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AJvYcCUFZZ63NstWvJWxkNfnPu8rOCgytA3EWpnQzFJa/gtLjkObJwBsAOV915cZfP7txCVwRAs=@vger.kernel.org X-Gm-Message-State: AOJu0YwDCpSwox+EPWmIfONzQuqH2xhT5fnxXvZ7CpZ0I0KUNsBAYXWM AcRtiN/YfkcTBxxrD4VjwKGcvr2KOkR+wnluEbWu17FyvRTMV3cBCwBlANIerPSW79SVRpGsAVD 91uT9i7XcFfX1/tNozBtv+N913mwAePE= X-Gm-Gg: ASbGncvkddG9/vi7mGyq9uOiR6iALrHDde4lEZ3UnV7pJ/8y+XOaTq5Ku+saS7COKDo h62XnysENsDTLeM1rDHNgM5QwtDww/b8xiVF9bzkm4gjwOHay+7P8vB78d13Ip1gwxAr4IrygZP L9W6ZuBIzl3xpqv+5jB5+H/KUEE5STyafu0nHwbOpVVVQ3ZGd5VUrWZ/msCicol5ZB7RKAD89xK uVuHGAShi1D7tgWwmXv4JrQSfc6T4Cp6fvmQ9BoDc4pcQKgYjaiwrSuP80S X-Google-Smtp-Source: AGHT+IGbWpCA71HkuR7oTqa22GcL0bg9YQlpIglFomWMKZV3mrbvcuAL6aKEYrdGScMS93ygQSm1nWdSdxNKw6Zviyw= X-Received: by 2002:a05:6e02:97:b0:42f:6790:476c with SMTP id e9e14a558f8ab-432f905fc3dmr20080875ab.23.1761701843727; Tue, 28 Oct 2025 18:37:23 -0700 (PDT) Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 References: <20251025065310.5676-1-kerneljasonxing@gmail.com> <20251025065310.5676-2-kerneljasonxing@gmail.com> <20251028172903.677f46ba@kernel.org> In-Reply-To: <20251028172903.677f46ba@kernel.org> From: Jason Xing Date: Wed, 29 Oct 2025 09:36:47 +0800 X-Gm-Features: AWmQ_bnEufjN7yrxinjG1cqV4mzmcqDGdKn-kje9_FXsPptovuxlRGztF4a-4NA Message-ID: Subject: Re: [PATCH net-next 1/2] xsk: avoid using heavy lock when the pool is not shared To: Jakub Kicinski Cc: davem@davemloft.net, edumazet@google.com, pabeni@redhat.com, bjorn@kernel.org, magnus.karlsson@intel.com, maciej.fijalkowski@intel.com, jonathan.lemon@gmail.com, sdf@fomichev.me, ast@kernel.org, daniel@iogearbox.net, hawk@kernel.org, john.fastabend@gmail.com, horms@kernel.org, andrew+netdev@lunn.ch, bpf@vger.kernel.org, netdev@vger.kernel.org, Jason Xing Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Wed, Oct 29, 2025 at 8:29=E2=80=AFAM Jakub Kicinski wr= ote: > > On Sat, 25 Oct 2025 14:53:09 +0800 Jason Xing wrote: > > static int xsk_cq_reserve_locked(struct xsk_buff_pool *pool) > > { > > + bool lock =3D !list_is_singular(&pool->xsk_tx_list); > > unsigned long flags; > > int ret; > > > > - spin_lock_irqsave(&pool->cq_lock, flags); > > + if (lock) > > + spin_lock_irqsave(&pool->cq_lock, flags); > > ret =3D xskq_prod_reserve(pool->cq); > > - spin_unlock_irqrestore(&pool->cq_lock, flags); > > + if (lock) > > + spin_unlock_irqrestore(&pool->cq_lock, flags); > > Please explain in the commit message what guarantees that the list will > remain singular until the function exits. Thanks for bringing up a good point that I missed before. I think I might acquire xsk_tx_list_lock first to make sure xp_add_xsk() will not interfere with this process. I will figure it out soon. Thanks, Jason > -- > pw-bot: cr