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Re: [RFC 5/5] uprobes: add global breakpoints
- From: Oleg Nesterov <oleg at redhat dot com>
- To: Sebastian Andrzej Siewior <bigeasy at linutronix dot de>
- Cc: linux-kernel at vger dot kernel dot org, x86 at kernel dot org, Peter Zijlstra <a dot p dot zijlstra at chello dot nl>, Arnaldo Carvalho de Melo <acme at ghostprotocols dot net>, Roland McGrath <roland at redhat dot com>, Srikar Dronamraju <srikar at linux dot vnet dot ibm dot com>, Ananth N Mavinakaynahalli <ananth at in dot ibm dot com>, stan_shebs at mentor dot com, gdb-patches at sourceware dot org
- Date: Mon, 13 Aug 2012 15:16:23 +0200
- Subject: Re: [RFC 5/5] uprobes: add global breakpoints
- References: <1344355952-2382-1-git-send-email-bigeasy@linutronix.de> <1344355952-2382-6-git-send-email-bigeasy@linutronix.de> <20120808131457.GA5309@redhat.com> <20120809171802.GB27835@linutronix.de>
On 08/09, Sebastian Andrzej Siewior wrote:
>
> * Oleg Nesterov | 2012-08-08 15:14:57 [+0200]:
>
> >> What I miss right now is an interface to tell the user/gdb that there is a
> >> program that hit a global breakpoint and is waiting for further instructions.
> >> A "tail -f trace" does not work and may contain also a lot of other
> >> informations. I've been thinking about a poll()able file which returns pids of
> >> tasks which are put on hold. Other suggestions?
> >
> >Honestly, I am not sure this is that useful...
>
> How would you notify gdb that there is a new task that hit a breakpoint?
> Or learn yourself?
But why do we need this?
OK, you do not need to convince me, I try to never argue with
new features.
However, I certainly dislike TASK_TRACED in uprobe_wait_traced().
And sleeping in ->handler() is not fair to other consumers.
And I do not think you should modify ptrace_attach() at all.
gdb/user can wakeup the task after PTRACE_ATTACH itself.
Oleg.