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Commit c98cac60 authored by Paul E. McKenney's avatar Paul E. McKenney
Browse files

rcu: Rename rcu_check_callbacks() to rcu_sched_clock_irq() 



The name rcu_check_callbacks() arguably made sense back in the early
2000s when RCU was quite a bit simpler than it is today, but it has
become quite misleading, especially with the advent of dyntick-idle
and NO_HZ_FULL.  The rcu_check_callbacks() function is RCU's hook into
the scheduling-clock interrupt, and is now but one of many ways that
callbacks get promoted to invocable state.

This commit therefore changes the name to rcu_sched_clock_irq(),
which is the same number of characters and clearly indicates this
function's relation to the rest of the Linux kernel.  In addition, for
the sake of consistency, rcu_flavor_check_callbacks() is also renamed
to rcu_flavor_sched_clock_irq().

While in the area, the header comments for both functions are reworked.

Signed-off-by: default avatarPaul E. McKenney <paulmck@linux.ibm.com>
parent 2aa55030

Documentation/RCU/Design/Memory-Ordering/Tree-RCU-Memory-Ordering.html

+2 −2
Original line number Diff line number Diff line
@@ -485,7 +485,7 @@ section that the grace period must wait on. 
noted by <tt>rcu_node_context_switch()</tt> on the left.

On the other hand, if the CPU takes a scheduler-clock interrupt

while executing in usermode, a quiescent state will be noted by

<tt>rcu_check_callbacks()</tt> on the right.

<tt>rcu_sched_clock_irq()</tt> on the right.

Either way, the passage through a quiescent state will be noted

in a per-CPU variable.
@@ -651,7 +651,7 @@ to end. 
These callbacks are identified by <tt>rcu_advance_cbs()</tt>,

which is usually invoked by <tt>__note_gp_changes()</tt>.

As shown in the diagram below, this invocation can be triggered by

the scheduling-clock interrupt (<tt>rcu_check_callbacks()</tt> on

the scheduling-clock interrupt (<tt>rcu_sched_clock_irq()</tt> on

the left) or by idle entry (<tt>rcu_cleanup_after_idle()</tt> on

the right, but only for kernels build with

<tt>CONFIG_RCU_FAST_NO_HZ=y</tt>).

Documentation/RCU/Design/Memory-Ordering/TreeRCU-callback-invocation.svg

+1 −1
Original line number Diff line number Diff line
@@ -349,7 +349,7 @@ 
       font-weight="bold"

       font-size="192"

       id="text202-7-5"

       style="font-size:192px;font-style:normal;font-weight:bold;text-anchor:start;fill:#000000;stroke-width:0.025in;font-family:Courier">rcu_check_callbacks()</text>

       style="font-size:192px;font-style:normal;font-weight:bold;text-anchor:start;fill:#000000;stroke-width:0.025in;font-family:Courier">rcu_sched_clock_irq()</text>

    <rect

       x="7069.6187"

       y="5087.4678"

Documentation/RCU/Design/Memory-Ordering/TreeRCU-gp.svg

+2 −2
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@@ -3902,7 +3902,7 @@ 
         font-style="normal"

         y="-4418.6582"

         x="3745.7725"

         xml:space="preserve">rcu_check_callbacks()</text>

         xml:space="preserve">rcu_sched_clock_irq()</text>

    </g>

    <g

       transform="translate(-850.30204,55463.106)"
@@ -4968,7 +4968,7 @@ 
       font-weight="bold"

       font-size="192"

       id="text202-7-5-19"

       style="font-size:192px;font-style:normal;font-weight:bold;text-anchor:start;fill:#000000;stroke-width:0.025in;font-family:Courier">rcu_check_callbacks()</text>

       style="font-size:192px;font-style:normal;font-weight:bold;text-anchor:start;fill:#000000;stroke-width:0.025in;font-family:Courier">rcu_sched_clock_irq()</text>

    <rect

       x="5314.2671"

       y="82817.688"

Documentation/RCU/Design/Memory-Ordering/TreeRCU-qs.svg

+1 −1
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@@ -775,7 +775,7 @@ 
         font-style="normal"

         y="-4418.6582"

         x="3745.7725"

         xml:space="preserve">rcu_check_callbacks()</text>

         xml:space="preserve">rcu_sched_clock_irq()</text>

    </g>

    <g

       transform="translate(399.7744,828.86448)"

include/linux/rcupdate.h

+1 −1
Original line number Diff line number Diff line
@@ -89,7 +89,7 @@ static inline int rcu_preempt_depth(void) 
/* Internal to kernel */

void rcu_init(void);

extern int rcu_scheduler_active __read_mostly;

void rcu_check_callbacks(int user);

void rcu_sched_clock_irq(int user);

void rcu_report_dead(unsigned int cpu);

void rcutree_migrate_callbacks(int cpu);