rcu: fix header guard for rcu_all_qs()

rcu_all_qs() is defined for !CONFIG_PREEMPT_RCU but the declaration
is conditioned on CONFIG_PREEMPTION.

With CONFIG_PREEMPT_LAZY, CONFIG_PREEMPTION=y does no

rcu: fix header guard for rcu_all_qs()

rcu_all_qs() is defined for !CONFIG_PREEMPT_RCU but the declaration
is conditioned on CONFIG_PREEMPTION.

With CONFIG_PREEMPT_LAZY, CONFIG_PREEMPTION=y does not imply
CONFIG_PREEMPT_RCU=y.

Decouple the two.

Cc: Paul E. McKenney <[email protected]>
Reviewed-by: Frederic Weisbecker <[email protected]>
Reviewed-by: Sebastian Andrzej Siewior <[email protected]>
Signed-off-by: Ankur Arora <[email protected]>
Signed-off-by: Paul E. McKenney <[email protected]>
Signed-off-by: Boqun Feng <[email protected]>

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slab, rcu: move TINY_RCU variant of kvfree_rcu() to SLAB

Following the move of TREE_RCU implementation, let's move also the
TINY_RCU one for consistency and subsequent refactoring.

For simplicity,

slab, rcu: move TINY_RCU variant of kvfree_rcu() to SLAB

Following the move of TREE_RCU implementation, let's move also the
TINY_RCU one for consistency and subsequent refactoring.

For simplicity, remove the separate inline __kvfree_call_rcu() as
TINY_RCU is not meant for high-performance hardware anyway.

Declare kvfree_call_rcu() in rcupdate.h to avoid header dependency
issues.

Also move the kvfree_rcu_barrier() declaration to slab.h

Reviewed-by: Uladzislau Rezki (Sony) <[email protected]>
Reviewed-by: Joel Fernandes (Google) <[email protected]>
Reviewed-by: Hyeonggon Yoo <[email protected]>
Tested-by: Paul E. McKenney <[email protected]>
Signed-off-by: Vlastimil Babka <[email protected]>

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rcu: Delete unused rcu_gp_might_be_stalled() function

The rcu_gp_might_be_stalled() function is no longer used, so this commit
removes it.

Signed-off-by: Paul E. McKenney <[email protected]>
Revie

rcu: Delete unused rcu_gp_might_be_stalled() function

The rcu_gp_might_be_stalled() function is no longer used, so this commit
removes it.

Signed-off-by: Paul E. McKenney <[email protected]>
Reviewed-by: Joel Fernandes (Google) <[email protected]>
Signed-off-by: Frederic Weisbecker <[email protected]>

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rcu/kvfree: Add kvfree_rcu_barrier() API

Add a kvfree_rcu_barrier() function. It waits until all
in-flight pointers are freed over RCU machinery. It does
not wait any GP completion and it is within

rcu/kvfree: Add kvfree_rcu_barrier() API

Add a kvfree_rcu_barrier() function. It waits until all
in-flight pointers are freed over RCU machinery. It does
not wait any GP completion and it is within its right to
return immediately if there are no outstanding pointers.

This function is useful when there is a need to guarantee
that a memory is fully freed before destroying memory caches.
For example, during unloading a kernel module.

Signed-off-by: Uladzislau Rezki (Sony) <[email protected]>
Signed-off-by: Vlastimil Babka <[email protected]>

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rcu: Rename rcu_momentary_dyntick_idle() into rcu_momentary_eqs()

The context_tracking.state RCU_DYNTICKS subvariable has been renamed to
RCU_WATCHING, replace "dyntick_idle" into "eqs" to drop the

rcu: Rename rcu_momentary_dyntick_idle() into rcu_momentary_eqs()

The context_tracking.state RCU_DYNTICKS subvariable has been renamed to
RCU_WATCHING, replace "dyntick_idle" into "eqs" to drop the dyntick
reference.

Signed-off-by: Valentin Schneider <[email protected]>
Reviewed-by: Frederic Weisbecker <[email protected]>
Signed-off-by: Neeraj Upadhyay <[email protected]>

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rcu: Standardize explicit CPU-hotplug calls

rcu_report_dead() and rcutree_migrate_callbacks() have their headers in
rcupdate.h while those are pure rcutree calls, like the other CPU-hotplug
function

rcu: Standardize explicit CPU-hotplug calls

rcu_report_dead() and rcutree_migrate_callbacks() have their headers in
rcupdate.h while those are pure rcutree calls, like the other CPU-hotplug
functions.

Also rcu_cpu_starting() and rcu_report_dead() have different naming
conventions while they mirror each other's effects.

Fix the headers and propose a naming that relates both functions and
aligns with the prefix of other rcutree CPU-hotplug functions.

Reviewed-by: Paul E. McKenney <[email protected]>
Signed-off-by: Frederic Weisbecker <[email protected]>

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rcu: Conditionally build CPU-hotplug teardown callbacks

Among the three CPU-hotplug teardown RCU callbacks, two of them early
exit if CONFIG_HOTPLUG_CPU=n, and one is left unchanged. In any case
all

rcu: Conditionally build CPU-hotplug teardown callbacks

Among the three CPU-hotplug teardown RCU callbacks, two of them early
exit if CONFIG_HOTPLUG_CPU=n, and one is left unchanged. In any case
all of them have an implementation when CONFIG_HOTPLUG_CPU=n.

Align instead with the common way to deal with CPU-hotplug teardown
callbacks and provide a proper stub when they are not supported.

Reviewed-by: Paul E. McKenney <[email protected]>
Signed-off-by: Frederic Weisbecker <[email protected]>

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rcu: Remove unused function declaration rcu_eqs_special_set()

Commit a86baa69c2b7 ("rcu: Remove special bit at the bottom of the ->dynticks counter")
left behind this, remove it.

Signed-off-by: Yue

rcu: Remove unused function declaration rcu_eqs_special_set()

Commit a86baa69c2b7 ("rcu: Remove special bit at the bottom of the ->dynticks counter")
left behind this, remove it.

Signed-off-by: Yue Haibing <[email protected]>
Signed-off-by: Paul E. McKenney <[email protected]>
Signed-off-by: Frederic Weisbecker <[email protected]>

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rcu: Export rcu_request_urgent_qs_task()

If a CPU is executing a long series of non-sleeping system calls,
RCU grace periods can be delayed for on the order of a couple hundred
milliseconds. This i

rcu: Export rcu_request_urgent_qs_task()

If a CPU is executing a long series of non-sleeping system calls,
RCU grace periods can be delayed for on the order of a couple hundred
milliseconds. This is normally not a problem, but if each system call
does a call_rcu(), those callbacks can stack up. RCU will eventually
notice this callback storm, but use of rcu_request_urgent_qs_task()
allows the code invoking call_rcu() to give RCU a heads up.

This function is not for general use, not yet, anyway.

Reported-by: Alexei Starovoitov <[email protected]>
Signed-off-by: Paul E. McKenney <[email protected]>
Signed-off-by: Alexei Starovoitov <[email protected]>
Signed-off-by: Daniel Borkmann <[email protected]>
Link: https://lore.kernel.org/bpf/[email protected]

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rcu: Refactor kvfree_call_rcu() and high-level helpers

Currently a kvfree_call_rcu() takes an offset within a structure as
a second parameter, so a helper such as a kvfree_rcu_arg_2() has to
convert

rcu: Refactor kvfree_call_rcu() and high-level helpers

Currently a kvfree_call_rcu() takes an offset within a structure as
a second parameter, so a helper such as a kvfree_rcu_arg_2() has to
convert rcu_head and a freed ptr to an offset in order to pass it. That
leads to an extra conversion on macro entry.

Instead of converting, refactor the code in way that a pointer that has
to be freed is passed directly to the kvfree_call_rcu().

This patch does not make any functional change and is transparent to
all kvfree_rcu() users.

Signed-off-by: Uladzislau Rezki (Sony) <[email protected]>
Signed-off-by: Paul E. McKenney <[email protected]>

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rcu: Remove rcu_is_idle_cpu()

The commit 3fcd6a230fa7 ("x86/cpu: Avoid cpuinfo-induced IPIing of
idle CPUs") introduced rcu_is_idle_cpu() in order to identify the
current CPU idle state. But commit

rcu: Remove rcu_is_idle_cpu()

The commit 3fcd6a230fa7 ("x86/cpu: Avoid cpuinfo-induced IPIing of
idle CPUs") introduced rcu_is_idle_cpu() in order to identify the
current CPU idle state. But commit f3eca381bd49 ("x86/aperfmperf:
Replace arch_freq_get_on_cpu()") switched to using MAX_SAMPLE_AGE,
so rcu_is_idle_cpu() is no longer used. This commit therefore removes it.

Fixes: f3eca381bd49 ("x86/aperfmperf: Replace arch_freq_get_on_cpu()")
Signed-off-by: Yipeng Zou <[email protected]>
Reviewed-by: Frederic Weisbecker <[email protected]>
Signed-off-by: Paul E. McKenney <[email protected]>

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rcu: Remove unused 'cpu' in rcu_virt_note_context_switch()

This commit removes the unused function argument 'cpu'. This does not
change functionality, but might save a cycle or two.

Signed-off-by:

rcu: Remove unused 'cpu' in rcu_virt_note_context_switch()

This commit removes the unused function argument 'cpu'. This does not
change functionality, but might save a cycle or two.

Signed-off-by: Zeng Heng <[email protected]>
Acked-by: Mukesh Ojha <[email protected]>
Signed-off-by: Paul E. McKenney <[email protected]>

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rcu: Add functions to compare grace-period state values

This commit adds same_state_synchronize_rcu() and
same_state_synchronize_rcu_full() functions to compare grace-period state
values, for exampl

rcu: Add functions to compare grace-period state values

This commit adds same_state_synchronize_rcu() and
same_state_synchronize_rcu_full() functions to compare grace-period state
values, for example, those obtained from get_state_synchronize_rcu()
and get_state_synchronize_rcu_full(). These functions allow small
structures to omit these state values by placing them in list headers for
lists containing structures with the same token value. Presumably the
per-structure list pointers are the same ones used to link the structures
into whatever reader-accessible data structure was used.

This commit also adds both NUM_ACTIVE_RCU_POLL_OLDSTATE and
NUM_ACTIVE_RCU_POLL_FULL_OLDSTATE, which define the maximum number of
distinct unsigned long values and rcu_gp_oldstate values, respectively,
corresponding to not-yet-completed grace periods. These values can be
used to size arrays of the list headers described above.

Signed-off-by: Paul E. McKenney <[email protected]>

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rcu: Remove ->rgos_polled field from rcu_gp_oldstate structure

Because both normal and expedited grace periods increment their respective
counters on their pre-scheduler early boot fastpaths, the rc

rcu: Remove ->rgos_polled field from rcu_gp_oldstate structure

Because both normal and expedited grace periods increment their respective
counters on their pre-scheduler early boot fastpaths, the rcu_gp_oldstate
structure no longer needs its ->rgos_polled field. This commit therefore
removes this field, shrinking this structure so that it is the same size
as an rcu_head structure.

Signed-off-by: Paul E. McKenney <[email protected]>

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rcu: Add full-sized polling for cond_sync_exp_full()

The cond_synchronize_rcu_expedited() API compresses the combined expedited and
normal grace-period states into a single unsigned long, which cons

rcu: Add full-sized polling for cond_sync_exp_full()

The cond_synchronize_rcu_expedited() API compresses the combined expedited and
normal grace-period states into a single unsigned long, which conserves
storage, but can miss grace periods in certain cases involving overlapping
normal and expedited grace periods. Missing the occasional grace period
is usually not a problem, but there are use cases that care about each
and every grace period.

This commit therefore adds yet another member of the full-state RCU
grace-period polling API, which is the cond_synchronize_rcu_exp_full()
function. This uses up to three times the storage (rcu_gp_oldstate
structure instead of unsigned long), but is guaranteed not to miss
grace periods.

Signed-off-by: Paul E. McKenney <[email protected]>

show more ...

rcu: Add full-sized polling for cond_sync_full()

The cond_synchronize_rcu() API compresses the combined expedited and
normal grace-period states into a single unsigned long, which conserves
storage,

rcu: Add full-sized polling for cond_sync_full()

The cond_synchronize_rcu() API compresses the combined expedited and
normal grace-period states into a single unsigned long, which conserves
storage, but can miss grace periods in certain cases involving overlapping
normal and expedited grace periods. Missing the occasional grace period
is usually not a problem, but there are use cases that care about each
and every grace period.

This commit therefore adds yet another member of the full-state RCU
grace-period polling API, which is the cond_synchronize_rcu_full()
function. This uses up to three times the storage (rcu_gp_oldstate
structure instead of unsigned long), but is guaranteed not to miss
grace periods.

[ paulmck: Apply feedback from kernel test robot and Julia Lawall. ]

Signed-off-by: Paul E. McKenney <[email protected]>

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rcu: Add full-sized polling for start_poll_expedited()

The start_poll_synchronize_rcu_expedited() API compresses the combined
expedited and normal grace-period states into a single unsigned long,
wh

rcu: Add full-sized polling for start_poll_expedited()

The start_poll_synchronize_rcu_expedited() API compresses the combined
expedited and normal grace-period states into a single unsigned long,
which conserves storage, but can miss grace periods in certain cases
involving overlapping normal and expedited grace periods. Missing the
occasional grace period is usually not a problem, but there are use
cases that care about each and every grace period.

This commit therefore adds yet another member of the
full-state RCU grace-period polling API, which is the
start_poll_synchronize_rcu_expedited_full() function. This uses up to
three times the storage (rcu_gp_oldstate structure instead of unsigned
long), but is guaranteed not to miss grace periods.

[ paulmck: Apply feedback from kernel test robot and Julia Lawall. ]

Signed-off-by: Paul E. McKenney <[email protected]>

show more ...

rcu: Add full-sized polling for start_poll()

The start_poll_synchronize_rcu() API compresses the combined expedited and
normal grace-period states into a single unsigned long, which conserves
storag

rcu: Add full-sized polling for start_poll()

The start_poll_synchronize_rcu() API compresses the combined expedited and
normal grace-period states into a single unsigned long, which conserves
storage, but can miss grace periods in certain cases involving overlapping
normal and expedited grace periods. Missing the occasional grace period
is usually not a problem, but there are use cases that care about each
and every grace period.

This commit therefore adds the next member of the full-state RCU
grace-period polling API, namely the start_poll_synchronize_rcu_full()
function. This uses up to three times the storage (rcu_gp_oldstate
structure instead of unsigned long), but is guaranteed not to miss
grace periods.

Signed-off-by: Paul E. McKenney <[email protected]>

show more ...

rcu: Add full-sized polling for get_state()

The get_state_synchronize_rcu() API compresses the combined expedited and
normal grace-period states into a single unsigned long, which conserves
storage,

rcu: Add full-sized polling for get_state()

The get_state_synchronize_rcu() API compresses the combined expedited and
normal grace-period states into a single unsigned long, which conserves
storage, but can miss grace periods in certain cases involving overlapping
normal and expedited grace periods. Missing the occasional grace period
is usually not a problem, but there are use cases that care about each
and every grace period.

This commit therefore adds the next member of the full-state RCU
grace-period polling API, namely the get_state_synchronize_rcu_full()
function. This uses up to three times the storage (rcu_gp_oldstate
structure instead of unsigned long), but is guaranteed not to miss
grace periods.

Signed-off-by: Paul E. McKenney <[email protected]>

show more ...

rcu: Add full-sized polling for get_completed*() and poll_state*()

The get_completed_synchronize_rcu() and poll_state_synchronize_rcu()
APIs compress the combined expedited and normal grace-period s

rcu: Add full-sized polling for get_completed*() and poll_state*()

The get_completed_synchronize_rcu() and poll_state_synchronize_rcu()
APIs compress the combined expedited and normal grace-period states into a
single unsigned long, which conserves storage, but can miss grace periods
in certain cases involving overlapping normal and expedited grace periods.
Missing the occasional grace period is usually not a problem, but there
are use cases that care about each and every grace period.

This commit therefore adds the first members of the full-state RCU
grace-period polling API, namely the get_completed_synchronize_rcu_full()
and poll_state_synchronize_rcu_full() functions. These use up to three
times the storage (rcu_gp_oldstate structure instead of unsigned long),
but which are guaranteed not to miss grace periods, at least in situations
where the single-CPU grace-period optimization does not apply.

Signed-off-by: Paul E. McKenney <[email protected]>

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rcu: Add polled expedited grace-period primitives

This commit adds expedited grace-period functionality to RCU's polled
grace-period API, adding start_poll_synchronize_rcu_expedited() and
cond_synch

rcu: Add polled expedited grace-period primitives

This commit adds expedited grace-period functionality to RCU's polled
grace-period API, adding start_poll_synchronize_rcu_expedited() and
cond_synchronize_rcu_expedited(), which are similar to the existing
start_poll_synchronize_rcu() and cond_synchronize_rcu() functions,
respectively.

Note that although start_poll_synchronize_rcu_expedited() can be invoked
very early, the resulting expedited grace periods are not guaranteed
to start until after workqueues are fully initialized. On the other
hand, both synchronize_rcu() and synchronize_rcu_expedited() can also
be invoked very early, and the resulting grace periods will be taken
into account as they occur.

[ paulmck: Apply feedback from Neeraj Upadhyay. ]

Link: https://lore.kernel.org/all/[email protected]/
Link: https://docs.google.com/document/d/1RNKWW9jQyfjxw2E8dsXVTdvZYh0HnYeSHDKog9jhdN8/edit?usp=sharing
Cc: Brian Foster <[email protected]>
Cc: Dave Chinner <[email protected]>
Cc: Al Viro <[email protected]>
Cc: Ian Kent <[email protected]>
Signed-off-by: Paul E. McKenney <[email protected]>

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rcu/context-tracking: Remove unused and/or unecessary middle functions

Some eqs functions are now only used internally by context tracking, so
their public declarations can be removed.

Also middle

rcu/context-tracking: Remove unused and/or unecessary middle functions

Some eqs functions are now only used internally by context tracking, so
their public declarations can be removed.

Also middle functions such as rcu_user_*() and rcu_idle_*()
which now directly call to rcu_eqs_enter() and rcu_eqs_exit() can be
wiped out as well.

Signed-off-by: Frederic Weisbecker <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Neeraj Upadhyay <[email protected]>
Cc: Uladzislau Rezki <[email protected]>
Cc: Joel Fernandes <[email protected]>
Cc: Boqun Feng <[email protected]>
Cc: Nicolas Saenz Julienne <[email protected]>
Cc: Marcelo Tosatti <[email protected]>
Cc: Xiongfeng Wang <[email protected]>
Cc: Yu Liao <[email protected]>
Cc: Phil Auld <[email protected]>
Cc: Paul Gortmaker<[email protected]>
Cc: Alex Belits <[email protected]>
Signed-off-by: Paul E. McKenney <[email protected]>
Reviewed-by: Nicolas Saenz Julienne <[email protected]>
Tested-by: Nicolas Saenz Julienne <[email protected]>

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rcu/context-tracking: Move RCU-dynticks internal functions to context_tracking

Move the core RCU eqs/dynticks functions to context tracking so that
we can later merge all that code within context tr

rcu/context-tracking: Move RCU-dynticks internal functions to context_tracking

Move the core RCU eqs/dynticks functions to context tracking so that
we can later merge all that code within context tracking.

Acked-by: Paul E. McKenney <[email protected]>
Signed-off-by: Frederic Weisbecker <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Neeraj Upadhyay <[email protected]>
Cc: Uladzislau Rezki <[email protected]>
Cc: Joel Fernandes <[email protected]>
Cc: Boqun Feng <[email protected]>
Cc: Nicolas Saenz Julienne <[email protected]>
Cc: Marcelo Tosatti <[email protected]>
Cc: Xiongfeng Wang <[email protected]>
Cc: Yu Liao <[email protected]>
Cc: Phil Auld <[email protected]>
Cc: Paul Gortmaker<[email protected]>
Cc: Alex Belits <[email protected]>
Signed-off-by: Paul E. McKenney <[email protected]>
Reviewed-by: Nicolas Saenz Julienne <[email protected]>
Tested-by: Nicolas Saenz Julienne <[email protected]>

show more ...

rcu/context-tracking: Remove rcu_irq_enter/exit()

Now rcu_irq_enter/exit() is an unnecessary middle call between
ct_irq_enter/exit() and nmi_irq_enter/exit(). Take this opportunity
to remove the for

rcu/context-tracking: Remove rcu_irq_enter/exit()

Now rcu_irq_enter/exit() is an unnecessary middle call between
ct_irq_enter/exit() and nmi_irq_enter/exit(). Take this opportunity
to remove the former functions and move the comments above them to the
new entrypoints.

Signed-off-by: Frederic Weisbecker <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Neeraj Upadhyay <[email protected]>
Cc: Uladzislau Rezki <[email protected]>
Cc: Joel Fernandes <[email protected]>
Cc: Boqun Feng <[email protected]>
Cc: Nicolas Saenz Julienne <[email protected]>
Cc: Marcelo Tosatti <[email protected]>
Cc: Xiongfeng Wang <[email protected]>
Cc: Yu Liao <[email protected]>
Cc: Phil Auld <[email protected]>
Cc: Paul Gortmaker<[email protected]>
Cc: Alex Belits <[email protected]>
Signed-off-by: Paul E. McKenney <[email protected]>
Reviewed-by: Nicolas Saenz Julienne <[email protected]>
Tested-by: Nicolas Saenz Julienne <[email protected]>

show more ...

tick/rcu: Remove obsolete rcu_needs_cpu() parameters

With the removal of CONFIG_RCU_FAST_NO_HZ, the parameters in
rcu_needs_cpu() are not necessary anymore. Simply remove them.

Signed-off-by: Frede

tick/rcu: Remove obsolete rcu_needs_cpu() parameters

With the removal of CONFIG_RCU_FAST_NO_HZ, the parameters in
rcu_needs_cpu() are not necessary anymore. Simply remove them.

Signed-off-by: Frederic Weisbecker <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Paul E. McKenney <[email protected]>
Cc: Paul Menzel <[email protected]>

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