5421/1: ftrace: fix crash due to tracing of __naked functions
MX1 fix include
[ARM] 5419/1: ep93xx: fix build warnings about struct i2c_board_info
[ARM] 5418/1: restore lr before leaving mcount
ARM: OMAP: board-omap3beagle: set i2c-3 to 100kHz
ARM: OMAP: Allow I2C bus driver to be compiled as a module
ARM: OMAP: sched_clock() corrected
ARM: OMAP: Fix compile error if pm.h is included
[ARM] orion5x: pass dram mbus data to xor driver
[ARM] S3C64XX: Fix s3c64xx_setrate_clksrc
[ARM] S3C64XX: sparse warnings in arch/arm/plat-s3c64xx/irq.c
[ARM] S3C64XX: sparse warnings in arch/arm/plat-s3c64xx/s3c6400-clock.c
[ARM] S3C64XX: Fix USB host clock mux list
[ARM] S3C64XX: Fix name of USB host clock.
[ARM] S3C64XX: Rename IRQ_UHOST to IRQ_USBH
[ARM] S3C64XX: Do gpiolib configuration earlier
[ARM] S3C64XX: Staticise s3c64xx_init_irq_eint()
[ARM] SMDK6410: Declare iodesc table static
...
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* 'for-linus' of git://git.kernel.dk/linux-2.6-block:
Fix Xilinx SystemACE driver to handle empty CF slot
block: fix memory leak in bio_clone()
block: Add gfp_mask parameter to bio_integrity_clone()
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Stricter gfp_mask might be required for clone allocation.
For example, request-based dm may clone bio in interrupt context
so it has to use GFP_ATOMIC.
Signed-off-by: Kiyoshi Ueda <k-ueda@ct.jp.nec.com>
Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com>
Acked-by: Martin K. Petersen <martin.petersen@oracle.com>
Cc: Alasdair G Kergon <agk@redhat.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
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* 'bugfixes' of git://git.linux-nfs.org/projects/trondmy/nfs-2.6:
NFS: Fix the fix to Bugzilla #11061, when IPv6 isn't defined...
SUNRPC: xprt_connect() don't abort the task if the transport isn't bound
SUNRPC: Fix an Oops due to socket not set up yet...
Bug 11061, NFS mounts dropped
NFS: Handle -ESTALE error in access()
NLM: Fix GRANT callback address comparison when IPv6 is enabled
NLM: Shrink the IPv4-only version of nlm_cmp_addr()
NFSv3: Fix posix ACL code
NFS: Fix misparsing of nfsv4 fs_locations attribute (take 2)
SUNRPC: Tighten up the task locking rules in __rpc_execute()
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dma_map_sg could return a value different to 'nents' argument of
dma_map_sg so the ide stack needs to save it for the later usage
(e.g. for_each_sg).
The ide stack also needs to save the original sg_nents value for
pci_unmap_sg.
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
[bart: backport to Linus' tree]
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
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This is a fix for the following crash observed in 2.6.29-rc3:
http://lkml.org/lkml/2009/1/29/150
On ARM it doesn't make sense to trace a naked function because then
mcount is called without stack and frame pointer being set up and there
is no chance to restore the lr register to the value before mcount was
called.
Reported-by: Matthias Kaehlcke <matthias@kaehlcke.net>
Tested-by: Matthias Kaehlcke <matthias@kaehlcke.net>
Cc: Abhishek Sagar <sagar.abhishek@gmail.com>
Cc: Steven Rostedt <rostedt@home.goodmis.org>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
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This allows us to change the representation (to a dangling bitmap or
cpumask_var_t) without breaking all the callers: they can use
mm_cpumask() now and won't see a difference as the changes roll into
linux-next.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
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This allows us to change the representation (to a dangling bitmap or
cpumask_var_t) without breaking all the callers: they can use
tsk_cpumask() now and won't see a difference as the changes roll into
linux-next.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
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Clean up/micro-optimatization: Make the AF_INET-only version of
nlm_cmp_addr() smaller. This matches the style of
nlm_privileged_requester(), and makes the AF_INET-only version of
nlm_cmp_addr() nearly the same size as it was before IPv6 support.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
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Fix a memory leak due to allocation in the XDR layer. In cases where the
RPC call needs to be retransmitted, we end up allocating new pages without
clearing the old ones. Fix this by moving the allocation into
nfs3_proc_setacls().
Also fix an issue discovered by Kevin Rudd, whereby the amount of memory
reserved for the acls in the xdr_buf->head was miscalculated, and causing
corruption.
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
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git://git.kernel.org/pub/scm/linux/kernel/git/davej/cpufreq
* 'fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/davej/cpufreq:
[CPUFREQ] Add p4-clockmod sysfs-ui removal to feature-removal schedule.
Revert "[CPUFREQ] Disable sysfs ui for p4-clockmod."
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This reverts commit e088e4c9cdb618675874becb91b2fd581ee707e6.
Removing the sysfs interface for p4-clockmod was flagged as a
regression in bug 12826.
Course of action:
- Find out the remaining causes of overheating, and fix them
if possible. ACPI should be doing the right thing automatically.
If it isn't, we need to fix that.
- mark p4-clockmod ui as deprecated
- try again with the removal in six months.
It's not really feasible to printk about the deprecation, because
it needs to happen at all the sysfs entry points, which means adding
a lot of strcmp("p4-clockmod".. calls to the core, which.. bleuch.
Signed-off-by: Dave Jones <davej@redhat.com>
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* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-2.6: (29 commits)
p54: fix race condition in memory management
cfg80211: test before subtraction on unsigned
iwlwifi: fix error flow in iwl*_pci_probe
rt2x00 : more devices to rt73usb.c
rt2x00 : more devices to rt2500usb.c
bonding: Fix device passed into ->ndo_neigh_setup().
vlan: Fix vlan-in-vlan crashes.
net: Fix missing dev->neigh_setup in register_netdevice().
tmspci: fix request_irq race
pkt_sched: act_police: Fix a rate estimator test.
tg3: Fix 5906 link problems
SCTP: change sctp_ctl_sock_init() to try IPv4 if IPv6 fails
IPv6: add "disable" module parameter support to ipv6.ko
sungem: another error printed one too early
aoe: error printed 1 too early
net pcmcia: worklimit reaches -1
net: more timeouts that reach -1
net: fix tokenring license
dm9601: new vendor/product IDs
netlink: invert error code in netlink_set_err()
...
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git://git.kernel.org/pub/scm/linux/kernel/git/djbw/async_tx
* 'fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/djbw/async_tx:
dmatest: fix use after free in dmatest_exit
ipu_idmac: fix spinlock type
iop-adma, mv_xor: fix mem leak on self-test setup failure
fsldma: fix off by one in dma_halt
I/OAT: fail self-test if callback test reaches timeout
I/OAT: update driver version and copyright dates
I/OAT: list usage cleanup
I/OAT: set tcp_dma_copybreak to 256k for I/OAT ver.3
I/OAT: cancel watchdog before dma remove
I/OAT: fail initialization on zero channels detection
I/OAT: do not set DCACTRL_CMPL_WRITE_ENABLE for I/OAT ver.3
I/OAT: add verification for proper APICID_TAG_MAP setting by BIOS
dmaengine: update kerneldoc
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* git://git.kernel.org/pub/scm/linux/kernel/git/bart/ide-2.6:
ata: add CFA specific identify data words
remove stale comment from <linux/hdreg.h>
AT91: initialize Compact Flash on AT91SAM9263 cpu
ide: add at91_ide driver
ide: allow to wrap interrupt handler
ide-iops: fix odd-length ATAPI PIO transfers
ide: NULL noise: drivers/ide/ide-*.c
ide: expiry() returns int, negative expiry() return values won't be noticed
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git://git.kernel.org/pub/scm/linux/kernel/git/jgarzik/libata-dev
* 'upstream-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jgarzik/libata-dev:
libata: Don't trust current capacity values in identify words 57-58
libata: make sure port is thawed when skipping resets
sata_nv: fix module parameter description
ahci: Add the Device IDs for MCP89 and remove IDs of MCP7B to/from ahci.c
libata: don't use on-stack sense buffer
libata: align ap->sector_buf
libata: fix dma_unmap_sg misuse
libata: change drive ready wait after hard reset to 5s
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git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input:
Input: serio - fix protocol number for TouchIT213
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Protocol 0x37 has been reserved for iNexio devices and Sahara
was supposed to get 0x38.
Reported-by: Claudio Nieder <private@claudio.ch>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
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Declare CFA specific identify data words 162 and 163 for future use.
Signed-off-by: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>
[bart: update patch summary/description]
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
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HDIO_GET_IDENTITY returns 256 words currently.
Noticed by Norman Diamond.
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
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Signed-off-by: Stanislaw Gruszka <stf_xl@wp.pl>
Cc: Andrew Victor <linux@maxim.org.za>
[bart: minor checkpatch.pl / CodingStyle fixups]
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
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ap->sector_buf is used as DMA target and should at least be aligned on
cacheline. This caused problems on some embedded machines.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>
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libata passes the returned value of dma_map_sg() to
dma_unmap_sg(),which is the misuse of dma_unmap_sg().
DMA-mapping.txt says:
To unmap a scatterlist, just call:
pci_unmap_sg(pdev, sglist, nents, direction);
Again, make sure DMA activity has already finished.
PLEASE NOTE: The 'nents' argument to the pci_unmap_sg call must be
the _same_ one you passed into the pci_map_sg call,
it should _NOT_ be the 'count' value _returned_ from the
pci_map_sg call.
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Acked-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>
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This fixes problems during resume with drives that take longer than 1s to
be ready. The ATA-6 spec appears to allow 5 seconds for a drive to be
ready.
On one affected system, this patch changes "PM: resume devices took..."
message from 17 seconds to 4 seconds, and gets rid of a lot of ugly
timeout/error messages.
Without this patch, the libata code moves on after 1s, tries to send a
soft reset (which the drive doesn't see because it isn't ready) which also
times out, then an IDENTIFY command is sent to the drive which times out,
and finally the error handler will try to send another hard reset which
will finally get things working.
Signed-off-by: Stuart Hayes <stuart_hayes@dell.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>
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As analyzed by Patrick McHardy, vlan needs to reset it's
netdev_ops pointer in it's ->init() function but this
leaves the compat method pointers stale.
Add a netdev_resync_ops() and call it from the vlan code.
Any other driver which changes ->netdev_ops after register_netdevice()
will need to call this new function after doing so too.
With help from Patrick McHardy.
Tested-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'sched-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
sched: don't allow setuid to succeed if the user does not have rt bandwidth
sched_rt: don't start timer when rt bandwidth disabled
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'core-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
rcu: Teach RCU that idle task is not quiscent state at boot
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'x86-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
fix warning in io_mapping_map_wc()
x86: i915 needs pgprot_writecombine() and is_io_mapping_possible()
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Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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The DCB netlink interface is required for building the userspace tools
available at e1000.sourceforge.net
Signed-off-by: Chris Leech <christopher.leech@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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1) add an include for <linux/types.h>
2) change dcbmsg.dcb_family from unsigned char to __u8 to be more
consistent with use of kernel types
Signed-off-by: Chris Leech <christopher.leech@intel.com>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'x86-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
x86: enable DMAR by default
xen: disable interrupts early, as start_kernel expects
gpu/drm, x86, PAT: io_mapping_create_wc and resource_size_t
gpu/drm, x86, PAT: Handle io_mapping_create_wc() errors in a clean way
x86, Voyager: fix compile by lifting the degeneracy of phys_cpu_present_map
x86, doc: fix references to Documentation/x86/i386/boot.txt
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free_uid() and free_user_ns() are corecursive when CONFIG_USER_SCHED=n,
but free_user_ns() is called from free_uid() by way of uid_hash_remove(),
which requires uidhash_lock to be held. free_user_ns() then calls
free_uid() to complete the destruction.
Fix this by deferring the destruction of the user_namespace.
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Impact: fix hung task with certain (non-default) rt-limit settings
Corey Hickey reported that on using setuid to change the uid of a
rt process, the process would be unkillable and not be running.
This is because there was no rt runtime for that user group. Add
in a check to see if a user can attach an rt task to its task group.
On failure, return EINVAL, which is also returned in
CONFIG_CGROUP_SCHED.
Reported-by: Corey Hickey <bugfood-ml@fatooh.org>
Signed-off-by: Dhaval Giani <dhaval@linux.vnet.ibm.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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blk_recalc_rq_segments() requires a request structure passed in, which
we don't have from blk_recount_segments(). So the latter allocates one on
the stack, using > 400 bytes of stack for that. This can cause us to spill
over one page of stack from ext4 at least:
0) 4560 400 blk_recount_segments+0x43/0x62
1) 4160 32 bio_phys_segments+0x1c/0x24
2) 4128 32 blk_rq_bio_prep+0x2a/0xf9
3) 4096 32 init_request_from_bio+0xf9/0xfe
4) 4064 112 __make_request+0x33c/0x3f6
5) 3952 144 generic_make_request+0x2d1/0x321
6) 3808 64 submit_bio+0xb9/0xc3
7) 3744 48 submit_bh+0xea/0x10e
8) 3696 368 ext4_mb_init_cache+0x257/0xa6a [ext4]
9) 3328 288 ext4_mb_regular_allocator+0x421/0xcd9 [ext4]
10) 3040 160 ext4_mb_new_blocks+0x211/0x4b4 [ext4]
11) 2880 336 ext4_ext_get_blocks+0xb61/0xd45 [ext4]
12) 2544 96 ext4_get_blocks_wrap+0xf2/0x200 [ext4]
13) 2448 80 ext4_da_get_block_write+0x6e/0x16b [ext4]
14) 2368 352 mpage_da_map_blocks+0x7e/0x4b3 [ext4]
15) 2016 352 ext4_da_writepages+0x2ce/0x43c [ext4]
16) 1664 32 do_writepages+0x2d/0x3c
17) 1632 144 __writeback_single_inode+0x162/0x2cd
18) 1488 96 generic_sync_sb_inodes+0x1e3/0x32b
19) 1392 16 sync_sb_inodes+0xe/0x10
20) 1376 48 writeback_inodes+0x69/0xb3
21) 1328 208 balance_dirty_pages_ratelimited_nr+0x187/0x2f9
22) 1120 224 generic_file_buffered_write+0x1d4/0x2c4
23) 896 176 __generic_file_aio_write_nolock+0x35f/0x393
24) 720 80 generic_file_aio_write+0x6c/0xc8
25) 640 80 ext4_file_write+0xa9/0x137 [ext4]
26) 560 320 do_sync_write+0xf0/0x137
27) 240 48 vfs_write+0xb3/0x13c
28) 192 64 sys_write+0x4c/0x74
29) 128 128 system_call_fastpath+0x16/0x1b
Split the segment counting out into a __blk_recalc_rq_segments() helper
to avoid allocating an onstack request just for checking the physical
segment count.
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
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This patch fixes a bug located by Vegard Nossum with the aid of
kmemcheck, updated based on review comments from Nick Piggin,
Ingo Molnar, and Andrew Morton. And cleans up the variable-name
and function-name language. ;-)
The boot CPU runs in the context of its idle thread during boot-up.
During this time, idle_cpu(0) will always return nonzero, which will
fool Classic and Hierarchical RCU into deciding that a large chunk of
the boot-up sequence is a big long quiescent state. This in turn causes
RCU to prematurely end grace periods during this time.
This patch changes the rcutree.c and rcuclassic.c rcu_check_callbacks()
function to ignore the idle task as a quiescent state until the
system has started up the scheduler in rest_init(), introducing a
new non-API function rcu_idle_now_means_idle() to inform RCU of this
transition. RCU maintains an internal rcu_idle_cpu_truthful variable
to track this state, which is then used by rcu_check_callback() to
determine if it should believe idle_cpu().
Because this patch has the effect of disallowing RCU grace periods
during long stretches of the boot-up sequence, this patch also introduces
Josh Triplett's UP-only optimization that makes synchronize_rcu() be a
no-op if num_online_cpus() returns 1. This allows boot-time code that
calls synchronize_rcu() to proceed normally. Note, however, that RCU
callbacks registered by call_rcu() will likely queue up until later in
the boot sequence. Although rcuclassic and rcutree can also use this
same optimization after boot completes, rcupreempt must restrict its
use of this optimization to the portion of the boot sequence before the
scheduler starts up, given that an rcupreempt RCU read-side critical
section may be preeempted.
In addition, this patch takes Nick Piggin's suggestion to make the
system_state global variable be __read_mostly.
Changes since v4:
o Changes the name of the introduced function and variable to
be less emotional. ;-)
Changes since v3:
o WARN_ON(nr_context_switches() > 0) to verify that RCU
switches out of boot-time mode before the first context
switch, as suggested by Nick Piggin.
Changes since v2:
o Created rcu_blocking_is_gp() internal-to-RCU API that
determines whether a call to synchronize_rcu() is itself
a grace period.
o The definition of rcu_blocking_is_gp() for rcuclassic and
rcutree checks to see if but a single CPU is online.
o The definition of rcu_blocking_is_gp() for rcupreempt
checks to see both if but a single CPU is online and if
the system is still in early boot.
This allows rcupreempt to again work correctly if running
on a single CPU after booting is complete.
o Added check to rcupreempt's synchronize_sched() for there
being but one online CPU.
Tested all three variants both SMP and !SMP, booted fine, passed a short
rcutorture test on both x86 and Power.
Located-by: Vegard Nossum <vegard.nossum@gmail.com>
Tested-by: Vegard Nossum <vegard.nossum@gmail.com>
Tested-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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