NFSv4: Document the recover_lost_locks kernel parameter
Rename the new 'recover_locks' kernel parameter to 'recover_lost_locks'
and change the default to 'false'. Document why in
Documentation/kernel-parameters.txt
Move the 'recover_lost_locks' kernel parameter to fs/nfs/super.c to
make it easy to backport to kernels prior to 3.6.x, which don't have
a separate NFSv4 module.
NFSv4: Don't try to recover NFSv4 locks when they are lost.
When an NFSv4 client loses contact with the server it can lose any
locks that it holds.
Currently when it reconnects to the server it simply tries to reclaim
those locks. This might succeed even though some other client has
held and released a lock in the mean time. So the first client might
think the file is unchanged, but it isn't. This isn't good.
If, when recovery happens, the locks cannot be claimed because some
other client still holds the lock, then we get a message in the kernel
logs, but the client can still write. So two clients can both think
they have a lock and can both write at the same time. This is equally
not good.
There was a patch a while ago
http://comments.gmane.org/gmane.linux.nfs/41917
which tried to address some of this, but it didn't seem to go
anywhere. That patch would also send a signal to the process. That
might be useful but for now this patch just causes writes to fail.
For NFSv4 (unlike v2/v3) there is a strong link between the lock and
the write request so we can fairly easily fail any IO of the lock is
gone. While some applications might not expect this, it is still
safer than allowing the write to succeed.
Because this is a fairly big change in behaviour a module parameter,
"recover_locks", is introduced which defaults to true (the current
behaviour) but can be set to "false" to tell the client not to try to
recover things that were lost.
Chuck Lever [Wed, 4 Sep 2013 16:26:05 +0000 (12:26 -0400)]
NFS: Fix warning introduced by NFSv4.0 transport blocking patches
When CONFIG_NFS_V4_1 is not enabled, gcc emits this warning:
linux/fs/nfs/nfs4state.c:255:12: warning:
‘nfs4_begin_drain_session’ defined but not used [-Wunused-function]
static int nfs4_begin_drain_session(struct nfs_client *clp)
^
Eventually NFSv4.0 migration recovery will invoke this function, but
that has not yet been merged. Hide nfs4_begin_drain_session()
behind CONFIG_NFS_V4_1 for now.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Chuck Lever [Wed, 4 Sep 2013 16:26:03 +0000 (12:26 -0400)]
When CONFIG_NFS_V4_1 is not enabled, "make C=2" emits this warning:
linux/fs/nfs/nfs4session.c:337:6: warning:
symbol 'nfs41_set_target_slotid' was not declared. Should it be static?
Move nfs41_set_target_slotid() and nfs41_update_target_slotid() back
behind CONFIG_NFS_V4_1, since, in the final revision of this work,
they are used only in NFSv4.1 and later.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Chuck Lever [Fri, 9 Aug 2013 16:49:29 +0000 (12:49 -0400)]
NFS: Enable nfs4_setup_sequence() for DELEGRETURN
When CONFIG_NFS_V4_1 is disabled, the calls to nfs4_setup_sequence()
and nfs4_sequence_done() are compiled out for the DELEGRETURN
operation. To allow NFSv4.0 transport blocking to work for
DELEGRETURN, these call sites have to be present all the time.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Chuck Lever [Fri, 9 Aug 2013 16:48:44 +0000 (12:48 -0400)]
NFS: Enable slot table helpers for NFSv4.0
I'd like to re-use NFSv4.1's slot table machinery for NFSv4.0
transport blocking. Re-organize some of nfs4session.c so the slot
table code is built even when NFS_V4_1 is disabled.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Chuck Lever [Fri, 9 Aug 2013 16:48:09 +0000 (12:48 -0400)]
NFS: Clean up nfs4_setup_sequence()
Clean up: Both the NFSv4.0 and NFSv4.1 version of
nfs4_setup_sequence() are used only in fs/nfs/nfs4proc.c. No need
to keep global header declarations for either version.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Chuck Lever [Fri, 9 Aug 2013 16:47:51 +0000 (12:47 -0400)]
NFS: When displaying session slot numbers, use "%u" consistently
Clean up, since slot and sequence numbers are all unsigned anyway.
Among other things, squelch compiler warnings:
linux/fs/nfs/nfs4proc.c: In function ‘nfs4_setup_sequence’:
linux/fs/nfs/nfs4proc.c:703:2: warning: signed and unsigned type in
conditional expression [-Wsign-compare]
and
linux/fs/nfs/nfs4session.c: In function ‘nfs4_alloc_slot’:
linux/fs/nfs/nfs4session.c:151:31: warning: signed and unsigned type in
conditional expression [-Wsign-compare]
Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
then the asynchronous nature of the sillyrename operation means that
we can end up getting EBUSY for the rmdir() in the above test. Fix
that by ensuring that we wait for any in-progress sillyrenames
before sending the rmdir() to the server.
1) the nfs_client's rpc_client was using KRB5i/p (now tried by default)
2) the current user doesn't have valid kerberos credentials
This situation is quite common - as of now a sec=sys mount would use
krb5i for the nfs_client's rpc_client and a user would hardly be faulted
for not having run kinit.
The solution is to use the machine cred when trying to use an integrity
protected auth flavor for SECINFO.
Older servers may not support using the machine cred or an integrity
protected auth flavor for SECINFO in every circumstance, so we fall back
to using the user's cred and the filesystem's auth flavor in this case.
We run into another problem when running against linux nfs servers -
they return NFS4ERR_WRONGSEC when using integrity auth flavor (unless the
mount is also that flavor) even though that is not a valid error for
SECINFO*. Even though it's against spec, handle WRONGSEC errors on SECINFO
by falling back to using the user cred and the filesystem's auth flavor.
Andy Adamson [Wed, 14 Aug 2013 15:59:17 +0000 (11:59 -0400)]
SUNRPC refactor rpcauth_checkverf error returns
Most of the time an error from the credops crvalidate function means the
server has sent us a garbage verifier. The gss_validate function is the
exception where there is an -EACCES case if the user GSS_context on the client
has expired.
Signed-off-by: Andy Adamson <andros@netapp.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Andy Adamson [Wed, 14 Aug 2013 15:59:16 +0000 (11:59 -0400)]
NFS avoid expired credential keys for buffered writes
We must avoid buffering a WRITE that is using a credential key (e.g. a GSS
context key) that is about to expire or has expired. We currently will
paint ourselves into a corner by returning success to the applciation
for such a buffered WRITE, only to discover that we do not have permission when
we attempt to flush the WRITE (and potentially associated COMMIT) to disk.
Use the RPC layer credential key timeout and expire routines which use a
a watermark, gss_key_expire_timeo. We test the key in nfs_file_write.
If a WRITE is using a credential with a key that will expire within
watermark seconds, flush the inode in nfs_write_end and send only
NFS_FILE_SYNC WRITEs by adding nfs_ctx_key_to_expire to nfs_need_sync_write.
Note that this results in single page NFS_FILE_SYNC WRITEs.
Signed-off-by: Andy Adamson <andros@netapp.com>
[Trond: removed a pr_warn_ratelimited() for now] Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Andy Adamson [Wed, 14 Aug 2013 15:59:15 +0000 (11:59 -0400)]
SUNRPC new rpc_credops to test credential expiry
This patch provides the RPC layer helper functions to allow NFS to manage
data in the face of expired credentials - such as avoiding buffered WRITEs
and COMMITs when the gss context will expire before the WRITEs are flushed
and COMMITs are sent.
These helper functions enable checking the expiration of an underlying
credential key for a generic rpc credential, e.g. the gss_cred gss context
gc_expiry which for Kerberos is set to the remaining TGT lifetime.
A new rpc_authops key_timeout is only defined for the generic auth.
A new rpc_credops crkey_to_expire is only defined for the generic cred.
A new rpc_credops crkey_timeout is only defined for the gss cred.
Set a credential key expiry watermark, RPC_KEY_EXPIRE_TIMEO set to 240 seconds
as a default and can be set via a module parameter as we need to ensure there
is time for any dirty data to be flushed.
If key_timeout is called on a credential with an underlying credential key that
will expire within watermark seconds, we set the RPC_CRED_KEY_EXPIRE_SOON
flag in the generic_cred acred so that the NFS layer can clean up prior to
key expiration.
Checking a generic credential's underlying credential involves a cred lookup.
To avoid this lookup in the normal case when the underlying credential has
a key that is valid (before the watermark), a notify flag is set in
the generic credential the first time the key_timeout is called. The
generic credential then stops checking the underlying credential key expiry, and
the underlying credential (gss_cred) match routine then checks the key
expiration upon each normal use and sets a flag in the associated generic
credential only when the key expiration is within the watermark.
This in turn signals the generic credential key_timeout to perform the extra
credential lookup thereafter.
Signed-off-by: Andy Adamson <andros@netapp.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Andy Adamson [Wed, 14 Aug 2013 15:59:13 +0000 (11:59 -0400)]
SUNRPC: don't map EKEYEXPIRED to EACCES in call_refreshresult
The NFS layer needs to know when a key has expired.
This change also returns -EKEYEXPIRED to the application, and the informative
"Key has expired" error message is displayed. The user then knows that
credential renewal is required.
Signed-off-by: Andy Adamson <andros@netapp.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
SUNRPC: rpcauth_create needs to know about rpc_clnt clone status
Ensure that we set rpc_clnt->cl_parent before calling rpc_client_register
so that rpcauth_create can find any existing RPCSEC_GSS caches for this
transport.
Trond Myklebust [Mon, 26 Aug 2013 19:38:11 +0000 (15:38 -0400)]
SUNRPC: Add a framework to clean up management of rpc_pipefs directories
The current system requires everyone to set up notifiers, manage directory
locking, etc.
What we really want to do is have the rpc_client create its directory,
and then create all the entries.
This patch will allow the RPCSEC_GSS and NFS code to register all the
objects that they want to have appear in the directory, and then have
the sunrpc code call them back to actually create/destroy their pipefs
dentries when the rpc_client creates/destroys the parent.
Trond Myklebust [Mon, 26 Aug 2013 20:05:11 +0000 (16:05 -0400)]
RPCSEC_GSS: Fix an Oopsable condition when creating/destroying pipefs objects
If an error condition occurs on rpc_pipefs creation, or the user mounts
rpc_pipefs and then unmounts it, then the dentries in struct gss_auth
need to be reset to NULL so that a second call to gss_pipes_dentries_destroy
doesn't try to free them again.
Trond Myklebust [Mon, 26 Aug 2013 23:23:04 +0000 (19:23 -0400)]
SUNRPC: Replace clnt->cl_principal
The clnt->cl_principal is being used exclusively to store the service
target name for RPCSEC_GSS/krb5 callbacks. Replace it with something that
is stored only in the RPCSEC_GSS-specific code.
After reclaiming state that was lost, the NFS client tries to reclaim
any locks, and then checks that each one has NFS_LOCK_INITIALIZED set
(which means that the server has confirmed the lock).
However if the client holds a delegation, nfs_reclaim_locks() simply aborts
(or more accurately it called nfs_lock_reclaim() and that returns without
doing anything).
This is because when a delegation is held, the server doesn't need to
know about locks.
So if a delegation is held, NFS_LOCK_INITIALIZED is not expected, and
its absence is certainly not an error.
So don't print the warnings if NFS_DELGATED_STATE is set.
Trond Myklebust [Tue, 20 Aug 2013 16:29:27 +0000 (12:29 -0400)]
NFS: Remove the NFSv4 "open optimisation" from nfs_permission
Ever since commit 6168f62cb (Add ACCESS operation to OPEN compound)
the NFSv4 atomic open has primed the access cache, and so nfs_permission
will no longer do an RPC call on the wire.
Andy Adamson [Mon, 22 Jul 2013 22:41:23 +0000 (18:41 -0400)]
NFSv4.1 Increase NFS4_DEF_SLOT_TABLE_SIZE
Increase NFS4_DEF_SLOT_TABLE_SIZE which is used as the client ca_maxreequests
value in CREATE_SESSION. Current non-dynamic session slot server
implementations use the client ca_maxrequests as a maximum slot number: 64
session slots can handle most workloads.
Signed-off-by: Andy Adamson <andros@netapp.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Chuck Lever [Wed, 24 Jul 2013 16:28:37 +0000 (12:28 -0400)]
NFS: Never use user credentials for lease renewal
Never try to use a non-UID 0 user credential for lease management,
as that credential can change out from under us. The server will
block NFSv4 lease recovery with NFS4ERR_CLID_INUSE.
Since the mechanism to acquire a credential for lease management
is now the same for all minor versions, replace the minor version-
specific callout with a single function.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Chuck Lever [Wed, 24 Jul 2013 16:28:28 +0000 (12:28 -0400)]
NFS: Use root's credential for lease management when keytab is missing
Commit 05f4c350 "NFS: Discover NFSv4 server trunking when mounting"
Fri Sep 14 17:24:32 2012 introduced Uniform Client String support,
which forces our NFS client to establish a client ID immediately
during a mount operation rather than waiting until a user wants to
open a file.
Normally machine credentials (eg. from a keytab) are used to perform
a mount operation that is protected by Kerberos. Before 05fc350,
SETCLIENTID used a machine credential, or fell back to a regular
user's credential if no keytab is available.
On clients that don't have a keytab, performing SETCLIENTID early
means there's no user credential to fall back on, since no regular
user has kinit'd yet. 05f4c350 seems to have broken the ability
to mount with sec=krb5 on clients that don't have a keytab in
kernels 3.7 - 3.10.
To address this regression, commit 4edaa308 (NFS: Use "krb5i" to
establish NFSv4 state whenever possible), Sat Mar 16 15:56:20 2013,
was merged in 3.10. This commit forces the NFS client to fall back
to AUTH_SYS for lease management operations if no keytab is
available.
Neil Brown noticed that, since root is required to kinit to do a
sec=krb5 mount when a client doesn't have a keytab, we can try to
use root's Kerberos credential before AUTH_SYS.
Now, when determining a principal and flavor to use for lease
management, the NFS client tries in this order:
1. Flavor: AUTH_GSS, krb5i
Principal: service principal (via keytab)
2. Flavor: AUTH_GSS, krb5i
Principal: user principal established for UID 0 (via kinit)
3. Flavor: AUTH_SYS
Principal: UID 0 / GID 0
Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Jeff Layton [Fri, 2 Aug 2013 15:39:32 +0000 (11:39 -0400)]
nfs: verify open flags before allowing an atomic open
Currently, you can open a NFSv4 file with O_APPEND|O_DIRECT, but cannot
fcntl(F_SETFL,...) with those flags. This flag combination is explicitly
forbidden on NFSv3 opens, and it seems like it should also be on NFSv4.
Reported-by: Chao Ye <cye@redhat.com> Signed-off-by: Jeff Layton <jlayton@redhat.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
NFSv4: Fix nfs4_init_uniform_client_string for net namespaces
Commit 6f2ea7f2a (NFS: Add nfs4_unique_id boot parameter) introduces a
boot parameter that allows client administrators to set a string
identifier for use by the EXCHANGE_ID and SETCLIENTID arguments in order
to make them more globally unique.
Unfortunately, that uniquifier is no longer globally unique in the presence
of net namespaces, since each container expects to be able to set up their
own lease when mounting a new NFSv4/4.1 partition.
The fix is to add back in the container-specific hostname in addition to
the unique id.
Cc: Chuck Lever <chuck.lever@oracle.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Chuck Lever [Fri, 12 Jul 2013 16:31:45 +0000 (12:31 -0400)]
NFS: Fix return type of nfs4_end_drain_session() stub
Clean up: when NFSv4.1 support is compiled out,
nfs4_end_drain_session() becomes a stub. Make the synopsis of the
stub match the synopsis of the real version of the function.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
NFSv4: encode_attrs should not backfill the bitmap and attribute length
The attribute length is already calculated in advance. There is no
reason why we cannot calculate the bitmap in advance too so that
we don't have to play pointer games.
Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mattst88/alpha
Pull alpha architecture fixes from Matt Turner:
"This contains mostly clean ups and fixes but also an implementation of
atomic64_dec_if_positive() and a pair of new syscalls"
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mattst88/alpha:
alpha: Use handle_percpu_irq for the timer interrupt
alpha: Force the user-visible HZ to a constant 1024.
alpha: Don't if-out dp264_device_interrupt.
alpha: Use __builtin_alpha_rpcc
alpha: Fix type compatibility warning for marvel_map_irq
alpha: Generate dwarf2 unwind info for various kernel entry points.
alpha: Implement atomic64_dec_if_positive
alpha: Improve atomic_add_unless
alpha: Modernize lib/mpi/longlong.h
alpha: Add kcmp and finit_module syscalls
alpha: locks: remove unused arch_*_relax operations
alpha: kernel: typo issue, using '1' instead of '11'
alpha: kernel: using memcpy() instead of strcpy()
alpha: Convert print_symbol to %pSR
Merge tag 'trace-3.11-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace
Pull tracing fixes and cleanups from Steven Rostedt:
"This contains fixes, optimizations and some clean ups
Some of the fixes need to go back to 3.10. They are minor, and deal
mostly with incorrect ref counting in accessing event files.
There was a couple of optimizations that should have perf perform a
bit better when accessing trace events.
And some various clean ups. Some of the clean ups are necessary to
help in a fix to a theoretical race between opening a event file and
deleting that event"
* tag 'trace-3.11-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
tracing: Kill the unbalanced tr->ref++ in tracing_buffers_open()
tracing: Kill trace_array->waiter
tracing: Do not (ab)use trace_seq in event_id_read()
tracing: Simplify the iteration logic in f_start/f_next
tracing: Add ref_data to function and fgraph tracer structs
tracing: Miscellaneous fixes for trace_array ref counting
tracing: Fix error handling to ensure instances can always be removed
tracing/kprobe: Wait for disabling all running kprobe handlers
tracing/perf: Move the PERF_MAX_TRACE_SIZE check into perf_trace_buf_prepare()
tracing/syscall: Avoid perf_trace_buf_*() if sys_data->perf_events is empty
tracing/function: Avoid perf_trace_buf_*() if event_function.perf_events is empty
tracing: Typo fix on ring buffer comments
tracing: Use trace_seq_puts()/trace_seq_putc() where possible
tracing: Use correct config guard CONFIG_STACK_TRACER
Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/rzhang/linux
Pull thermal management fixes from Zhang Rui:
"These are fixes collected over the last week, they fixes several
problems caused by the x86_pkg_temp_thermal introduced in 3.11-rc1.
Specifics:
- the x86_pkg_temp_thermal driver causes crash on systems with no
package MSR support as there is a bug in the logic to check
presence of DTHERM and PTS feature together. Added a change so
that when there is no PTS support, module doesn't get loaded.
- fix krealloc() misuse in pkg_temp_thermal_device_add().
If krealloc() returns NULL, it doesn't free the original. Thus if
we want to exit because of the krealloc() failure, we must make
sure the original one is freed.
- The error code path of the x86 package temperature thermal driver's
initialization routine makes an unbalanced call to
get_online_cpus(), which causes subsequent CPU offline operations,
and consequently system suspend, to permanently block in
cpu_hotplug_begin() on systems where get_core_online() returns an
error code.
Remove the extra get_online_cpus() to fix the problem"
* 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/rzhang/linux:
Thermal: Fix lockup of cpu_down()
Thermal: x86_pkg_temp: Limit number of pkg temp zones
Thermal: x86_pkg_temp: fix krealloc() misuse in in pkg_temp_thermal_device_add()
Thermal: x86 package temp thermal crash
Merge tag 'gpio-for-v3.11-2' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-gpio
Pull gpio fixes from Linus Walleij:
"A first round of GPIO fixes for the v3.11 series:
- OMAP device tree boot fix
- Handle an error condition in the MSM driver
The OMAP patches have been around since around the merge window, but
since they first caused more breakage I let them boil in -next for a
while. These should be fine now"
* tag 'gpio-for-v3.11-2' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-gpio:
drivers: gpio: msm: Fix the error condition for reading ngpio
gpio/omap: fix build error when OF_GPIO is not defined.
gpio/omap: auto request GPIO as input if used as IRQ via DT
gpio/omap: don't create an IRQ mapping for every GPIO on DT
Merge branch 'for-3.11/drivers' of git://git.kernel.dk/linux-block
Pull block IO driver bits from Jens Axboe:
"As I mentioned in the core block pull request, due to real life
circumstances the driver pull request would be late. Now it looks
like -rc2 late... On the plus side, apart form the rsxx update, these
are all things that I could argue could go in later in the cycle as
they are fixes and not features. So even though things are late, it's
not ALL bad.
The pull request contains:
- Updates to bcache, all bug fixes, from Kent.
- A pile of drbd bug fixes (no big features this time!).
- xen blk front/back fixes.
- rsxx driver updates, some of them deferred form 3.10. So should be
well cooked by now"
* 'for-3.11/drivers' of git://git.kernel.dk/linux-block: (63 commits)
bcache: Allocation kthread fixes
bcache: Fix GC_SECTORS_USED() calculation
bcache: Journal replay fix
bcache: Shutdown fix
bcache: Fix a sysfs splat on shutdown
bcache: Advertise that flushes are supported
bcache: check for allocation failures
bcache: Fix a dumb race
bcache: Use standard utility code
bcache: Update email address
bcache: Delete fuzz tester
bcache: Document shrinker reserve better
bcache: FUA fixes
drbd: Allow online change of al-stripes and al-stripe-size
drbd: Constants should be UPPERCASE
drbd: Ignore the exit code of a fence-peer handler if it returns too late
drbd: Fix rcu_read_lock balance on error path
drbd: fix error return code in drbd_init()
drbd: Do not sleep inside rcu
bcache: Refresh usage docs
...
Steven Rostedt [Tue, 16 Jul 2013 18:02:28 +0000 (14:02 -0400)]
Thermal: Fix lockup of cpu_down()
Commit f1a18a105 "Thermal: CPU Package temperature thermal" had code
that did a get_online_cpus(), run a loop and then do a
put_online_cpus(). The problem is that the loop had an error exit that
would skip the put_online_cpus() part.
In the error exit part of the function, it also did a get_online_cpus(),
run a loop and then put_online_cpus(). The only way to get to the error
exit part is with get_online_cpus() already performed. If this error
condition is hit, the system will be prevented from taking CPUs offline.
The process taking the CPU offline will lock up hard.
Removing the get_online_cpus() removes the lockup as the hotplug CPU
refcount is back to zero.
This was bisected with ktest.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Zhang Rui <rui.zhang@intel.com>
Merge tag 'acpi-video-3.11' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm
Pull ACPI video support fixes from Rafael Wysocki:
"I'm sending a separate pull request for this as it may be somewhat
controversial. The breakage addressed here is not really new and the
fixes may not satisfy all users of the affected systems, but we've had
so much back and forth dance in this area over the last several weeks
that I think it's time to actually make some progress.
The source of the problem is that about a year ago we started to tell
BIOSes that we're compatible with Windows 8, which we really need to
do, because some systems shipping with Windows 8 are tested with it
and nothing else, so if we tell their BIOSes that we aren't compatible
with Windows 8, we expose our users to untested BIOS/AML code paths.
However, as it turns out, some Windows 8-specific AML code paths are
not tested either, because Windows 8 actually doesn't use the ACPI
methods containing them, so if we declare Windows 8 compatibility and
attempt to use those ACPI methods, things break. That occurs mostly
in the backlight support area where in particular the _BCM and _BQC
methods are plain unusable on some systems if the OS declares Windows
8 compatibility.
[ The additional twist is that they actually become usable if the OS
says it is not compatible with Windows 8, but that may cause
problems to show up elsewhere ]
Investigation carried out by Matthew Garrett indicates that what
Windows 8 does about backlight is to leave backlight control up to
individual graphics drivers. At least there's evidence that it does
that if the Intel graphics driver is used, so we've decided to follow
Windows 8 in that respect and allow i915 to control backlight (Daniel
likes that part).
The first commit from Aaron Lu makes ACPICA export the variable from
which we can infer whether or not the BIOS believes that we are
compatible with Windows 8.
The second commit from Matthew Garrett prepares the ACPI video driver
by making it initialize the ACPI backlight even if it is not going to
be used afterward (that is needed for backlight control to work on
Thinkpads).
The third commit implements the actual workaround making i915 take
over backlight control if the firmware thinks it's dealing with
Windows 8 and is based on the work of multiple developers, including
Matthew Garrett, Chun-Yi Lee, Seth Forshee, and Aaron Lu.
The final commit from Aaron Lu makes us follow Windows 8 by informing
the firmware through the _DOS method that it should not carry out
automatic brightness changes, so that brightness can be controlled by
GUI.
Hopefully, this approach will allow us to avoid using blacklists of
systems that should not declare Windows 8 compatibility just to avoid
backlight control problems in the future.
- Change from Aaron Lu makes ACPICA export a variable which can be
used by driver code to determine whether or not the BIOS believes
that we are compatible with Windows 8.
- Change from Matthew Garrett makes the ACPI video driver initialize
the ACPI backlight even if it is not going to be used afterward
(that is needed for backlight control to work on Thinkpads).
- Fix from Rafael J Wysocki implements Windows 8 backlight support
workaround making i915 take over bakclight control if the firmware
thinks it's dealing with Windows 8. Based on the work of multiple
developers including Matthew Garrett, Chun-Yi Lee, Seth Forshee,
and Aaron Lu.
- Fix from Aaron Lu makes the kernel follow Windows 8 by informing
the firmware through the _DOS method that it should not carry out
automatic brightness changes, so that brightness can be controlled
by GUI"
* tag 'acpi-video-3.11' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
ACPI / video: no automatic brightness changes by win8-compatible firmware
ACPI / video / i915: No ACPI backlight if firmware expects Windows 8
ACPI / video: Always call acpi_video_init_brightness() on init
ACPICA: expose OSI version
projects / linux-beck.git / log