6 ms·

This won't work for: 1. Larger than word size variables 2. Out of order CPUs 3. On multicore CPUs when another core handles the signal Atomics must be used

• kazinator 3y ago
  This existed before threads were introduced into the C language. It's only about a single control flow being interrupted by signal, remaining suspended while the handler executes. As soon as the suspended code resumes, the updated sig_atomic_t value is visible to it, and the whole value (not some torn mix of the old a new value). It has nothing to do with threads or cores; if one thread runs a handler and another looks at the flag, it's not even relevant that a signal handler is involved. The sig_atomic_t type that is specified for that purpose and must be used, which rules out the uncertainty you're referring to in (1). It is not a type qualifier but a specifier.