Messages in this thread | | | Date | Mon, 3 Apr 2023 07:04:43 -0700 | From | Boqun Feng <> | Subject | Re: [PATCH 03/13] rust: lock: introduce `Mutex` |
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On Mon, Apr 03, 2023 at 10:20:52AM +0200, Peter Zijlstra wrote: > On Thu, Mar 30, 2023 at 11:47:12AM -0700, Boqun Feng wrote: > > On Thu, Mar 30, 2023 at 03:01:08PM +0200, Peter Zijlstra wrote: > > > On Thu, Mar 30, 2023 at 01:39:44AM -0300, Wedson Almeida Filho wrote: > > > > From: Wedson Almeida Filho <walmeida@microsoft.com> > > > > > > > > This is the `struct mutex` lock backend and allows Rust code to use the > > > > kernel mutex idiomatically. > > > > > > What, if anything, are the plans to support the various lockdep > > > annotations? Idem for the spinlock thing in the other patch I suppose. > > > > FWIW: > > > > * At the init stage, SpinLock and Mutex in Rust use initializers > > that are aware of the lockdep, so everything (lockdep_map and > > lock_class) is all set up. > > > > * At acquire or release time, Rust locks just use ffi to call C > > functions that have lockdep annotations in them, so lockdep > > should just work. > > > > ffi is what the C++ world calls RAII ? >
ffi is foreign function interface, it means calling a C function from Rust. Sorry if I make things confusing ;-)
> But yes, I got that far, but I wondered about things like > spin_lock_nested(&foo, SINGLE_DEPTH_NESTING) and other such 'advanced' > annotations. >
Right, I haven't really thought through them, but I think it's easy to add them later (famous later words).
> Surely we're going to be needing them at some point. I suppose you can > do the single depth nesting one with a special guard type (or whatever > you call that in the rust world) ?
or a different method for Lock:
impl Lock { // implementation block for type `Lock` // v function is called via a.lock_nested(SINGLE_DEPTH_NESTING), a is a Lock fn lock_nested(&self, level: i32) -> Guard<..> { // ^ defines a function ^ returns a guard
.. } }
since Rust side just uses the same function to unlock as C side, so a normal Guard type suffices, because we don't treat nested lock differently at unlock time. But if we were to add some more checking at compile time, we could have a slight different Guard or something.
Regards, Boqun
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