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From:   Chuck Lever III <chuck.lever@oracle.com>
To:     Jeff Layton <jlayton@kernel.org>
CC:     Chuck Lever <cel@kernel.org>,
        Linux NFS Mailing List <linux-nfs@vger.kernel.org>
Subject: Re: [PATCH 3/4] SUNRPC: Improve observability in svc_tcp_accept()
Thread-Topic: [PATCH 3/4] SUNRPC: Improve observability in svc_tcp_accept()
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Date:   Mon, 15 May 2023 17:07:21 +0000
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> On May 15, 2023, at 12:54 PM, Jeff Layton <jlayton@kernel.org> wrote:
>=20
> On Mon, 2023-05-15 at 09:32 -0400, Chuck Lever wrote:
>> From: Chuck Lever <chuck.lever@oracle.com>
>>=20
>> The -ENOMEM arm could fire repeatedly if the system runs low on
>> memory, so remove it.
>>=20
>> Don't bother to trace -EAGAIN error events, since those fire after
>> a listener is created (with no work done) and once again after an
>> accept has been handled successfully (again, with no work done).
>>=20
>> Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
>> ---
>> net/sunrpc/svcsock.c |    9 ++-------
>> 1 file changed, 2 insertions(+), 7 deletions(-)
>>=20
>> diff --git a/net/sunrpc/svcsock.c b/net/sunrpc/svcsock.c
>> index e0fb65e90af2..2058641ab9f6 100644
>> --- a/net/sunrpc/svcsock.c
>> +++ b/net/sunrpc/svcsock.c
>> @@ -885,13 +885,8 @@ static struct svc_xprt *svc_tcp_accept(struct svc_x=
prt *xprt)
>> clear_bit(XPT_CONN, &svsk->sk_xprt.xpt_flags);
>> err =3D kernel_accept(sock, &newsock, O_NONBLOCK);
>> if (err < 0) {
>> - if (err =3D=3D -ENOMEM)
>> - printk(KERN_WARNING "%s: no more sockets!\n",
>> -        serv->sv_name);
>> - else if (err !=3D -EAGAIN)
>> - net_warn_ratelimited("%s: accept failed (err %d)!\n",
>> -      serv->sv_name, -err);
>> - trace_svcsock_accept_err(xprt, serv->sv_name, err);
>> + if (err !=3D -EAGAIN)
>> + trace_svcsock_accept_err(xprt, serv->sv_name, err);
>=20
> Would this be better done as a TP_CONDITION tracepoint?

I looked at doing that.

svcsock_accept_err is in a declared class. I would need to
split that into two trace events, one CONDITIONAL and the
other not. svc_tcp_accept() is not a hot path, so it really
isn't worth a whole lot of churn.

Let me know if there's some benefit aside from a bit of
code cleanliness that I forgot.


>> return NULL;
>> }
>> set_bit(XPT_CONN, &svsk->sk_xprt.xpt_flags);
>>=20
>>=20
>=20
> --=20
> Jeff Layton <jlayton@kernel.org>


--
Chuck Lever