Messages in this thread | | | Date | Thu, 25 Nov 2021 16:56:16 +0000 | From | Qais Yousef <> | Subject | Re: [PATCH] sched/core: Export pelt_thermal_tp |
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Hi Peter
On 10/28/21 18:50, Peter Zijlstra wrote: > On Thu, Oct 28, 2021 at 09:22:05AM -0700, Christoph Hellwig wrote: > > On Thu, Oct 28, 2021 at 06:18:55PM +0200, Peter Zijlstra wrote: > > > > > @@ -36,6 +36,7 @@ EXPORT_TRACEPOINT_SYMBOL_GPL(pelt_rt_tp); > > > > > EXPORT_TRACEPOINT_SYMBOL_GPL(pelt_dl_tp); > > > > > EXPORT_TRACEPOINT_SYMBOL_GPL(pelt_irq_tp); > > > > > EXPORT_TRACEPOINT_SYMBOL_GPL(pelt_se_tp); > > > > > +EXPORT_TRACEPOINT_SYMBOL_GPL(pelt_thermal_tp); > > > > > EXPORT_TRACEPOINT_SYMBOL_GPL(sched_cpu_capacity_tp); > > > > > EXPORT_TRACEPOINT_SYMBOL_GPL(sched_overutilized_tp); > > > > > EXPORT_TRACEPOINT_SYMBOL_GPL(sched_util_est_cfs_tp); > > > > > > > > ... and while we're at it, all these exports are unused and should > > > > be deleted as well. > > > > > > This is my concession wrt tracepoints. Actual tracepoints are ABI, > > > exports are in-kernel interfaces and are explicitly not ABI. > > > > > > This way people can use an external module to get at the tracepoint data > > > without having in-tree tracepoints. > > > > All of this makes no sense at all. These are entirely dead exports. > > If you remove them nothing else changes. Note taht the tracepoints > > do have in-kernel callers, so if people thing of them as an ABI you've > > got your ABI already with or without the exports. > > These are not normal traceevents, these are tracepoints, the distinction > is that these things do not show up in tracefs and there is no userspace > visible representation of them. No userspace gives no ABI. > > All they provide is the in-code hook and in-kernel registration > interface. These EXPORTS export that registration interface, such that > an out-of-tree module can make use of them. > > And yes, unused exports are iffy, out-of-tree modules are iffy, but in > this case I made an exception since ABI contraints are worse. We very > clearly state there is no such thing is kabi, so breaking any user of > these exports if fair game. > > Breaking users of userspace trace-events gets kernel patches reverted > (been there, done that, never want to ever be there again). > > People want to trace this stuff, but I *REALLY* do not want to commit to > ABI, this is the middle-ground that sucks least :/
AFAICS this wasn't picked up. Should I tweak the commit message to make things clearer?
Thanks!
-- Qais Yousef
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