RCU Handbook

• Review Checklist for RCU Patches
• RCU and lockdep checking
• Lockdep-RCU Splat
• RCU and Unloadable Modules
  • Unloading Modules That Use call_rcu()
  • rcu_barrier()
  • Implementing rcu_barrier()
  • rcu_barrier() Summary
  • Answers to Quick Quizzes
• PROPER CARE AND FEEDING OF RETURN VALUES FROM rcu_dereference()
  • EXAMPLE OF AMPLIFIED RCU-USAGE BUG
  • EXAMPLE WHERE THE COMPILER KNOWS TOO MUCH
  • WHICH MEMBER OF THE rcu_dereference() FAMILY SHOULD YOU USE?
  • SPARSE CHECKING OF RCU-PROTECTED POINTERS
• What is RCU? -- “Read, Copy, Update”
  • 1. RCU OVERVIEW
  • 2. WHAT IS RCU’S CORE API?
  • 3. WHAT ARE SOME EXAMPLE USES OF CORE RCU API?
  • 4. WHAT IF MY UPDATING THREAD CANNOT BLOCK?
  • 5. WHAT ARE SOME SIMPLE IMPLEMENTATIONS OF RCU?
  • 6. ANALOGY WITH READER-WRITER LOCKING
  • 7. ANALOGY WITH REFERENCE COUNTING
  • 8. FULL LIST OF RCU APIs
  • 9. ANSWERS TO QUICK QUIZZES
• RCU Concepts
  • Frequently Asked Questions
• Using RCU hlist_nulls to protect list and objects
  • Using ‘nulls’
  • Avoiding extra smp_rmb()
• Reference-count design for elements of lists/arrays protected by RCU
• RCU Torture Test Operation
  • CONFIG_RCU_TORTURE_TEST
  • Output
  • Usage on Specific Kernel Builds
  • Usage on Mainline Kernels
  • Repeated Runs
  • Distributed Runs
• Using RCU’s CPU Stall Detector
  • What Causes RCU CPU Stall Warnings?
  • Fine-Tuning the RCU CPU Stall Detector
  • Interpreting RCU’s CPU Stall-Detector “Splats”
  • Multiple Warnings From One Stall
  • Stall Warnings for Expedited Grace Periods
  • RCU_CPU_STALL_CPUTIME
• Using RCU to Protect Read-Mostly Linked Lists
  • Example 1: Read-mostly list: Deferred Destruction
  • Example 2: Read-Side Action Taken Outside of Lock: No In-Place Updates
  • Example 3: Handling In-Place Updates
  • Example 4: Eliminating Stale Data
  • Example 5: Skipping Stale Objects
  • Summary
• Using RCU to Protect Dynamic NMI Handlers
• RCU on Uniprocessor Systems
  • Example 1: softirq Suicide
  • Example 2: Function-Call Fatality
  • Example 3: Death by Deadlock
  • Summary
• A Tour Through TREE_RCU’s Grace-Period Memory Ordering
  • Introduction
  • What Is Tree RCU’s Grace Period Memory Ordering Guarantee?
  • Tree RCU Grace Period Memory Ordering Building Blocks
• A Tour Through TREE_RCU’s Expedited Grace Periods
  • Introduction
  • Expedited Grace Period Design
  • RCU-preempt Expedited Grace Periods
• A Tour Through RCU’s Requirements
  • Introduction
  • Fundamental Requirements
  • Fundamental Non-Requirements
  • Parallelism Facts of Life
  • Quality-of-Implementation Requirements
  • Software-Engineering Requirements
  • Linux Kernel Complications
  • Other RCU Flavors
  • Possible Future Changes
  • Summary
  • Acknowledgments
• A Tour Through TREE_RCU’s Data Structures [LWN.net]
  • Introduction
  • Data-Structure Relationships