Synchronization in Linux Kernel Programming

Update: Sep 15: Added RCU Section

What you will learn in this course

• Various concepts related to concurrency like: preemption, context switch, reentrancy, critical section, race condition

• Various Synchronization techniques

  • Per CPU Variables

  • Atomic Variables

  • Spinlocks

  • Semaphores

  • Mutexes

  • Read Write Locks

  • Sequence Locks

  • Read Copy Update(RCU)

  
  

API's/Macros/Structures:

• spinlock_t, DEFINE_SPINLOCK, spin_lock, spin_unlock, spin_trylock, spin_lock_irqsave, spin_unlock_irqrestore,spin_lock_irq, spin_unlock_irq

• atomic_t, atomic64_t, ATOMIC_INIT, atomic_inc, atomic_dec, atomic_set, atomic_read, atomic_add, atomic_sub,

  atomic_dec_and_test, atomic_inc_and_test, atomic_sub_and_test, atomic_add_negative,atomic_add_return, atomic_sub_return, atomic_inc_return, atomic_dec_return,atomic_fetch_add, atomic_fetch_sub, atomic_cmpxchg, atomic_xchg,set_bit, clear_bit, change_bit, test_and_set_bit, test_and_clear_bit, test_and_change_bit,

• NR_CPUS,num_online_cpus,smp_processor_id,get_cpu,put_cpu,DEFINE_PER_CPU,get_cpu_var, put_cpu_var, per_cpu, for_each_online_cpu, alloc_percpu,  free_percpu, per_cpu_ptr

• rcu_read_lock, rcu_read_unlock, synchronize_rcu, call_rcu, rcu_assign_pointer, rcu_dereference

• seqlock_t, seqcount_t, DEFINE_SEQLOCK, seqlock_init, write_seqlock, write_sequnlock

• struct rw_semaphore, DECLARE_RWSEM, init_rwsem, down_read, up_read, down_write, up_write, down_read_trylock, down_write_trylock, downgrade_write

• struct rwlock_t, DEFINE_RWLOCK, rwlock_init, read_lock, read_unlock, write_lock, write_unlock

• struct mutex, DEFINE_MUTEX, mutex_init, mutex_lock, mutex_unlock, mutex_trylock, mutex_lock_interruptible, mutex_unlock_interruptible, mutex_is_locked

• struct semaphore, sema_init, DEFINE_SEMAPHORE, down, up, down_interruptible, down_trylock, down_timeout, down_killable

  
  

Commands used in the course

• nproc

• ps -eaF

• ps aux