Tag Archives: Priority Ceiling Protocol

Mutex vs. Semaphores – Part 3 (final part): Mutual Exclusion Problems

Niall Cooling

Director at Feabhas Limited
Co-Founder and Director of Feabhas since 1995.
Niall has been designing and programming embedded systems for over 30 years. He has worked in different sectors, including aerospace, telecomms, government and banking.
His current interest lie in IoT Security and Agile for Embedded Systems.

As hopefully you can see from the previous posting, the mutex is a significantly safer mechanism to use for implementing mutual exclusion around shared resources. Nevertheless, there are still a couple of problems that use of the mutex (in preference to the semaphore) will not solve. These are:

Circular deadlock
Non-cooperation

Circular Deadlock
Circular deadlock, often referred to as the “deadly embrace” problem is a condition where two or more tasks develop a circular dependency of mutual exclusion. Simply put, one task is blocked […]

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