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Re: [TAPSETS] Linux Kernel Event Trace Tool

From: "Frank Ch. Eigler" <fche at redhat dot com>
To: Mathieu Desnoyers <compudj at krystal dot dyndns dot org>
Cc: systemtap at sourceware dot org
Date: Sun, 18 Dec 2005 14:23:08 -0500
Subject: Re: [TAPSETS] Linux Kernel Event Trace Tool
References: <005c01c60215$fee77bf0$3585b509@IBM946B3A4365F> <20051216161059.GA10472@Krystal> <004301c603d2$e94904d0$4951b509@IBM946B3A4365F> <00f501c603da$b2d93110$4951b509@IBM946B3A4365F> <20051218173434.GA9314@Krystal>

Hi -

On Sun, Dec 18, 2005 at 12:34:34PM -0500, Mathieu Desnoyers wrote:

> [...]  If preemption is not disabled or interrupts disabled, you
> will have issues with _stp_printf.  [...]

Looking in stp_printf for reentrancy prevention is a mistake.  The
reentrancy treatment is supposed to be provided by the probe point
providers: kprobes or the other entry interfacing functions.  (Not all
of them do the right thing yet.)  The runtime functions callable from
probes should assume atomic calls: no reentrancy, no interrupts, and
so on.

- FChE

Follow-Ups:
- Re: [TAPSETS] Linux Kernel Event Trace Tool
  - From: Mathieu Desnoyers

References:
- [TAPSETS] Linux Kernel Event Trace Tool
  - From: Guanglei Li
- Re: [TAPSETS] Linux Kernel Event Trace Tool
  - From: Mathieu Desnoyers
- Re: [TAPSETS] Linux Kernel Event Trace Tool
  - From: Guanglei Li
- Re: [TAPSETS] Linux Kernel Event Trace Tool
  - From: Guanglei Li
- Re: [TAPSETS] Linux Kernel Event Trace Tool
  - From: Mathieu Desnoyers

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