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Currently the rcu_torture_fakewriter() function invokes cur_ops->sync()
and cur_ops->exp_sync() without first checking to see if they are in
fact non-NULL. This results in kernel NULL pointer dereferences when
testing RCU implementations that choose not to provide the full set of
primitives. Given that it is perfectly reasonable to have specialized
RCU implementations that provide only a subset of the RCU API, this is
a bug in rcutorture.
This commit therefore makes rcu_torture_fakewriter() check function
pointers before invoking them, thus allowing it to test subsetted
RCU implementations.
Reported-by: Lihao Liang <lianglihao@huawei.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
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This commit moves to __func__ for function names and for KBUILD_MODNAME
for module names, all in the name of better resilience to change.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
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This commit replaces array-allocation calls to kzalloc() with
equivalent calls to kcalloc().
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
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The code in srcu_gp_end() inserts a delay every 0x3ff grace periods in
order to prevent SRCU grace-period work from consuming an entire CPU
when there is a long sequence of expedited SRCU grace-period requests.
However, all of SRCU's grace-period work is carried out in workqueues,
which are in turn within kthreads, which are automatically throttled as
needed by the scheduler. In particular, if there is plenty of idle time,
there is no point in throttling.
This commit therefore removes the expedited SRCU grace-period throttling.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
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Of course, compilers will optimize out a dead code. Anyway, remove
any dead code for better readibility.
Signed-off-by: Byungchul Park <byungchul.park@lge.com>
Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
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Currently, given a multi-level srcu_node tree, SRCU can scan the full
set of srcu_data structures at each level when cleaning up after a grace
period. This, though harmless otherwise, represents pointless overhead.
This commit therefore eliminates this overhead by scanning the srcu_data
structures only when traversing the leaf srcu_node structures.
Signed-off-by: Ildar Ismagilov <devix84@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
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SRCU checks each srcu_data structure's grace-period number for counter
wrap four times per cycle by default. This frequency guarantees that
normal comparisons will detect potential wrap. However, the expedited
grace-period number is not checked. The consquences are not too horrible
(a failure to expedite a grace period when requested), but it would be
good to avoid such things. This commit therefore adds this check to
the expedited grace-period number.
Signed-off-by: Ildar Ismagilov <devix84@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
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This commit moves to __func__ for function names in the name of better
resilience to change.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
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This commit reworks the first loop in sync_rcu_exp_select_cpus()
to avoid doing unnecssary stores to other CPUs' rcu_data
structures. This speeds up that first loop by roughly a factor of
two on an old x86 system. In the case where the system is mostly
idle, this loop incurs a large fraction of the overhead of the
synchronize_rcu_expedited(). There is less benefit on busy systems
because the overhead of the smp_call_function_single() in the second
loop dominates in that case.
However, it is not unusual to do configuration chances involving
RCU grace periods (both expedited and normal) while the system is
mostly idle, so this optimization is worth doing.
While we are in the area, this commit also adds parentheses to arguments
used by the for_each_leaf_node_possible_cpu() macro.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
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If a CPU is transitioning to or from offline state, an expedited
grace period may undergo a timed wait. This timed wait can unduly
delay grace periods, so this commit adds a trace statement to make
it visible.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
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This commit adds more tracing of expedited grace periods to enable
improved debugging of slowdowns.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
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The srcu_funnel_exp_start() function checks to see if the srcu_struct
structure's expedited grace period counter needs updating to reflect a
newly arrived request for an expedited SRCU grace period. Unfortunately,
the check is backwards, so this commit reverses the sense of the test.
Signed-off-by: Ildar Ismagilov <devix84@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
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Commits c0b334c5bfa9 and ea9b0c8a26a2 introduced new sparse warnings
by accessing rcu_node->lock directly and ignoring the __private
marker. Introduce a new wrapper and use it. Also fix a similar problem
in srcutree.c introduced by a3883df3935e.
Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
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RCU's nxttail has been optimized to be a rcu_segcblist, which is
a multi-tailed linked list with macros defined for the indexes for
each tail. The indexes have been defined in linux/rcu_segcblist.h,
so this commit removes the redundant definitions in kernel/rcu/tree.h.
Signed-off-by: Liu Changcheng <changcheng.liu@intel.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
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The kernel/rcu/rcu.h file has a pair of consecutive #ifdefs on
CONFIG_TINY_RCU, so this commit consolidates them, thus saving a few
lines of code.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
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It is not always obvious that the stack dump from a starved grace-period
kthread isn't instead that of a CPU stalling the current grace period.
This commit therefore adds a pr_err() flagging these dumps.
Reported-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
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The debugfs interface displayed statistics on RCU-pending checks but
this interface has since been removed. This commit therefore removes the
no-longer-used rcu_state structure's ->n_force_qs_lh and ->n_force_qs_ngp
fields along with their updates. (Though the ->n_force_qs_ngp field
was actually not used at all, embarrassingly enough.)
If this information proves necessary in the future, the corresponding
event traces will be added.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
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The debugfs interface displayed statistics on RCU-pending checks
but this interface has since been removed. This commit therefore
removes the no-longer-used rcu_data structure's ->n_rcu_pending,
->n_rp_core_needs_qs, ->n_rp_report_qs, ->n_rp_cb_ready,
->n_rp_cpu_needs_gp, ->n_rp_gp_completed, ->n_rp_gp_started,
->n_rp_nocb_defer_wakeup, and ->n_rp_need_nothing fields along with
their updates.
If this information proves necessary in the future, the corresponding
event traces will be added.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
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The debugfs interface displayed statistics on RCU callback invocation but
this interface has since been removed. This commit therefore removes the
no-longer-used rcu_data structure's ->n_cbs_invoked and ->n_nocbs_invoked
fields along with their updates.
If this information proves necessary in the future, the corresponding
event traces will be added.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
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The debugfs interface displayed statistics on RCU priority boosting,
but this interface has since been removed. This commit therefore
removes the no-longer-used rcu_data structure's ->n_tasks_boosted,
->n_exp_boosts, and ->n_exp_boosts and their updates.
If this information proves necessary in the future, the corresponding
event traces will be added.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
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When RCU stall warning triggers, it can print out a lot of messages
while holding spinlocks. If the console device is slow (e.g. an
actual or IPMI serial console), it may end up triggering NMI hard
lockup watchdog like the following.
*** CPU printking while holding RCU spinlock
PID: 4149739 TASK: ffff881a46baa880 CPU: 13 COMMAND: "CPUThreadPool8"
#0 [ffff881fff945e48] crash_nmi_callback at ffffffff8103f7d0
#1 [ffff881fff945e58] nmi_handle at ffffffff81020653
#2 [ffff881fff945eb0] default_do_nmi at ffffffff81020c36
#3 [ffff881fff945ed0] do_nmi at ffffffff81020d32
#4 [ffff881fff945ef0] end_repeat_nmi at ffffffff81956a7e
[exception RIP: io_serial_in+21]
RIP: ffffffff81630e55 RSP: ffff881fff943b88 RFLAGS: 00000002
RAX: 000000000000ca00 RBX: ffffffff8230e188 RCX: 0000000000000000
RDX: 00000000000002fd RSI: 0000000000000005 RDI: ffffffff8230e188
RBP: ffff881fff943bb0 R8: 0000000000000000 R9: ffffffff820cb3c4
R10: 0000000000000019 R11: 0000000000002000 R12: 00000000000026e1
R13: 0000000000000020 R14: ffffffff820cd398 R15: 0000000000000035
ORIG_RAX: ffffffffffffffff CS: 0010 SS: 0000
--- <NMI exception stack> ---
#5 [ffff881fff943b88] io_serial_in at ffffffff81630e55
#6 [ffff881fff943b90] wait_for_xmitr at ffffffff8163175c
#7 [ffff881fff943bb8] serial8250_console_putchar at ffffffff816317dc
#8 [ffff881fff943bd8] uart_console_write at ffffffff8162ac00
#9 [ffff881fff943c08] serial8250_console_write at ffffffff81634691
#10 [ffff881fff943c80] univ8250_console_write at ffffffff8162f7c2
#11 [ffff881fff943c90] console_unlock at ffffffff810dfc55
#12 [ffff881fff943cf0] vprintk_emit at ffffffff810dffb5
#13 [ffff881fff943d50] vprintk_default at ffffffff810e01bf
#14 [ffff881fff943d60] vprintk_func at ffffffff810e1127
#15 [ffff881fff943d70] printk at ffffffff8119a8a4
#16 [ffff881fff943dd0] print_cpu_stall_info at ffffffff810eb78c
#17 [ffff881fff943e88] rcu_check_callbacks at ffffffff810ef133
#18 [ffff881fff943ee8] update_process_times at ffffffff810f3497
#19 [ffff881fff943f10] tick_sched_timer at ffffffff81103037
#20 [ffff881fff943f38] __hrtimer_run_queues at ffffffff810f3f38
#21 [ffff881fff943f88] hrtimer_interrupt at ffffffff810f442b
*** CPU triggering the hardlockup watchdog
PID: 4149709 TASK: ffff88010f88c380 CPU: 26 COMMAND: "CPUThreadPool35"
#0 [ffff883fff1059d0] machine_kexec at ffffffff8104a874
#1 [ffff883fff105a30] __crash_kexec at ffffffff811116cc
#2 [ffff883fff105af0] __crash_kexec at ffffffff81111795
#3 [ffff883fff105b08] panic at ffffffff8119a6ae
#4 [ffff883fff105b98] watchdog_overflow_callback at ffffffff81135dbd
#5 [ffff883fff105bb0] __perf_event_overflow at ffffffff81186866
#6 [ffff883fff105be8] perf_event_overflow at ffffffff81192bc4
#7 [ffff883fff105bf8] intel_pmu_handle_irq at ffffffff8100b265
#8 [ffff883fff105df8] perf_event_nmi_handler at ffffffff8100489f
#9 [ffff883fff105e58] nmi_handle at ffffffff81020653
#10 [ffff883fff105eb0] default_do_nmi at ffffffff81020b94
#11 [ffff883fff105ed0] do_nmi at ffffffff81020d32
#12 [ffff883fff105ef0] end_repeat_nmi at ffffffff81956a7e
[exception RIP: queued_spin_lock_slowpath+248]
RIP: ffffffff810da958 RSP: ffff883fff103e68 RFLAGS: 00000046
RAX: 0000000000000000 RBX: 0000000000000046 RCX: 00000000006d0000
RDX: ffff883fff49a950 RSI: 0000000000d10101 RDI: ffffffff81e54300
RBP: ffff883fff103e80 R8: ffff883fff11a950 R9: 0000000000000000
R10: 000000000e5873ba R11: 000000000000010f R12: ffffffff81e54300
R13: 0000000000000000 R14: ffff88010f88c380 R15: ffffffff81e54300
ORIG_RAX: ffffffffffffffff CS: 0010 SS: 0018
--- <NMI exception stack> ---
#13 [ffff883fff103e68] queued_spin_lock_slowpath at ffffffff810da958
#14 [ffff883fff103e70] _raw_spin_lock_irqsave at ffffffff8195550b
#15 [ffff883fff103e88] rcu_check_callbacks at ffffffff810eed18
#16 [ffff883fff103ee8] update_process_times at ffffffff810f3497
#17 [ffff883fff103f10] tick_sched_timer at ffffffff81103037
#18 [ffff883fff103f38] __hrtimer_run_queues at ffffffff810f3f38
#19 [ffff883fff103f88] hrtimer_interrupt at ffffffff810f442b
--- <IRQ stack> ---
Avoid spuriously triggering NMI hardlockup watchdog by touching it
from the print functions. show_state_filter() shares the same problem
and solution.
v2: Relocate the comment to where it belongs.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
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In CONFIG_RCU_NOCB_CPU=y kernels, if the boot parameters indicate that
none of the CPUs should in fact be offloaded, the following somewhat
obtuse message appears:
Offload RCU callbacks from CPUs: .
This commit therefore makes the message at least grammatically correct
in this case:
Offload RCU callbacks from CPUs: (none)
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
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Since rcu_boot_init_percpu_data() is only called at boot time,
there is no data race and spinlock is not needed.
Signed-off-by: Lihao Liang <lianglihao@huawei.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
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Pull SCSI updates from James Bottomley:
"This is mostly updates of the usual driver suspects: arcmsr,
scsi_debug, mpt3sas, lpfc, cxlflash, qla2xxx, aacraid, megaraid_sas,
hisi_sas.
We also have a rework of the libsas hotplug handling to make it more
robust, a slew of 32 bit time conversions and fixes, and a host of the
usual minor updates and style changes. The biggest potential for
regressions is the libsas hotplug changes, but so far they seem stable
under testing"
* tag 'scsi-misc' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi: (313 commits)
scsi: qla2xxx: Fix logo flag for qlt_free_session_done()
scsi: arcmsr: avoid do_gettimeofday
scsi: core: Add VENDOR_SPECIFIC sense code definitions
scsi: qedi: Drop cqe response during connection recovery
scsi: fas216: fix sense buffer initialization
scsi: ibmvfc: Remove unneeded semicolons
scsi: hisi_sas: fix a bug in hisi_sas_dev_gone()
scsi: hisi_sas: directly attached disk LED feature for v2 hw
scsi: hisi_sas: devicetree: bindings: add LED feature for v2 hw
scsi: megaraid_sas: NVMe passthrough command support
scsi: megaraid: use ktime_get_real for firmware time
scsi: fnic: use 64-bit timestamps
scsi: qedf: Fix error return code in __qedf_probe()
scsi: devinfo: fix format of the device list
scsi: qla2xxx: Update driver version to 10.00.00.05-k
scsi: qla2xxx: Add XCB counters to debugfs
scsi: qla2xxx: Fix queue ID for async abort with Multiqueue
scsi: qla2xxx: Fix warning for code intentation in __qla24xx_handle_gpdb_event()
scsi: qla2xxx: Fix warning during port_name debug print
scsi: qla2xxx: Fix warning in qla2x00_async_iocb_timeout()
...
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'fixes.2017.12.11a', 'srbd.2017.12.05a' and 'torture.2017.12.11a' into HEAD
cond_resched.2017.12.04a: Convert cond_resched_rcu_qs() to cond_resched()
dyntick.2017.11.28a: Make RCU dynticks handle interrupts from NMI
fixes.2017.12.11a: Miscellaneous fixes
srbd.2017.12.05a: Remove now-redundant smp_read_barrier_depends()
torture.2017.12.11a: Torture-testing update
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The purpose of torture_runnable is to allow rcutorture and locktorture
to be started and stopped via sysfs when they are built into the kernel
(as in not compiled as loadable modules). However, the 0444 permissions
for both instances of torture_runnable prevent this use case from ever
being put into practice. Given that there have been no complaints
about this deficiency, it is reasonable to conclude that no one actually
makes use of this sysfs capability. The perf_runnable module parameter
for rcuperf is in the same situation.
This commit therefore removes both torture_runnable instances as well
as perf_runnable.
Reported-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
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This commit attempts to make a very rare rcutorture failure happen
more often by increasing the fraction of RCU-preempt read-side critical
sections that are preempted.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
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This commit adds a torture_preempt_schedule() that is nothingness
in !PREEMPT builds and is preempt_schedule() otherwise. Then
torture_preempt_schedule() is used to eliminate several ugly #ifdefs,
both in rcutorture and in locktorture.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
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Currently have_rcu_nocb_mask is used to avoid double allocation of
rcu_nocb_mask during boot up. Due to different representation of
cpumask_var_t on different kernel config CPUMASK=y(or n) it was okay.
But now we have a helper cpumask_available(), which can be utilized
to check whether rcu_nocb_mask has been allocated or not without using
a variable.
Removing the variable also reduces vmlinux size.
Unpatched version:
text data bss dec hex filename
13050393 7852470 14543408 35446271 21cddff vmlinux
Patched version:
text data bss dec hex filename
13050390 7852438 14543408 35446236 21cdddc vmlinux
Signed-off-by: Rakib Mullick <rakib.mullick@gmail.com>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
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The following statement has for some reason proven non-intuitive:
WARN_ON_ONCE(rcu_segcblist_empty(&rdp->cblist) != (count == 0));
This commit therefore adds a comment that states that this warning
usually triggers in response to a double call_rcu(), which is sort
of like a double free. The comment also suggests building with
CONFIG_DEBUG_OBJECTS_RCU_HEAD=y to track down the double call_rcu().
Reported-by: David Howells <dhowells@redhat.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
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Use of init_rcu_head() and destroy_rcu_head() from modules results in
the following build-time error with CONFIG_DEBUG_OBJECTS_RCU_HEAD=y:
ERROR: "init_rcu_head" [drivers/scsi/scsi_mod.ko] undefined!
ERROR: "destroy_rcu_head" [drivers/scsi/scsi_mod.ko] undefined!
This commit therefore adds EXPORT_SYMBOL_GPL() for each to allow them to
be used by GPL-licensed kernel modules.
Reported-by: Bart Van Assche <Bart.VanAssche@wdc.com>
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
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Invoking queue_delayed_work() while holding a raw spinlock is forbidden
in -rt kernels, which is exactly what __call_srcu() does, indirectly via
srcu_funnel_gp_start(). This commit therefore downgrades Tree SRCU's
locking from raw to non-raw spinlocks, which works because call_srcu()
is not ever called while holding a raw spinlock.
Reported-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
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The code that checks for non-idle non-nohz_idle-usermode tasks invoking
rcu_eqs_enter() and rcu_eqs_exit() prints a considerable quantity of
helpful information. However, these checks fire rarely, so the extra
complexity is no longer worth it. This commit therefore replaces this
debug code with simple WARN_ON_ONCE() statements.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
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There is now only one call to rcu_eqs_exit_common() and there is no other
reason to keep it separate. This commit therefore inlines it into its
sole call site, saving a few lines of code in the process.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
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There is now only one call to rcu_eqs_enter_common() and there is no other
reason to keep it separate. This commit therefore inlines it into its
sole call site, saving a few lines of code in the process.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
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Although ->dynticks_nesting is updated only by process level, it is
accessed from hardirq to check for interrupt-from-idle quiescent states.
Store tearing is thus possible, so this commit applies WRITE_ONCE()
to ->dynticks_nesting stores.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
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The three RCU_LOCKDEP_WARN() calls in rcu_eqs_enter_common() are
redundant with other lockdep checks, so this commit removes them.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
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Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
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Because the ->dynticks_nesting field now only contains the process-based
nesting level instead of a value encoding both the process nesting level
and the irq "nesting" level, we no longer need a long long, even on
32-bit systems. This commit therefore changes both the ->dynticks_nesting
and ->dynticks_nmi_nesting fields to long.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
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Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
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Now that the irq path uses the rcu_nmi_{enter,exit}() algorithm,
rcu_irq_enter() and rcu_irq_exit() may be used from any context. There is
thus no need for rcu_irq_enter_disabled() and for the checks using it.
This commit therefore eliminates rcu_irq_enter_disabled().
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
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Now that ->dynticks_nesting counts only process-level dyntick-idle
entry and exit, there is no need for the elaborate segmented counter
with its guard fields and overflow checking. This commit therefore
makes ->dynticks_nesting be a simple counter.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
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RCU currently uses two different mechanisms for tracking irqs and NMIs.
This is unnecessary complexity: Given that NMIs can nest and given that
RCU's tracking handles such nesting, the NMI tracking mechanism can also
be used to track irqs. This commit therefore defines rcu_irq_enter()
in terms of rcu_nmi_enter() and rcu_irq_exit() in terms of rcu_nmi_exit().
Unfortunately, callers must still distinguish between the irq and NMI
functions because additional actions are taken when an irq interrupts
idle or nohz_full usermode execution, and these actions cannot always
be taken from NMI handlers.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
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In preparation for merging dyntick-idle irq handling into the NMI
algorithm, clamp ->dynticks_nmi_nesting value to allow for interrupts
that enter but never leave and vice versa.
It is important that the clamping happen outside of the extended quiescent
state. Otherwise, there will be short windows where irqs and NMIs fail
to convince RCU to start watching.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
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This is a code-motion-only commit that prepares to define rcu_irq_enter()
in terms of rcu_nmi_enter() and rcu_irq_exit() in terms of rcu_irq_exit().
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
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Both extended-quiescent-state entry and exit first update the nesting
counter and then adjust the dyntick-idle state. This means that there
are four states: (1) Both nesting and dyntick idle indicate idle,
(2) Nesting indicates idle but dyntick idle does not, (3) Nesting indicates
non-idle and dyntick idle does not, and (4) Both nesting and dyntick
idle indicate non-idle. This commit simplifies the state space by
eliminating #3, reversing the order of updates on exit from extended
quiescent state.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
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NMIs can nest, and store tearing could in theory happen on carries
from one byte to the next. This commit therefore adds the WRITE_ONCE()
macros preventing this.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull timer updates from Thomas Gleixner:
"Yet another big pile of changes:
- More year 2038 work from Arnd slowly reaching the point where we
need to think about the syscalls themself.
- A new timer function which allows to conditionally (re)arm a timer
only when it's either not running or the new expiry time is sooner
than the armed expiry time. This allows to use a single timer for
multiple timeout requirements w/o caring about the first expiry
time at the call site.
- A new NMI safe accessor to clock real time for the printk timestamp
work. Can be used by tracing, perf as well if required.
- A large number of timer setup conversions from Kees which got
collected here because either maintainers requested so or they
simply got ignored. As Kees pointed out already there are a few
trivial merge conflicts and some redundant commits which was
unavoidable due to the size of this conversion effort.
- Avoid a redundant iteration in the timer wheel softirq processing.
- Provide a mechanism to treat RTC implementations depending on their
hardware properties, i.e. don't inflict the write at the 0.5
seconds boundary which originates from the PC CMOS RTC to all RTCs.
No functional change as drivers need to be updated separately.
- The usual small updates to core code clocksource drivers. Nothing
really exciting"
* 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (111 commits)
timers: Add a function to start/reduce a timer
pstore: Use ktime_get_real_fast_ns() instead of __getnstimeofday()
timer: Prepare to change all DEFINE_TIMER() callbacks
netfilter: ipvs: Convert timers to use timer_setup()
scsi: qla2xxx: Convert timers to use timer_setup()
block/aoe: discover_timer: Convert timers to use timer_setup()
ide: Convert timers to use timer_setup()
drbd: Convert timers to use timer_setup()
mailbox: Convert timers to use timer_setup()
crypto: Convert timers to use timer_setup()
drivers/pcmcia: omap1: Fix error in automated timer conversion
ARM: footbridge: Fix typo in timer conversion
drivers/sgi-xp: Convert timers to use timer_setup()
drivers/pcmcia: Convert timers to use timer_setup()
drivers/memstick: Convert timers to use timer_setup()
drivers/macintosh: Convert timers to use timer_setup()
hwrng/xgene-rng: Convert timers to use timer_setup()
auxdisplay: Convert timers to use timer_setup()
sparc/led: Convert timers to use timer_setup()
mips: ip22/32: Convert timers to use timer_setup()
...
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler updates from Ingo Molnar:
"The main updates in this cycle were:
- Group balancing enhancements and cleanups (Brendan Jackman)
- Move CPU isolation related functionality into its separate
kernel/sched/isolation.c file, with related 'housekeeping_*()'
namespace and nomenclature et al. (Frederic Weisbecker)
- Improve the interactive/cpu-intense fairness calculation (Josef
Bacik)
- Improve the PELT code and related cleanups (Peter Zijlstra)
- Improve the logic of pick_next_task_fair() (Uladzislau Rezki)
- Improve the RT IPI based balancing logic (Steven Rostedt)
- Various micro-optimizations:
- better !CONFIG_SCHED_DEBUG optimizations (Patrick Bellasi)
- better idle loop (Cheng Jian)
- ... plus misc fixes, cleanups and updates"
* 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (54 commits)
sched/core: Optimize sched_feat() for !CONFIG_SCHED_DEBUG builds
sched/sysctl: Fix attributes of some extern declarations
sched/isolation: Document isolcpus= boot parameter flags, mark it deprecated
sched/isolation: Add basic isolcpus flags
sched/isolation: Move isolcpus= handling to the housekeeping code
sched/isolation: Handle the nohz_full= parameter
sched/isolation: Introduce housekeeping flags
sched/isolation: Split out new CONFIG_CPU_ISOLATION=y config from CONFIG_NO_HZ_FULL
sched/isolation: Rename is_housekeeping_cpu() to housekeeping_cpu()
sched/isolation: Use its own static key
sched/isolation: Make the housekeeping cpumask private
sched/isolation: Provide a dynamic off-case to housekeeping_any_cpu()
sched/isolation, watchdog: Use housekeeping_cpumask() instead of ad-hoc version
sched/isolation: Move housekeeping related code to its own file
sched/idle: Micro-optimize the idle loop
sched/isolcpus: Fix "isolcpus=" boot parameter handling when !CONFIG_CPUMASK_OFFSTACK
x86/tsc: Append the 'tsc=' description for the 'tsc=unstable' boot parameter
sched/rt: Simplify the IPI based RT balancing logic
block/ioprio: Use a helper to check for RT prio
sched/rt: Add a helper to test for a RT task
...
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull core locking updates from Ingo Molnar:
"The main changes in this cycle are:
- Another attempt at enabling cross-release lockdep dependency
tracking (automatically part of CONFIG_PROVE_LOCKING=y), this time
with better performance and fewer false positives. (Byungchul Park)
- Introduce lockdep_assert_irqs_enabled()/disabled() and convert
open-coded equivalents to lockdep variants. (Frederic Weisbecker)
- Add down_read_killable() and use it in the VFS's iterate_dir()
method. (Kirill Tkhai)
- Convert remaining uses of ACCESS_ONCE() to
READ_ONCE()/WRITE_ONCE(). Most of the conversion was Coccinelle
driven. (Mark Rutland, Paul E. McKenney)
- Get rid of lockless_dereference(), by strengthening Alpha atomics,
strengthening READ_ONCE() with smp_read_barrier_depends() and thus
being able to convert users of lockless_dereference() to
READ_ONCE(). (Will Deacon)
- Various micro-optimizations:
- better PV qspinlocks (Waiman Long),
- better x86 barriers (Michael S. Tsirkin)
- better x86 refcounts (Kees Cook)
- ... plus other fixes and enhancements. (Borislav Petkov, Juergen
Gross, Miguel Bernal Marin)"
* 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (70 commits)
locking/x86: Use LOCK ADD for smp_mb() instead of MFENCE
rcu: Use lockdep to assert IRQs are disabled/enabled
netpoll: Use lockdep to assert IRQs are disabled/enabled
timers/posix-cpu-timers: Use lockdep to assert IRQs are disabled/enabled
sched/clock, sched/cputime: Use lockdep to assert IRQs are disabled/enabled
irq_work: Use lockdep to assert IRQs are disabled/enabled
irq/timings: Use lockdep to assert IRQs are disabled/enabled
perf/core: Use lockdep to assert IRQs are disabled/enabled
x86: Use lockdep to assert IRQs are disabled/enabled
smp/core: Use lockdep to assert IRQs are disabled/enabled
timers/hrtimer: Use lockdep to assert IRQs are disabled/enabled
timers/nohz: Use lockdep to assert IRQs are disabled/enabled
workqueue: Use lockdep to assert IRQs are disabled/enabled
irq/softirqs: Use lockdep to assert IRQs are disabled/enabled
locking/lockdep: Add IRQs disabled/enabled assertion APIs: lockdep_assert_irqs_enabled()/disabled()
locking/pvqspinlock: Implement hybrid PV queued/unfair locks
locking/rwlocks: Fix comments
x86/paravirt: Set up the virt_spin_lock_key after static keys get initialized
block, locking/lockdep: Assign a lock_class per gendisk used for wait_for_completion()
workqueue: Remove now redundant lock acquisitions wrt. workqueue flushes
...
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Paul E. McKenney
Byungchul Park
Ildar Ismagilov
Matthew Wilcox
Liu, Changcheng
Tejun Heo
Lihao Liang
Linus Torvalds
Rakib Mullick