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From: Jamal Hadi Salim <>
To: Arnaldo Carvalho de Melo <>,
	Peter Zijlstra <>
Cc: Ingo Molnar <>,
	Alexei Starovoitov <>,
	Daniel Borkmann <>,
	Linux Kernel Mailing List <>,
	Linux Networking Development Mailing List 
Subject: Re: [PATCH/RFC] Make perf_event_open() propagate errors for use in bpf_perf_event_open()
Date: Sat, 12 Jan 2019 08:59:41 -0500	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <>

On 2019-01-11 10:55 a.m., Arnaldo Carvalho de Melo wrote:
> Hi Peter,
> 	bpf_perf_event_open() already returns a value, but if
> perf_event_output's output_begin (mostly perf_output_begin) fails,
> the only way to know about that is looking before/after the rb->lost,
> right?
> 	For ring buffer users that is ok, we'll get a PERF_RECORD_LOST,
> etc, but for BPF programs it would be convenient to get that -ENOSPC and
> do some fallback, whatever makes sense, like in my augmented_syscalls
> stuff for 'perf trace', i.e. don't augment it (i.e. push stuff at the
> end of the normal payload), just don't filter the
> raw_syscalls:sys_enter, 'perf trace' will get the enter syscall enter
> event without the pointer dereference at the end, etc, warn the user but
> don't lose a syscall in the strace-like output.	
> 	What do you think? Am I missing something? Probably ;-)
> 	Ah, its just test built.

Works as advertised ;->
Tested-by: Jamal Hadi Salim <>


  reply	other threads:[~2019-01-12 13:59 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-01-11 15:55 Arnaldo Carvalho de Melo
2019-01-11 15:55 ` Arnaldo Carvalho de Melo
2019-01-12 13:59 ` Jamal Hadi Salim [this message]
2019-01-12 13:59   ` Jamal Hadi Salim
2019-01-18 14:52 ` Peter Zijlstra
2019-01-18 15:09   ` Arnaldo Carvalho de Melo
2019-01-18 16:19     ` Peter Zijlstra
2019-01-22 10:17     ` [tip:perf/core] perf: Make perf_event_output() propagate the output() return tip-bot for Arnaldo Carvalho de Melo

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