Can anybody please tell me, what exactly does synchronize_net() function do in LINUX? More specifically, what's the effect of this function if I run regular traffic, or if I run traffic using a packet generator from within the driver itself (so I don't pass all the kernel network stack?

Thank you,
Mark

It's a barrier operation. After returning, all packet queue operations (which are lockless rcu for performance) will be up to date with respect to operations before the call.

https://lwn.net/Articles/262464/

Thank you, smallpond.

Can you give more details on what exactly this function does?
More precisely, what happens if I run traffic, and in the driver some process calls this function?

Thank you,
Mark

Well, have you(!) read the entirety of the cited article, and did you read it (several times ...) thoroughly?

Then, did you look at the corresponding Linux source code? (For your particular architecture and distro?)

I like to use the term, "lazy synchronization," to describe this particular networking function. In high-volume, high-performance situations, "close synchronization" is expensive and often unnecessary. To the extent that it is necessary, it is often the case that just a particular process needs to "synchronize with" some subset of the packets that are passing through, so as to synchronize its activities with respect to its clientele.