Critical section
= Critical section
{wiki}
A region whose accesses must obey a shared <synchronization> protocol. For the <lost update> in <mutual exclusion>, the <critical section> includes the read and the local addition as well as the write. Choosing its boundary means identifying the complete operation whose intermediate state must be protected. Every conflicting access must participate in a compatible protocol; merely declaring a <mutex> does not protect accesses that bypass it.