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[34.85.235.172]) by smtp.gmail.com with ESMTPSA id 956f58d0204a3-667874c2d15sm1014291d50.0.2026.07.07.08.18.59 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 07 Jul 2026 08:18:59 -0700 (PDT) Date: Tue, 07 Jul 2026 11:18:54 -0400 From: Willem de Bruijn To: luyun , Willem de Bruijn , davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, horms@kernel.org, kerneljasonxing@gmail.com, kuniyu@google.com Cc: mhal@rbox.co, bjorn@kernel.org, jiayuan.chen@linux.dev, netdev@vger.kernel.org, minhnguyen.080505@gmail.com Message-ID: In-Reply-To: References: <20260706100229.13812-1-luyun_611@163.com> Subject: Re: [PATCH net-next] net: skbuff: use net_zcopy_get() instead of refcount_inc() Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable luyun wrote: > = > =E5=9C=A8 2026/7/6 21:55, Willem de Bruijn =E5=86=99=E9=81=93: > > Yun Lu wrote: > >> From: Yun Lu > >> > >> The net_zcopy_get() increments the uarg->refcnt, which is called bot= h > >> in pskb_carve_inside_header() and pskb_carve_inside_nonlinear(). > >> Also use net_zcopy_get() in pskb_expand_head for code consistency. > >> > >> No functional change intended. > >> > >> Signed-off-by: Yun Lu > >> --- > >> net/core/skbuff.c | 2 +- > >> 1 file changed, 1 insertion(+), 1 deletion(-) > >> > >> diff --git a/net/core/skbuff.c b/net/core/skbuff.c > >> index 18dabb4e9cfa..bcf3b2c65fb9 100644 > >> --- a/net/core/skbuff.c > >> +++ b/net/core/skbuff.c > >> @@ -2326,7 +2326,7 @@ int pskb_expand_head(struct sk_buff *skb, int = nhead, int ntail, > >> if (skb_orphan_frags(skb, gfp_mask)) > >> goto nofrags; > >> if (skb_zcopy(skb)) > >> - refcount_inc(&skb_uarg(skb)->refcnt); > >> + net_zcopy_get(skb_zcopy(skb)); > > This adds some unnecessary instructions in skb_zcopy. > > > > It's not terrible and I see the consistency argument. But would make > > more sense to update the recently added pskb_carve_.. variants instea= d. > = > Thanks for your review. > = > The skb_zcopy() does indeed make repeated checks. So following your = > suggestion, > = > I have modified the code as follows: > = > -=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 net_zcopy_ge= t(skb_zcopy(skb)); > +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 net_zcopy_ge= t(skb_uarg(skb)); > = > Does it seem more reasonable? > = > And I plan to modify all three functions in patch version 2. > = That sounds good to me, thanks.