First when referring to line numbers of code you need to add the actual (FreeRTOS) version of that code 
But I can’t say much about the implementation of xQueueGenericSend anyway.
The concept of critical sections was recently very well explained by Richard Damon here in the forum.
When using critical sections you must be aware that it affects your (worst case) interrupt response time. That means an ISR of a hardware interrupt might get delayed because all interrupts are disabled while executing code inside a critical section.
That’s the benefit of just suspending all tasks. Interrupts remain enabled and get handled by their corresponding ISRs.
There is no common rule how long ‘very short’ is. It depends on the (real-time) requirements of your application.
Both protection methods are very light weight and fast, but affect the whole application i.e. all tasks regardless of their priorities.
In general you should narrow down the scope of any protection as much as possible. So when protecting the access to some data used by only 3 tasks out of 5 in your application, it’s almost always better to use a mutex used by these 3 tasks and all other tasks are not affected.
Also mutexes take the task priorities into account to decide which of the maybe blocked other tasks get’s the mutex next when it gets released by the task currently holding it.
How to choose a critical section protecton approach? taskENTER_CRITICAL or vTaskSuspendAll or mutex?
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