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Message-ID: <20240913093201.GA19305@redhat.com>
Date: Fri, 13 Sep 2024 11:32:01 +0200
From: Oleg Nesterov <oleg@...hat.com>
To: Jiri Olsa <olsajiri@...il.com>
Cc: Peter Zijlstra <peterz@...radead.org>,
Alexei Starovoitov <ast@...nel.org>,
Daniel Borkmann <daniel@...earbox.net>,
Andrii Nakryiko <andrii@...nel.org>, bpf@...r.kernel.org,
Martin KaFai Lau <kafai@...com>, Song Liu <songliubraving@...com>,
Yonghong Song <yhs@...com>,
John Fastabend <john.fastabend@...il.com>,
KP Singh <kpsingh@...omium.org>,
Stanislav Fomichev <sdf@...gle.com>, Hao Luo <haoluo@...gle.com>,
Steven Rostedt <rostedt@...dmis.org>,
Masami Hiramatsu <mhiramat@...nel.org>,
linux-kernel@...r.kernel.org, linux-trace-kernel@...r.kernel.org
Subject: Re: [PATCHv3 1/7] uprobe: Add support for session consumer
On 09/13, Jiri Olsa wrote:
>
> On Thu, Sep 12, 2024 at 06:35:39PM +0200, Oleg Nesterov wrote:
> > > list_for_each_entry_srcu(uc, &uprobe->consumers, cons_node,
> > > srcu_read_lock_held(&uprobes_srcu)) {
> > > + /*
> > > + * If we don't find return consumer, it means uprobe consumer
> > > + * was added after we hit uprobe and return consumer did not
> > > + * get registered in which case we call the ret_handler only
> > > + * if it's not session consumer.
> > > + */
> > > + ric = return_consumer_find(ri, &iter, uc->id);
> > > + if (!ric && uc->session)
> > > + continue;
> > > if (uc->ret_handler)
> > > - uc->ret_handler(uc, ri->func, regs);
> > > + uc->ret_handler(uc, ri->func, regs, ric ? &ric->cookie : NULL);
> >
> > So why do we need the new uc->session member and the uc->session above ?
> >
> > If return_consumer_find() returns NULL, uc->ret_handler(..., NULL) can handle
> > this case itself?
>
> I tried to explain that in the comment above.. we do not want to
> execute session ret_handler at all in this case, because its entry
> counterpart did not run
I understand, but the session ret_handler(..., __u64 *data) can simply do
// my ->handler() didn't run or it didn't return 0
if (!data)
return;
at the start?
Oleg.
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