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From: Vince Weaver <vincent.weaver@maine.edu>
To: linux-kernel@vger.kernel.org
Cc: Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@redhat.com>,
	Arnaldo Carvalho de Melo <acme@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	Alexander Shishkin <alexander.shishkin@linux.intel.com>,
	Jiri Olsa <jolsa@redhat.com>, Namhyung Kim <namhyung@kernel.org>
Subject: Re: [perf] perf_event_open() sometimes returning 0
Date: Thu, 2 Jan 2020 14:22:47 -0500 (EST)	[thread overview]
Message-ID: <alpine.DEB.2.21.2001021418590.11372@macbook-air> (raw)
In-Reply-To: <alpine.DEB.2.21.2001021349390.11372@macbook-air>

On Thu, 2 Jan 2020, Vince Weaver wrote:

> so I was tracking down some odd behavior in the perf_fuzzer which turns 
> out to be because perf_even_open() sometimes returns 0 (indicating a file 
> descriptor of 0) even though as far as I can tell stdin is still open.

error is triggered if aux_sample_size has non-zero value.

seems to be this line in kernel/events/core.c:


 if (perf_need_aux_event(event) && !perf_get_aux_event(event, group_leader))
                goto err_locked;


(note, err is never set)


Vince


  reply	other threads:[~2020-01-02 19:22 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-01-02 18:55 Vince Weaver
2020-01-02 19:22 ` Vince Weaver [this message]
2020-01-06 12:03   ` [PATCH] perf: correctly handle failed perf_get_aux_event() (was: Re: [perf] perf_event_open() sometimes returning 0) Mark Rutland
2020-01-06 18:09     ` Vince Weaver
2020-01-16 16:45       ` Vince Weaver
2020-01-18 18:05         ` [PATCH, v5.4] perf: Correctly handle failed perf_get_aux_event() Ingo Molnar
2020-01-19 13:28           ` Greg Kroah-Hartman
2020-01-07  7:39     ` [PATCH] perf: correctly handle failed perf_get_aux_event() (was: Re: [perf] perf_event_open() sometimes returning 0) Alexander Shishkin

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