25 Dec, 2017
1 commit
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commit 3382290ed2d5e275429cef510ab21889d3ccd164 upstream.
[ Note, this is a Git cherry-pick of the following commit:
506458efaf15 ("locking/barriers: Convert users of lockless_dereference() to READ_ONCE()")
... for easier x86 PTI code testing and back-porting. ]
READ_ONCE() now has an implicit smp_read_barrier_depends() call, so it
can be used instead of lockless_dereference() without any change in
semantics.Signed-off-by: Will Deacon
Cc: Linus Torvalds
Cc: Paul E. McKenney
Cc: Peter Zijlstra
Cc: Thomas Gleixner
Link: http://lkml.kernel.org/r/1508840570-22169-4-git-send-email-will.deacon@arm.com
Signed-off-by: Ingo Molnar
Signed-off-by: Greg Kroah-Hartman
20 Oct, 2017
1 commit
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Because many of RCU's files have not been included into docbook, a
number of errors have accumulated. This commit fixes them.Signed-off-by: Paul E. McKenney
Signed-off-by: Linus Torvalds
08 Sep, 2017
1 commit
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Pull SCSI updates from James Bottomley:
"This is mostly updates of the usual suspects: lpfc, qla2xxx, hisi_sas,
megaraid_sas, zfcp and a host of minor updates.The major driver change here is the elimination of the block based
cciss driver in favour of the SCSI based hpsa driver (which now drives
all the legacy cases cciss used to be required for). Plus a reset
handler clean up and the redo of the SAS SMP handler to use bsg lib"* tag 'scsi-misc' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi: (279 commits)
scsi: scsi-mq: Always unprepare before requeuing a request
scsi: Show .retries and .jiffies_at_alloc in debugfs
scsi: Improve requeuing behavior
scsi: Call scsi_initialize_rq() for filesystem requests
scsi: qla2xxx: Reset the logo flag, after target re-login.
scsi: qla2xxx: Fix slow mem alloc behind lock
scsi: qla2xxx: Clear fc4f_nvme flag
scsi: qla2xxx: add missing includes for qla_isr
scsi: qla2xxx: Fix an integer overflow in sysfs code
scsi: aacraid: report -ENOMEM to upper layer from aac_convert_sgraw2()
scsi: aacraid: get rid of one level of indentation
scsi: aacraid: fix indentation errors
scsi: storvsc: fix memory leak on ring buffer busy
scsi: scsi_transport_sas: switch to bsg-lib for SMP passthrough
scsi: smartpqi: remove the smp_handler stub
scsi: hpsa: remove the smp_handler stub
scsi: bsg-lib: pass the release callback through bsg_setup_queue
scsi: Rework handling of scsi_device.vpd_pg8[03]
scsi: Rework the code for caching Vital Product Data (VPD)
scsi: rcu: Introduce rcu_swap_protected()
...
30 Aug, 2017
1 commit
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A common pattern in RCU code is to assign a new value to an RCU pointer
after having read and stored the old value. Introduce a macro for this
pattern.Signed-off-by: Bart Van Assche
Acked-by: Paul E. McKenney
Cc: Christoph Hellwig
Cc: Hannes Reinecke
Cc: Johannes Thumshirn
Cc: Shane M Seymour
Signed-off-by: Martin K. Petersen
17 Aug, 2017
3 commits
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…isc.2017.08.17a', 'spin_unlock_wait_no.2017.08.17a', 'srcu.2017.07.27c' and 'torture.2017.07.24c' into HEAD
doc.2017.08.17a: Documentation updates.
fixes.2017.08.17a: RCU fixes.
hotplug.2017.07.25b: CPU-hotplug updates.
misc.2017.08.17a: Miscellaneous fixes outside of RCU (give or take conflicts).
spin_unlock_wait_no.2017.08.17a: Remove spin_unlock_wait().
srcu.2017.07.27c: SRCU updates.
torture.2017.07.24c: Torture-test updates. -
Currently, the exit-time support for TASKS_RCU is open-coded in do_exit().
This commit creates exit_tasks_rcu_start() and exit_tasks_rcu_finish()
APIs for do_exit() use. This has the benefit of confining the use of the
tasks_rcu_exit_srcu variable to one file, allowing it to become static.Signed-off-by: Paul E. McKenney
-
The actual use of TASKS_RCU is only when PREEMPT, otherwise RCU-sched
is used instead. This commit therefore makes synchronize_rcu_tasks()
and call_rcu_tasks() available always, but mapped to synchronize_sched()
and call_rcu_sched(), respectively, when !PREEMPT. This approach also
allows some #ifdefs to be removed from rcutorture.Reported-by: Ingo Molnar
Signed-off-by: Paul E. McKenney
Reviewed-by: Masami Hiramatsu
Acked-by: Ingo Molnar
26 Jul, 2017
1 commit
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RCU callbacks must be migrated away from an outgoing CPU, and this is
done near the end of the CPU-hotplug operation, after the outgoing CPU is
long gone. Unfortunately, this means that other CPU-hotplug callbacks
can execute while the outgoing CPU's callbacks are still immobilized
on the long-gone CPU's callback lists. If any of these CPU-hotplug
callbacks must wait, either directly or indirectly, for the invocation
of any of the immobilized RCU callbacks, the system will hang.This commit avoids such hangs by migrating the callbacks away from the
outgoing CPU immediately upon its departure, shortly after the return
from __cpu_die() in takedown_cpu(). Thus, RCU is able to advance these
callbacks and invoke them, which allows all the after-the-fact CPU-hotplug
callbacks to wait on these RCU callbacks without risk of a hang.While in the neighborhood, this commit also moves rcu_send_cbs_to_orphanage()
and rcu_adopt_orphan_cbs() under a pre-existing #ifdef to avoid including
dead code on the one hand and to avoid define-without-use warnings on the
other hand.Reported-by: Jeffrey Hugo
Link: http://lkml.kernel.org/r/db9c91f6-1b17-6136-84f0-03c3c2581ab4@codeaurora.org
Signed-off-by: Paul E. McKenney
Cc: Thomas Gleixner
Cc: Sebastian Andrzej Siewior
Cc: Ingo Molnar
Cc: Anna-Maria Gleixner
Cc: Boris Ostrovsky
Cc: Richard Weinberger
25 Jul, 2017
1 commit
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Other than lockdep support, Tiny RCU has no need for the
scheduler status. However, Tiny SRCU will need this to control
boot-time behavior independent of lockdep. Therefore, this commit
moves rcu_scheduler_starting() from kernel/rcu/tiny_plugin.h to
kernel/rcu/srcutiny.c. This in turn allows the complete removal of
kernel/rcu/tiny_plugin.h.Signed-off-by: Paul E. McKenney
09 Jun, 2017
15 commits
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This commit removes a #ifdef and saves a few lines of code by moving
the rcu_end_inkernel_boot() function from include/linux/rcupdate.h to
include/linux/rcutiny.h (for TINY_RCU) and to include/linux/rcutree.h
(for TREE_RCU).Signed-off-by: Paul E. McKenney
-
The NO_HZ_FULL_SYSIDLE full-system-idle capability was added in 2013
by commit 0edd1b1784cb ("nohz_full: Add full-system-idle state machine"),
but has not been used. This commit therefore removes it.If it turns out to be needed later, this commit can always be reverted.
Signed-off-by: Paul E. McKenney
Cc: Frederic Weisbecker
Cc: Rik van Riel
Cc: Ingo Molnar
Acked-by: Linus Torvalds -
The list of #includes from include/linux/rcupdate.h has grown quite
a bit, so it is time to trim it. This commit moves the #include
of include/linux/ktime.h to include/linux/rcutiny.h, along with the
Tiny-RCU-only function that was the only thing needing ktimem.h. It then
reconstructs the files included into include/linux/ktime.h based on what
is actually needed, with significant help from the 0day Test Robot.This single change reduces the .i file footprint from rcupdate.h from
9018 lines to 7101 lines.Reported-by: Ingo Molnar
Signed-off-by: Paul E. McKenney -
This commit saves a few lines in include/linux/rcupdate.h by moving
to single-line definitions for functions that just return either true
or false, instead of the old style where the two curly braces each get
their own line.Signed-off-by: Paul E. McKenney
-
The rcu_ftrace_dump() function is used only internally to RCU. This
commit therefore moves its declaration from include/linux/rcupdate.h
to kernel/rcu/rcu.h.Reported-by: Ingo Molnar
Signed-off-by: Paul E. McKenney -
The rcu_is_nocb_cpu() function is used only internally to RCU. This
commit therefore moves its declaration from include/linux/rcupdate.h
to kernel/rcu/rcu.h.Reported-by: Ingo Molnar
Signed-off-by: Paul E. McKenney -
The include/linux/rcupdate.h file does not actually need anything from
linux/debugobjects.h, so this commit removes the inclusion.Reported-by: Ingo Molnar
Signed-off-by: Paul E. McKenney -
The RCU_SCHEDULER_INACTIVE, RCU_SCHEDULER_INIT, and RCU_SCHEDULER_RUNNING
definitions are used only within RCU, so this commit moves them from
include/linux/rcupdate.h to kernel/rcu/rcu.h.Reported-by: Ingo Molnar
Signed-off-by: Paul E. McKenney -
The __rcu_is_watching() function is currently not used, aside from
to implement the rcu_is_watching() function. This commit therefore
eliminates __rcu_is_watching(), which has the beneficial side-effect
of shrinking include/linux/rcupdate.h a bit.Reported-by: Ingo Molnar
Signed-off-by: Paul E. McKenney -
This commit saves a few lines in include/linux/rcupdate.h by moving
to single-line definitions for empty functions, instead of the old
style where the two curly braces each get their own line.Reported-by: Ingo Molnar
Signed-off-by: Paul E. McKenney -
The UINT_CMP_GE() and UINT_CMP_LT() macros are not used, so this
commit removes them.Reported-by: Ingo Molnar
Signed-off-by: Paul E. McKenney -
The include/linux/rcupdate.h file contains a number of definitions that
are used only to communicate between rcutorture, rcuperf, and the RCU code
itself. There is no point in having these definitions exposed globally
throughout the kernel, so this commit moves them to kernel/rcu/rcu.h.
This change has the added benefit of shrinking rcupdate.h.Reported-by: Ingo Molnar
Signed-off-by: Paul E. McKenney -
The rcu_gp_is_normal(), rcu_gp_is_expedited(), rcu_expedite_gp(), and
rcu_unexpedite_gp() functions are intended only for use within the
RCU implementation itself -- the sysfs access is what should be used
outside of RCU. This commit therefore moves the declarations for
these functions to kernel/rcu/rcu.h, and also includes this file into
kernel/rcu/rcutorture.c and kernel/rcu/rcuperf.c. This also has the
beneficial effect of shrinking rcupdate.c a bit.Reported-by: Ingo Molnar
Signed-off-by: Paul E. McKenney -
The rcu_expedited and rcu_normal variables are used only by sysctl
and kernel/rcu/update.c, so it does not make sense to their extern
declarations in rcupdate.h. This commit therefore moves these
extern declarations to update.c.Reported-by: Ingo Molnar
Signed-off-by: Paul E. McKenney -
The include/linux/rcupdate.h file is included by more than 200
files, so shrinking it should provide some build-time benefits.
This commit therefore moves several docbook comments from rcupdate.h to
kernel/rcu/update.c, kernel/rcu/tree.c, and kernel/rcu/tree_plugin.h, thus
reducing the number of times that the compiler has to scan these comments.
This likely provides only a small benefit, but every little bit helps.This commit also fixes a malformed bulleted list noted by the 0day
Test Robot.Reported-by: Ingo Molnar
Signed-off-by: Paul E. McKenney
08 Jun, 2017
1 commit
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This commit adds a rcupdate_announce_bootup_oddness() function to
print out non-default values of significant kernel boot parameter
settings to aid in debugging.Signed-off-by: Paul E. McKenney
11 May, 2017
1 commit
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Pull RCU updates from Ingo Molnar:
"The main changes are:- Debloat RCU headers
- Parallelize SRCU callback handling (plus overlapping patches)
- Improve the performance of Tree SRCU on a CPU-hotplug stress test
- Documentation updates
- Miscellaneous fixes"
* 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (74 commits)
rcu: Open-code the rcu_cblist_n_lazy_cbs() function
rcu: Open-code the rcu_cblist_n_cbs() function
rcu: Open-code the rcu_cblist_empty() function
rcu: Separately compile large rcu_segcblist functions
srcu: Debloat the header
srcu: Adjust default auto-expediting holdoff
srcu: Specify auto-expedite holdoff time
srcu: Expedite first synchronize_srcu() when idle
srcu: Expedited grace periods with reduced memory contention
srcu: Make rcutorture writer stalls print SRCU GP state
srcu: Exact tracking of srcu_data structures containing callbacks
srcu: Make SRCU be built by default
srcu: Fix Kconfig botch when SRCU not selected
rcu: Make non-preemptive schedule be Tasks RCU quiescent state
srcu: Expedite srcu_schedule_cbs_snp() callback invocation
srcu: Parallelize callback handling
kvm: Move srcu_struct fields to end of struct kvm
rcu: Fix typo in PER_RCU_NODE_PERIOD header comment
rcu: Use true/false in assignment to bool
rcu: Use bool value directly
...
21 Apr, 2017
1 commit
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Currently, a call to schedule() acts as a Tasks RCU quiescent state
only if a context switch actually takes place. However, just the
call to schedule() guarantees that the calling task has moved off of
whatever tracing trampoline that it might have been one previously.
This commit therefore plumbs schedule()'s "preempt" parameter into
rcu_note_context_switch(), which then records the Tasks RCU quiescent
state, but only if this call to schedule() was -not- due to a preemption.To avoid adding overhead to the common-case context-switch path,
this commit hides the rcu_note_context_switch() check under an existing
non-common-case check.Suggested-by: Steven Rostedt
Signed-off-by: Paul E. McKenney
19 Apr, 2017
1 commit
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The definition of smp_mb__after_unlock_lock() is currently smp_mb()
for CONFIG_PPC and a no-op otherwise. It would be better to instead
provide an architecture-selectable Kconfig option, and select the
strength of smp_mb__after_unlock_lock() based on that option. This
commit therefore creates ARCH_WEAK_RELEASE_ACQUIRE, has PPC select it,
and bases the definition of smp_mb__after_unlock_lock() on this new
ARCH_WEAK_RELEASE_ACQUIRE Kconfig option.Reported-by: Ingo Molnar
Signed-off-by: Paul E. McKenney
Cc: Peter Zijlstra
Cc: Will Deacon
Cc: Boqun Feng
Cc: Benjamin Herrenschmidt
Cc: Paul Mackerras
Acked-by: Michael Ellerman
Cc:
Reviewed-by: Josh Triplett
11 Apr, 2017
1 commit
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Tracing uses rcu_irq_enter() as a way to make sure that RCU is watching when
it needs to use rcu_read_lock() and friends. This is because tracing can
happen as RCU is about to enter user space, or about to go idle, and RCU
does not watch for RCU read side critical sections as it makes the
transition.There is a small location within the RCU infrastructure that rcu_irq_enter()
itself will not work. If tracing were to occur in that section it will break
if it tries to use rcu_irq_enter().Originally, this happens with the stack_tracer, because it will call
save_stack_trace when it encounters stack usage that is greater than any
stack usage it had encountered previously. There was a case where that
happened in the RCU section where rcu_irq_enter() did not work, and lockdep
complained loudly about it. To fix it, stack tracing added a call to be
disabled and RCU would disable stack tracing during the critical section
that rcu_irq_enter() was inoperable. This solution worked, but there are
other cases that use rcu_irq_enter() and it would be a good idea to let RCU
give a way to let others know that rcu_irq_enter() will not work. For
example, in trace events.Another helpful aspect of this change is that it also moves the per cpu
variable called in the RCU critical section into a cache locale along with
other RCU per cpu variables used in that same location.I'm keeping the stack_trace_disable() code, as that still could be used in
the future by places that really need to disable it. And since it's only a
static inline, it wont take up any kernel text if it is not used.Link: http://lkml.kernel.org/r/20170405093207.404f8deb@gandalf.local.home
Acked-by: Paul E. McKenney
Signed-off-by: Steven Rostedt (VMware)
02 Mar, 2017
1 commit
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So rcupdate.h is a pretty complex header, in particular it includes
which includes - creating a
dependency that includes in ,
which prevents the isolation of from the derived
header.Solve part of the problem by decoupling rcupdate.h from completions:
this can be done by separating out the rcu_synchronize types and APIs,
and updating their usage sites.Since this is a mostly RCU-internal types this will not just simplify
's dependencies, but will make all the hundreds of
.c files that include rcupdate.h but not completions or wait.h build
faster.( For rcutiny this means that two dependent APIs have to be uninlined,
but that shouldn't be much of a problem as they are rare variants. )Acked-by: Linus Torvalds
Cc: Mike Galbraith
Cc: Paul E. McKenney
Cc: Peter Zijlstra
Cc: Thomas Gleixner
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar
26 Jan, 2017
1 commit
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If a process invokes synchronize_srcu(), is delayed just the right amount
of time, and thus does not sleep when waiting for the grace period to
complete, there is no ordering between the end of the grace period and
the code following the synchronize_srcu(). Similarly, there can be a
lack of ordering between the end of the SRCU grace period and callback
invocation.This commit adds the necessary ordering.
Reported-by: Lance Roy
Signed-off-by: Paul E. McKenney
[ paulmck: Further smp_mb() adjustment per email with Lance Roy. ]
15 Jan, 2017
1 commit
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The current preemptible RCU implementation goes through three phases
during bootup. In the first phase, there is only one CPU that is running
with preemption disabled, so that a no-op is a synchronous grace period.
In the second mid-boot phase, the scheduler is running, but RCU has
not yet gotten its kthreads spawned (and, for expedited grace periods,
workqueues are not yet running. During this time, any attempt to do
a synchronous grace period will hang the system (or complain bitterly,
depending). In the third and final phase, RCU is fully operational and
everything works normally.This has been OK for some time, but there has recently been some
synchronous grace periods showing up during the second mid-boot phase.
This code worked "by accident" for awhile, but started failing as soon
as expedited RCU grace periods switched over to workqueues in commit
8b355e3bc140 ("rcu: Drive expedited grace periods from workqueue").
Note that the code was buggy even before this commit, as it was subject
to failure on real-time systems that forced all expedited grace periods
to run as normal grace periods (for example, using the rcu_normal ksysfs
parameter). The callchain from the failure case is as follows:early_amd_iommu_init()
|-> acpi_put_table(ivrs_base);
|-> acpi_tb_put_table(table_desc);
|-> acpi_tb_invalidate_table(table_desc);
|-> acpi_tb_release_table(...)
|-> acpi_os_unmap_memory
|-> acpi_os_unmap_iomem
|-> acpi_os_map_cleanup
|-> synchronize_rcu_expeditedThe kernel showing this callchain was built with CONFIG_PREEMPT_RCU=y,
which caused the code to try using workqueues before they were
initialized, which did not go well.This commit therefore reworks RCU to permit synchronous grace periods
to proceed during this mid-boot phase. This commit is therefore a
fix to a regression introduced in v4.9, and is therefore being put
forward post-merge-window in v4.10.This commit sets a flag from the existing rcu_scheduler_starting()
function which causes all synchronous grace periods to take the expedited
path. The expedited path now checks this flag, using the requesting task
to drive the expedited grace period forward during the mid-boot phase.
Finally, this flag is updated by a core_initcall() function named
rcu_exp_runtime_mode(), which causes the runtime codepaths to be used.Note that this arrangement assumes that tasks are not sent POSIX signals
(or anything similar) from the time that the first task is spawned
through core_initcall() time.Fixes: 8b355e3bc140 ("rcu: Drive expedited grace periods from workqueue")
Reported-by: "Zheng, Lv"
Reported-by: Borislav Petkov
Signed-off-by: Paul E. McKenney
Tested-by: Stan Kain
Tested-by: Ivan
Tested-by: Emanuel Castelo
Tested-by: Bruno Pesavento
Tested-by: Borislav Petkov
Tested-by: Frederic Bezies
Cc: # 4.9.0-
23 Aug, 2016
1 commit
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Up to now, RCU has assumed that the CPU-online process makes it from
CPU_UP_PREPARE to set_cpu_online() within one jiffy. Given the recent
rise of virtualized environments, this assumption is very clearly
obsolete. Failing to meet this deadline can result in RCU paying
attention to an incoming CPU for one jiffy, then ignoring it until the
grace period following the one in which that CPU sets itself online.
This situation might prove to be fatally disappointing to any RCU
read-side critical sections that had the misfortune to execute during
the time in which RCU was ignoring the slow-to-come-online CPU.This commit therefore updates RCU's internal CPU state-tracking
information at notify_cpu_starting() time, thus providing RCU with
an exact transition of the CPU's state from offline to online.Note that this means that incoming CPUs must not use RCU read-side
critical section (other than those of SRCU) until notify_cpu_starting()
time. Note also that the CPU_STARTING notifiers -are- allowed to use
RCU read-side critical sections. (Of course, CPU-hotplug notifiers are
rapidly becoming obsolete, so you need to act fast!)If a given architecture or CPU family needs to use RCU read-side
critical sections earlier, the call to rcu_cpu_starting() from
notify_cpu_starting() will need to be architecture-specific, with
architectures that need early use being required to hand-place
the call to rcu_cpu_starting() at some point preceding the call to
notify_cpu_starting().Signed-off-by: Paul E. McKenney
28 Jul, 2016
1 commit
-
Pull networking updates from David Miller:
1) Unified UDP encapsulation offload methods for drivers, from
Alexander Duyck.2) Make DSA binding more sane, from Andrew Lunn.
3) Support QCA9888 chips in ath10k, from Anilkumar Kolli.
4) Several workqueue usage cleanups, from Bhaktipriya Shridhar.
5) Add XDP (eXpress Data Path), essentially running BPF programs on RX
packets as soon as the device sees them, with the option to mirror
the packet on TX via the same interface. From Brenden Blanco and
others.6) Allow qdisc/class stats dumps to run lockless, from Eric Dumazet.
7) Add VLAN support to b53 and bcm_sf2, from Florian Fainelli.
8) Simplify netlink conntrack entry layout, from Florian Westphal.
9) Add ipv4 forwarding support to mlxsw spectrum driver, from Ido
Schimmel, Yotam Gigi, and Jiri Pirko.10) Add SKB array infrastructure and convert tun and macvtap over to it.
From Michael S Tsirkin and Jason Wang.11) Support qdisc packet injection in pktgen, from John Fastabend.
12) Add neighbour monitoring framework to TIPC, from Jon Paul Maloy.
13) Add NV congestion control support to TCP, from Lawrence Brakmo.
14) Add GSO support to SCTP, from Marcelo Ricardo Leitner.
15) Allow GRO and RPS to function on macsec devices, from Paolo Abeni.
16) Support MPLS over IPV4, from Simon Horman.
* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next: (1622 commits)
xgene: Fix build warning with ACPI disabled.
be2net: perform temperature query in adapter regardless of its interface state
l2tp: Correctly return -EBADF from pppol2tp_getname.
net/mlx5_core/health: Remove deprecated create_singlethread_workqueue
net: ipmr/ip6mr: update lastuse on entry change
macsec: ensure rx_sa is set when validation is disabled
tipc: dump monitor attributes
tipc: add a function to get the bearer name
tipc: get monitor threshold for the cluster
tipc: make cluster size threshold for monitoring configurable
tipc: introduce constants for tipc address validation
net: neigh: disallow transition to NUD_STALE if lladdr is unchanged in neigh_update()
MAINTAINERS: xgene: Add driver and documentation path
Documentation: dtb: xgene: Add MDIO node
dtb: xgene: Add MDIO node
drivers: net: xgene: ethtool: Use phy_ethtool_gset and sset
drivers: net: xgene: Use exported functions
drivers: net: xgene: Enable MDIO driver
drivers: net: xgene: Add backward compatibility
drivers: net: phy: xgene: Add MDIO driver
...
06 Jul, 2016
1 commit
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Data structures that are used both with and without RCU protection
are difficult to write in a sparse-clean manner. If you mark the
relevant pointers with __rcu, sparse will complain about all non-RCU
uses, but if you don't mark those pointers, sparse will complain about
all RCU uses.This commit therefore suppresses sparse warnings for rcu_dereference_raw(),
allowing mixed-protection data structures to avoid these warnings.Reported-by: David Howells
Signed-off-by: Paul E. McKenney
Signed-off-by: David Howells
16 Jun, 2016
2 commits
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Currently, if the very first call to call_rcu_tasks() has irqs disabled,
it will create the rcu_tasks_kthread with irqs disabled, which will
result in a splat in the memory allocator, which kthread_run() invokes
with the expectation that irqs are enabled.This commit fixes this problem by deferring kthread creation if called
with irqs disabled. The first call to call_rcu_tasks() that has irqs
enabled will create the kthread.This bug was detected by rcutorture changes that were motivated by
Iftekhar Ahmed's mutation-testing efforts.Signed-off-by: Paul E. McKenney
-
This commit does a compile-time check for rcu_assign_pointer() of NULL,
and uses WRITE_ONCE() rather than smp_store_release() in that case.Reported-by: Christoph Hellwig
Signed-off-by: Paul E. McKenney
15 Jun, 2016
1 commit
-
Signed-off-by: Paul E. McKenney
01 Apr, 2016
2 commits
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Currently, we have four versions of rcu_read_lock_sched_held(), depending
on the combined choices on PREEMPT_COUNT and DEBUG_LOCK_ALLOC. However,
there is an existing function preemptible() that already distinguishes
between the PREEMPT_COUNT=y and PREEMPT_COUNT=n cases, and allows these
four implementations to be consolidated down to two.This commit therefore uses preemptible() to achieve this consolidation.
Note that there could be a small performance regression in the case
of CONFIG_DEBUG_LOCK_ALLOC=y && PREEMPT_COUNT=n. However, given the
overhead associated with CONFIG_DEBUG_LOCK_ALLOC=y, this should be
down in the noise.Signed-off-by: Boqun Feng
Signed-off-by: Paul E. McKenney -
This commit consolidates a couple definitions and several calls for
single-shot ftrace-buffer dumping.Signed-off-by: Paul E. McKenney
