linux/kernel/rcu/tree_plugin.h, branch v5.1

Merge branches 'doc.2019.01.26a', 'fixes.2019.01.26a', 'sil.2019.01.26a', 'spdx.2019.02.09a', 'srcu.2019.01.26a' and 'torture.2019.01.26a' into HEAD

2019-02-09T16:47:52Z

doc.2019.01.26a: Documentation updates. fixes.2019.01.26a: Miscellaneous fixes. sil.2019.01.26a: Removal of a few more spin_is_locked() instances. spdx.2019.02.09a: Add SPDX identifiers to RCU files srcu.2019.01.26a: SRCU updates. torture.2019.01.26a: Torture-test updates.

rcu/tree: Convert to SPDX license identifier

2019-02-09T16:44:10Z

Replace the license boiler plate with a SPDX license identifier. While in the area, update an email address. Signed-off-by: Paul E. McKenney [ paulmck: Update .h file SPDX comment format per Joe Perches. ] Reviewed-by: Thomas Gleixner

rcu: Rename rcu_check_callbacks() to rcu_sched_clock_irq()

2019-01-25T23:35:21Z

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: Paul E. McKenney

Merge branches 'consolidate.2019.01.26a' and 'fwd.2019.01.26a' into HEAD

2019-01-25T23:32:01Z

consolidate.2019.01.26a: RCU flavor consolidation cleanups. fwd.2019.01.26a: RCU grace-period forward-progress fixes.

rcu: Update NOCB comments

2019-01-25T23:29:57Z

This commit updates a few obsolete comments in the RCU callback-offload code. Signed-off-by: Paul E. McKenney

rcu: Move rcu_cpu_has_work to rcu_data structure

2019-01-25T23:29:56Z

Given that RCU has a perfectly good per-CPU rcu_data structure, most per-CPU quantities should be stored there. This commit therefore moves the rcu_cpu_has_work per-CPU variable to the rcu_data structure. This also makes this variable unconditionally present, which should be acceptable given the memory reduction due to the RCU flavor consolidation and also due to simplifications this will enable. Signed-off-by: Paul E. McKenney

rcu: Remove unused rcu_cpu_kthread_loops per-CPU variable

2019-01-25T23:29:55Z

The rcu_cpu_kthread_loops variable used to provide debugfs information, but is no longer used. This commit therefore removes it. Signed-off-by: Paul E. McKenney

rcu: Move rcu_cpu_kthread_status to rcu_data structure

2019-01-25T23:29:54Z

Given that RCU has a perfectly good per-CPU rcu_data structure, most per-CPU quantities should be stored there. This commit therefore moves the rcu_cpu_kthread_status per-CPU variable to the rcu_data structure. This also makes this variable unconditionally present, which should be acceptable given the memory reduction due to the RCU flavor consolidation and also due to simplifications this will enable. Signed-off-by: Paul E. McKenney

rcu: Move rcu_cpu_kthread_task to rcu_data structure

2019-01-25T23:29:53Z

Given that RCU has a perfectly good per-CPU rcu_data structure, most per-CPU quantities should be stored there. This commit therefore moves the rcu_cpu_kthread_task per-CPU variable to the rcu_data structure. This also makes this variable unconditionally present, which should be acceptable given the memory reduction due to the RCU flavor consolidation and also due to simplifications this will enable. Signed-off-by: Paul E. McKenney

rcu: Discard separate per-CPU callback counts

2019-01-25T23:28:30Z

Back when there were multiple flavors of RCU, it was necessary to separately count lazy and non-lazy callbacks for each CPU. These counts were used in CONFIG_RCU_FAST_NO_HZ kernels to determine how long a newly idle CPU should be allowed to sleep before handling its RCU callbacks. But now that there is only one flavor, the callback counts for a given CPU's sole rcu_data structure are the counts for that CPU. This commit therefore removes the rcu_data structure's ->nonlazy_posted and ->nonlazy_posted_snap fields, the rcu_idle_count_callbacks_posted() and rcu_cpu_has_callbacks() functions, repurposes the rcu_data structure's ->all_lazy field to record the laziness state at the beginning of the latest idle sojourn, and modifies CONFIG_RCU_FAST_NO_HZ RCU CPU stall warnings accordingly. Signed-off-by: Paul E. McKenney