From: Nathan Lynch <nathanl@linux•ibm.com>
To: Andrew Donnellan <ajd@linux•ibm.com>, linuxppc-dev@lists•ozlabs.org
Cc: tyreld@linux•ibm.com, nnac123@linux•ibm.com,
ldufour@linux•ibm.com, npiggin@gmail•com
Subject: Re: [PATCH 10/13] powerpc/rtas: improve function information lookups
Date: Mon, 28 Nov 2022 18:08:49 -0600 [thread overview]
Message-ID: <87r0xm8vvy.fsf@linux.ibm.com> (raw)
In-Reply-To: <5b4c4316bfe88a3f231ffe416ce34192189549db.camel@linux.ibm.com>
Andrew Donnellan <ajd@linux•ibm.com> writes:
> On Fri, 2022-11-18 at 09:07 -0600, Nathan Lynch wrote:
>> Convert rtas_token() to use a lockless binary search on the function
>> table. Fall back to the old behavior for lookups against names that
>> are not known to be RTAS functions, but issue a warning. rtas_token()
>> is for function names; it is not a general facility for accessing
>> arbitrary properties of the /rtas node. All known misuses of
>> rtas_token() have been converted to more appropriate of_ APIs in
>> preceding changes.
>
> For in-kernel users, why not go all the way: make rtas_token() static
> and use it purely for the userspace API,
Not sure what userspace API refers to here, can you be more specific? I
don't think rtas_token() is exposed to user space.
> and switch kernel users over
> to using rtas_function_index directly?
Well, I have work in progress to transition all rtas_token() users to a
different API, but using opaque symbolic handles rather than exposing
the indexes. Something like:
/*
* Opaque handle for client code to refer to RTAS functions. All valid
* function handles are build-time constants prefixed with RTAS_FN_.
*/
typedef struct {
enum rtas_function_index index;
} rtas_fn_handle_t;
#define rtas_fn_handle(x_) (const rtas_fn_handle_t) { .index = rtas_fnidx(x_), }
#define RTAS_FN_CHECK_EXCEPTION rtas_fn_handle(CHECK_EXCEPTION)
#define RTAS_FN_DISPLAY_CHARACTER rtas_fn_handle(DISPLAY_CHARACTER)
#define RTAS_FN_EVENT_SCAN rtas_fn_handle(EVENT_SCAN)
...
/**
* rtas_function_token() - RTAS function token lookup.
* @handle: Function handle, e.g. RTAS_FN_EVENT_SCAN.
*
* Context: Any context.
* Return: the token value for the function if implemented by this platform,
* otherwise RTAS_UNKNOWN_SERVICE.
*/
s32 rtas_function_token(const rtas_fn_handle_t handle)
{
const size_t index = handle.index;
const bool out_of_bounds = index >= ARRAY_SIZE(rtas_function_table);
if (WARN_ONCE(out_of_bounds, "invalid function index %zu", index))
return RTAS_UNKNOWN_SERVICE;
return rtas_function_table[index].token;
}
But that's a tree-wide change that would touch various drivers, and I
feel like the current series is what I can reasonably hope to get
applied right now.
next prev parent reply other threads:[~2022-11-29 0:09 UTC|newest]
Thread overview: 49+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-11-18 15:07 [PATCH 00/13] RTAS maintenance Nathan Lynch
2022-11-18 15:07 ` [PATCH 01/13] powerpc/rtas: document rtas_call() Nathan Lynch
2022-11-22 2:46 ` Andrew Donnellan
2022-11-18 15:07 ` [PATCH 02/13] powerpc/rtasd: use correct OF API for event scan rate Nathan Lynch
2022-11-22 2:39 ` Andrew Donnellan
2022-11-18 15:07 ` [PATCH 03/13] powerpc/rtas: avoid device tree lookups in rtas_os_term() Nathan Lynch
2022-11-22 3:03 ` Andrew Donnellan
2022-11-28 18:08 ` Nathan Lynch
2022-11-28 2:29 ` Nicholas Piggin
2022-11-28 18:26 ` Nathan Lynch
2022-11-29 6:45 ` Nicholas Piggin
2022-11-29 15:37 ` Nathan Lynch
2022-11-18 15:07 ` [PATCH 04/13] powerpc/rtas: avoid scheduling " Nathan Lynch
2022-11-22 3:17 ` Andrew Donnellan
2022-11-28 2:34 ` Nicholas Piggin
2022-11-18 15:07 ` [PATCH 05/13] powerpc/pseries/eeh: use correct API for error log size Nathan Lynch
2022-11-22 3:21 ` Andrew Donnellan
2022-11-28 20:22 ` Nathan Lynch
2022-11-18 15:07 ` [PATCH 06/13] powerpc/rtas: clean up rtas_error_log_max initialization Nathan Lynch
2022-11-22 3:40 ` Andrew Donnellan
2022-11-18 15:07 ` [PATCH 07/13] powerpc/rtas: clean up includes Nathan Lynch
2022-11-22 4:45 ` Andrew Donnellan
2022-11-18 15:07 ` [PATCH 08/13] powerpc/rtas: define pr_fmt and convert printk call sites Nathan Lynch
2022-11-22 4:07 ` Andrew Donnellan
2022-11-18 15:07 ` [PATCH 09/13] powerpc/rtas: mandate RTAS syscall filtering Nathan Lynch
2022-11-22 4:20 ` Andrew Donnellan
2022-11-18 15:07 ` [PATCH 10/13] powerpc/rtas: improve function information lookups Nathan Lynch
2022-11-23 2:51 ` Andrew Donnellan
2022-11-23 19:32 ` Nick Child
2022-11-24 3:28 ` Andrew Donnellan
2022-11-28 21:19 ` Nathan Lynch
2022-11-29 0:08 ` Nathan Lynch [this message]
2022-11-29 7:23 ` Andrew Donnellan
2022-11-29 15:33 ` Nathan Lynch
2022-11-23 20:06 ` Nick Child
2022-11-28 21:57 ` Nathan Lynch
2022-11-18 15:07 ` [PATCH 11/13] powerpc/rtas: strengthen do_enter_rtas() type safety, drop inline Nathan Lynch
2022-11-23 3:23 ` Andrew Donnellan
2022-11-28 2:37 ` Nicholas Piggin
2022-11-18 15:07 ` [PATCH 12/13] powerpc/tracing: tracepoints for RTAS entry and exit Nathan Lynch
2022-11-28 2:54 ` Nicholas Piggin
2022-11-18 15:07 ` [PATCH 13/13] powerpc/rtas: place tracepoints in do_enter_rtas() Nathan Lynch
2022-11-28 3:07 ` Nicholas Piggin
2022-11-28 23:44 ` Nathan Lynch
2022-11-29 0:49 ` Michael Ellerman
2022-11-29 20:24 ` Nathan Lynch
2022-11-30 7:43 ` Michael Ellerman
2022-11-29 6:47 ` Nicholas Piggin
2022-12-08 12:40 ` [PATCH 00/13] RTAS maintenance Michael Ellerman
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