On Mon, 6 May 2019 18:34:59 -0700 Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> wrote: > On Mon, May 6, 2019 at 6:04 PM Steven Rostedt <rostedt@xxxxxxxxxxx> wrote: > > > > That iterator does something special for each individual record. All > > 40,000 of them. > > .. yes, but the 'int3' only happens for *one* of them at a time. > > Why would it bother with the other 39,999 calls? > > You could easily just look up the record at the int3 time, and just > use the record. Exactly the same way you use the one-at-a-time ones. > > Instead, you emulate a fake call to a function that *wouldn't* get > called, which now does the lookup there. That's the part I don't get. > Why are you emulating something else than what you'd be rewriting? > Ah, now I see what you are saying. Yes, I could pass in what it is suppose to call. But I was trying to use the same code for all the alternative solutions we were passing around, and this became the "default" case that would work with any int3_emulate_call implementation we came up with. That is, if we call ftrace_regs_caller() for any scenario it should work. Even if the call was suppose to be a nop, because in that case, all the ftrace_ops registered in the iterator would refuse to have their handler be called for that function. I sent you a single patch, but that was really just a diff of several applied patches against your unmodified tree. The last patch implements the ftrace code. And I had it this way because it should work for any of the implementations. I could modify it so that it picks what function to call when the int3 is triggered. I think all the solutions we are down to allow that now. Some of the early ideas had me call one function for all int3s due to trampolines and such. Also, I figured just calling ftrace_regs_caller() was simpler then having that int3 handler do the hash look ups to determine what handler it needs to call. -- Steve
