Consider the following code
int Var;
Function1() {
[CS_Start]
Var++;
[CS_End]
}
Function2() {
[CS_Start]
Var += 2;
[CS_End]
}
ISR() {
[CS_Start]
Var--;
[CS_End]
}
How to protect Var in multitasking environment? One of the design I understand is to keep Var as volatile such that it is safe in multiprocessor scheduling scheme. Additionally Spin lock (in place of mutex) can be implemented to protect the critical section.
What happens if Spinlock is acquired by Function1 and ISR occurs (with higher priority than scheduler timer) ISR will keep on polling and Function1 never gets a chance to release the lock. Any solution to this problem ?
