What is wrong with using inline functions?

Question

While it would be very convenient to use inline functions at some situations,

Are there any drawbacks with inline functions?

Conclusion:

Answer 1

It could increase the size of the executable, and I don't think compilers will always actually make them inline even though you used the inline keyword. (Or is it the other way around, like what Vaibhav said?...)

I think it's usually OK if the function has only 1 or 2 statements.

Edit: Here's what the linux CodingStyle document says about it:

Chapter 15: The inline disease

There appears to be a common misperception that gcc has a magic "make me faster" speedup option called "inline". While the use of inlines can be appropriate (for example as a means of replacing macros, see Chapter 12), it very often is not. Abundant use of the inline keyword leads to a much bigger kernel, which in turn slows the system as a whole down, due to a bigger icache footprint for the CPU and simply because there is less memory available for the pagecache. Just think about it; a pagecache miss causes a disk seek, which easily takes 5 miliseconds. There are a LOT of cpu cycles that can go into these 5 miliseconds.

A reasonable rule of thumb is to not put inline at functions that have more than 3 lines of code in them. An exception to this rule are the cases where a parameter is known to be a compiletime constant, and as a result of this constantness you know the compiler will be able to optimize most of your function away at compile time. For a good example of this later case, see the kmalloc() inline function.

Often people argue that adding inline to functions that are static and used only once is always a win since there is no space tradeoff. While this is technically correct, gcc is capable of inlining these automatically without help, and the maintenance issue of removing the inline when a second user appears outweighs the potential value of the hint that tells gcc to do something it would have done anyway.