Hello everyone, I've got a question about race conditions.
I'm writing the dev.drv and have to share some data between user processes(sys.call) and tasklet.
The shared data is stored in cyclic queue.
My write() sys.call pushing the data to queue and the tasklet pulling the data and writing it to I/O port.
Do I have to use some lock/unlock mechanisms to protect my deque(), enqueue() functions?
The tasklet could be raised by HW INT or from my write() sys.call.
The kernel version is 2.4.32 and the arch. is I386.

Thanks a lot.

Of course, you have to lock it before you read or write into the Queue.

Of course, you have to lock it before you read or write into the queue

Thanks a lot for the answer.. I'll try to add lock/unlock in both enqueue/dequeue functions to solve my problem.
But the question is my basic understanding of 2.4 kernel.
As I understand, the 2.4 kernel series are non-preemtive, which means till one system call is not ended (if we talking about single processor machine), nothing could interrupt the system call except the Hardware interrupt.
So, if in HW INT routine (isr()) noone tries to touch the queue (no enqueue/dequeue calls), this means all other calls to dequeue/enqueue are synchronous. If this is correct, why should I to add synchronizing mechanisms into enqueue/dequeue functions?

yes. you have to prevent some other process to access the queue when your process reading or writing into the queue.