rcu: Make call_rcu() lazy only when CONFIG_RCU_LAZY is enabled

[kernel-patches-bot]

Pull request for series with
subject: rcu: Make call_rcu() lazy only when CONFIG_RCU_LAZY is enabled
version: 1
url: https://patchwork.kernel.org/project/rcu/list/?series=686650

[kernel-patches-bot]

Master branch: 00c153b
series: https://patchwork.kernel.org/project/rcu/list/?series=686650
version: 1

Pull request is NOT updated. Failed to apply https://patchwork.kernel.org/project/rcu/list/?series=686650
error message:

Cmd('git') failed due to: exit code(128)
  cmdline: git am -3
  stdout: 'Applying: rcu: Make call_rcu() lazy only when CONFIG_RCU_LAZY is enabled
Using index info to reconstruct a base tree...
M	kernel/rcu/tree.c
Falling back to patching base and 3-way merge...
Auto-merging kernel/rcu/tree.c
CONFLICT (content): Merge conflict in kernel/rcu/tree.c
Patch failed at 0001 rcu: Make call_rcu() lazy only when CONFIG_RCU_LAZY is enabled
When you have resolved this problem, run "git am --continue".
If you prefer to skip this patch, run "git am --skip" instead.
To restore the original branch and stop patching, run "git am --abort".'
  stderr: 'error: Failed to merge in the changes.
hint: Use 'git am --show-current-patch=diff' to see the failed patch'

conflict:

diff --cc kernel/rcu/tree.c
index 282002e62cf3,97ef602da3d5..000000000000
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@@ -2851,9 -2812,91 +2851,95 @@@ void call_rcu(struct rcu_head *head, rc
  		local_irq_restore(flags);
  	}
  }
++<<<<<<< HEAD
++=======
+ 
+ #ifdef CONFIG_RCU_LAZY
+ /**
+  * call_rcu_flush() - Queue RCU callback for invocation after grace period, and
+  * flush all lazy callbacks (including the new one) to the main ->cblist while
+  * doing so.
+  *
+  * @head: structure to be used for queueing the RCU updates.
+  * @func: actual callback function to be invoked after the grace period
+  *
+  * The callback function will be invoked some time after a full grace
+  * period elapses, in other words after all pre-existing RCU read-side
+  * critical sections have completed.
+  *
+  * Use this API instead of call_rcu() if you don't want the callback to be
+  * invoked after very long periods of time, which can happen on systems without
+  * memory pressure and on systems which are lightly loaded or mostly idle.
+  * This function will cause callbacks to be invoked sooner than later at the
+  * expense of extra power. Other than that, this function is identical to, and
+  * reuses call_rcu()'s logic. Refer to call_rcu() for more details about memory
+  * ordering and other functionality.
+  */
+ void call_rcu_flush(struct rcu_head *head, rcu_callback_t func)
+ {
+ 	return __call_rcu_common(head, func, false);
+ }
+ EXPORT_SYMBOL_GPL(call_rcu_flush);
+ 
+ /**
+  * call_rcu() - Queue an RCU callback for invocation after a grace period.
+  * By default the callbacks are 'lazy' and are kept hidden from the main
+  * ->cblist to prevent starting of grace periods too soon.
+  * If you desire grace periods to start very soon, use call_rcu_flush().
+  *
+  * @head: structure to be used for queueing the RCU updates.
+  * @func: actual callback function to be invoked after the grace period
+  *
+  * The callback function will be invoked some time after a full grace
+  * period elapses, in other words after all pre-existing RCU read-side
+  * critical sections have completed.  However, the callback function
+  * might well execute concurrently with RCU read-side critical sections
+  * that started after call_rcu() was invoked.
+  *
+  * RCU read-side critical sections are delimited by rcu_read_lock()
+  * and rcu_read_unlock(), and may be nested.  In addition, but only in
+  * v5.0 and later, regions of code across which interrupts, preemption,
+  * or softirqs have been disabled also serve as RCU read-side critical
+  * sections.  This includes hardware interrupt handlers, softirq handlers,
+  * and NMI handlers.
+  *
+  * Note that all CPUs must agree that the grace period extended beyond
+  * all pre-existing RCU read-side critical section.  On systems with more
+  * than one CPU, this means that when "func()" is invoked, each CPU is
+  * guaranteed to have executed a full memory barrier since the end of its
+  * last RCU read-side critical section whose beginning preceded the call
+  * to call_rcu().  It also means that each CPU executing an RCU read-side
+  * critical section that continues beyond the start of "func()" must have
+  * executed a memory barrier after the call_rcu() but before the beginning
+  * of that RCU read-side critical section.  Note that these guarantees
+  * include CPUs that are offline, idle, or executing in user mode, as
+  * well as CPUs that are executing in the kernel.
+  *
+  * Furthermore, if CPU A invoked call_rcu() and CPU B invoked the
+  * resulting RCU callback function "func()", then both CPU A and CPU B are
+  * guaranteed to execute a full memory barrier during the time interval
+  * between the call to call_rcu() and the invocation of "func()" -- even
+  * if CPU A and CPU B are the same CPU (but again only if the system has
+  * more than one CPU).
+  *
+  * Implementation of these memory-ordering guarantees is described here:
+  * Documentation/RCU/Design/Memory-Ordering/Tree-RCU-Memory-Ordering.rst.
+  */
+ void call_rcu(struct rcu_head *head, rcu_callback_t func)
+ {
+ 	return __call_rcu_common(head, func, true);
+ }
++>>>>>>> rcu: Make call_rcu() lazy only when CONFIG_RCU_LAZY is enabled
  EXPORT_SYMBOL_GPL(call_rcu);
+ #else
+ void call_rcu(struct rcu_head *head, rcu_callback_t func)
+ {
+ 	return __call_rcu_common(head, func, false);
+ }
+ EXPORT_SYMBOL_GPL(call_rcu);
+ #endif
  
 +
  /* Maximum number of jiffies to wait before draining a batch. */
  #define KFREE_DRAIN_JIFFIES (5 * HZ)
  #define KFREE_N_BATCHES 2

[kernel-patches-bot]

Master branch: fa70e60
series: https://patchwork.kernel.org/project/rcu/list/?series=686936
version: 3

[kernel-patches-bot]

Master branch: fa70e60
series: https://patchwork.kernel.org/project/rcu/list/?series=686936
version: 3

[kernel-patches-bot]

Master branch: fa70e60
series: https://patchwork.kernel.org/project/rcu/list/?series=686936
version: 3

[kernel-patches-bot]

Master branch: fa70e60
series: https://patchwork.kernel.org/project/rcu/list/?series=686936
version: 3

[kernel-patches-bot]

Master branch: fa70e60
series: https://patchwork.kernel.org/project/rcu/list/?series=686936
version: 3

[kernel-patches-bot]

Master branch: fa70e60
series: https://patchwork.kernel.org/project/rcu/list/?series=686936
version: 3

[kernel-patches-bot]

Master branch: fa70e60
series: https://patchwork.kernel.org/project/rcu/list/?series=686936
version: 3

[kernel-patches-bot]

Master branch: fa70e60
series: https://patchwork.kernel.org/project/rcu/list/?series=686936
version: 3

[kernel-patches-bot]

Master branch: fa70e60
series: https://patchwork.kernel.org/project/rcu/list/?series=686936
version: 3

[kernel-patches-bot]

Master branch: fa70e60
series: https://patchwork.kernel.org/project/rcu/list/?series=686936
version: 3

[kernel-patches-bot]

Master branch: fa70e60
series: https://patchwork.kernel.org/project/rcu/list/?series=686936
version: 3

[kernel-patches-bot]

Master branch: fa70e60
series: https://patchwork.kernel.org/project/rcu/list/?series=686936
version: 3

[kernel-patches-bot]

Master branch: fa70e60
series: https://patchwork.kernel.org/project/rcu/list/?series=686936
version: 3

[kernel-patches-bot]

Master branch: fa70e60
series: https://patchwork.kernel.org/project/rcu/list/?series=686936
version: 3