Re: Question regarding mutex locking

[Larry Finger]

Andreas Schwab wrote:
> Larry Finger <Larry.Finger@xxxxxxxxxxxx> writes:
> 
>> If a particular routine needs to lock a mutex, but it may be entered with that mutex already locked,
>> would the following code be SMP safe?
>>
>> hold_lock = mutex_trylock()
>>
>> ...
>>
>> if (hold_lock)
>> 	mutex_unlock()
> 
> When two CPUs may enter the critical region at the same time, what is
> the point of the mutex?  Also, the first CPU may unlock the mutex while
> the second one is still inside the critical region.

Thank you for that answer. I think that I'm finally beginning to understand.

Larry
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