netdev - Re: [PATCH net] xdp: xdp_mem_allocator can be NULL in trace_mem

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Date:   Mon, 07 Mar 2022 19:07:37 +0100
From:   Toke Høiland-Jørgensen <toke@...hat.com>
To:     Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Cc:     netdev@...r.kernel.org, bpf@...r.kernel.org,
        Alexei Starovoitov <ast@...nel.org>,
        Andrii Nakryiko <andrii@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        "David S. Miller" <davem@...emloft.net>,
        Ingo Molnar <mingo@...hat.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Jesper Dangaard Brouer <hawk@...nel.org>,
        John Fastabend <john.fastabend@...il.com>,
        KP Singh <kpsingh@...nel.org>, Martin KaFai Lau <kafai@...com>,
        Song Liu <songliubraving@...com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Yonghong Song <yhs@...com>
Subject: Re: [PATCH net] xdp: xdp_mem_allocator can be NULL in
 trace_mem_connect().

Sebastian Andrzej Siewior <bigeasy@...utronix.de> writes:

> On 2022-03-07 17:50:04 [+0100], Toke Høiland-Jørgensen wrote:
>> 
>> Right, looking at the code again, the id is only assigned in the path
>> that doesn't return NULL from __xdp_reg_mem_model().
>> 
>> Given that the trace points were put in specifically to be able to pair
>> connect/disconnect using the IDs, I don't think there's any use to
>> creating the events if there's no ID, so I think we should fix it by
>> skipping the trace event entirely if xdp_alloc is NULL.
>
> This sounds like a reasonable explanation. If nobody disagrees then I
> post a new patch tomorrow and try to recycle some of what you wrote :)

SGTM :)

-Toke