Linus 对 Rust 进内核给出了珍贵的指导意见
So I replied with my reactions to a couple of the individual patches, but on the whole I don't hate it.
HOWEVER.
I do think that the "run-time failure panic" is a fundamental issue.
I may not understand the ramifications of when it can happen, so maybe it's less of an issue than I think it is, but very fundamentally I think that if some Rust allocation can cause a panic, this is simply fundamentally not acceptable.
Allocation failures in a driver or non-core code and that is by definition all of any new Rust code can never EVER validly cause panics. Same goes for "oh, some case I didn't test used 128-bit integers or floating point".
So if the Rust compiler causes hidden allocations that cannot be caught and returned as errors, then I seriously think that this whole approach needs to be entirely NAK'ed, and the Rust infrastructure - whether at the compiler level or in the kernel wrappers - needs more work.
So if the panic was just some placeholder for things that _can_ be caught, then I think that catching code absolutely needs to be written, and not left as a to-do.
And if the panic situation is some fundamental "this is what the Rust compiler does for internal allocation failures", then I think it needs more than just kernel wrapper work - it needs the Rust compiler to be *fixed*.
Because kernel code is different from random user-space system tools. Running out of memory simply MUST NOT cause an abort. It needs to just result in an error return.
I don't know enough about how the out-of-memory situations would be triggered and caught to actually know whether this is a fundamental problem or not, so my reaction comes from ignorance, but basically the rule has to be that there are absolutely zero run-time "panic()" calls. Unsafe code has to either be caught at compile time, or it has to be handled dynamically as just a regular error.
With the main point of Rust being safety, there is no way I will ever accept "panic dynamically" (whether due to out-of-memory or due to anything else - I also reacted to the "floating point use causes dynamic panics") as a feature in the Rust model.
Linus
详细：https://lkml.org/lkml/2021/4/14/1099
So I replied with my reactions to a couple of the individual patches, but on the whole I don't hate it.
HOWEVER.
I do think that the "run-time failure panic" is a fundamental issue.
I may not understand the ramifications of when it can happen, so maybe it's less of an issue than I think it is, but very fundamentally I think that if some Rust allocation can cause a panic, this is simply fundamentally not acceptable.
Allocation failures in a driver or non-core code and that is by definition all of any new Rust code can never EVER validly cause panics. Same goes for "oh, some case I didn't test used 128-bit integers or floating point".
So if the Rust compiler causes hidden allocations that cannot be caught and returned as errors, then I seriously think that this whole approach needs to be entirely NAK'ed, and the Rust infrastructure - whether at the compiler level or in the kernel wrappers - needs more work.
So if the panic was just some placeholder for things that _can_ be caught, then I think that catching code absolutely needs to be written, and not left as a to-do.
And if the panic situation is some fundamental "this is what the Rust compiler does for internal allocation failures", then I think it needs more than just kernel wrapper work - it needs the Rust compiler to be *fixed*.
Because kernel code is different from random user-space system tools. Running out of memory simply MUST NOT cause an abort. It needs to just result in an error return.
I don't know enough about how the out-of-memory situations would be triggered and caught to actually know whether this is a fundamental problem or not, so my reaction comes from ignorance, but basically the rule has to be that there are absolutely zero run-time "panic()" calls. Unsafe code has to either be caught at compile time, or it has to be handled dynamically as just a regular error.
With the main point of Rust being safety, there is no way I will ever accept "panic dynamically" (whether due to out-of-memory or due to anything else - I also reacted to the "floating point use causes dynamic panics") as a feature in the Rust model.
Linus
详细：https://lkml.org/lkml/2021/4/14/1099
