Is spinlock a mutex?

Spinlock is a lock which causes a thread trying to acquire it to simply wait in the loop and repeatedly check for its availability. In contrast, a mutex is a program object that is created so that multiple processes can take turns sharing the same resource. Thus, this is the main difference between spinlock and mutex.

Does Linux have mutex?

In the Linux kernel, mutexes refer to a particular locking primitive that enforces serialization on shared memory systems, and not only to the generic term referring to ‘mutual exclusion’ found in academia or similar theoretical text books.

How locks are implemented in Linux?

Two Main Types of Kernel Locks: Spinlocks and Mutexes The fundamental type is the spinlock ( include/asm/spinlock. Spinlocks are very small and fast, and can be used anywhere. The second type is a mutex ( include/linux/mutex. h ): it is like a spinlock, but you may block holding a mutex.

What are the locking mechanisms provided by Linux kernel?

The kernel provides a variety of locking primitives which can be divided into three categories: Sleeping locks. CPU local locks. Spinning locks.

When should one use spinlock instead of mutex?

A hybrid mutex behaves like a spinlock at first on a multi-core system. If a thread cannot lock the mutex, it won’t be put to sleep immediately, since the mutex might get unlocked pretty soon, so instead the mutex will first behave exactly like a spinlock.

How does Linux mutex work?

The idea behind mutexes is to only allow one thread access to a section of memory at any one time. If one thread locks the mutex, any other lock attempts will block until the first one unlocks.

Where is spinlock used in Linux kernel?

If you use spin_lock(), the process could be interrupted in the locked section of code. To release a spin_lock after executing the critical section of code, you need to call spin_unlock() or spin_unlock_irqrestore().

What is spinlock recursion?

The “spinlock” is a register of the current pid, plus a recursion counter, with atomic access. The pid is either -1 (unset, count is zero) or some decent value (count is positive). The trylock will succeed and set the pid if it is currently unset.

How do you stop a spinlock?

There are two ways to avoid this:

1. Do not acquire the lock. In many situations it is possible to design data structures that do not require locking, e.g. by using per-thread or per-CPU data and disabling interrupts.
2. Switch to a different thread while waiting.