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Mon, 02 Oct 2023 05:16:52 -0700 (PDT) Received: from localhost ([81.168.73.77]) by smtp.gmail.com with ESMTPSA id d4-20020a05600c34c400b003feea62440bsm7232984wmq.43.2023.10.02.05.16.51 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 02 Oct 2023 05:16:51 -0700 (PDT) Date: Mon, 2 Oct 2023 13:16:50 +0100 From: Martin Habets To: edward.cree@amd.com Cc: linux-net-drivers@amd.com, davem@davemloft.net, kuba@kernel.org, edumazet@google.com, pabeni@redhat.com, Edward Cree , netdev@vger.kernel.org, sudheer.mogilappagari@intel.com, jdamato@fastly.com, andrew@lunn.ch, mw@semihalf.com, linux@armlinux.org.uk, sgoutham@marvell.com, gakula@marvell.com, sbhatta@marvell.com, hkelam@marvell.com, saeedm@nvidia.com, leon@kernel.org Subject: Re: [PATCH v4 net-next 6/7] net: ethtool: add a mutex protecting RSS contexts Message-ID: <20231002121650.GF21694@gmail.com> Mail-Followup-To: edward.cree@amd.com, linux-net-drivers@amd.com, davem@davemloft.net, kuba@kernel.org, edumazet@google.com, pabeni@redhat.com, Edward Cree , netdev@vger.kernel.org, sudheer.mogilappagari@intel.com, jdamato@fastly.com, andrew@lunn.ch, mw@semihalf.com, linux@armlinux.org.uk, sgoutham@marvell.com, gakula@marvell.com, sbhatta@marvell.com, hkelam@marvell.com, saeedm@nvidia.com, leon@kernel.org References: Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Spam-Status: No, score=-2.1 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,FREEMAIL_FROM, RCVD_IN_DNSWL_BLOCKED,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net On Wed, Sep 27, 2023 at 07:13:37PM +0100, edward.cree@amd.com wrote: > From: Edward Cree > > While this is not needed to serialise the ethtool entry points (which > are all under RTNL), drivers may have cause to asynchronously access > dev->ethtool->rss_ctx; taking dev->ethtool->rss_lock allows them to > do this safely without needing to take the RTNL. > > Signed-off-by: Edward Cree Reviewed-by: Martin Habets > --- > include/linux/ethtool.h | 3 +++ > net/core/dev.c | 5 +++++ > net/ethtool/ioctl.c | 7 +++++++ > 3 files changed, 15 insertions(+) > > diff --git a/include/linux/ethtool.h b/include/linux/ethtool.h > index c8963bde9289..d15a21bd6f12 100644 > --- a/include/linux/ethtool.h > +++ b/include/linux/ethtool.h > @@ -1026,11 +1026,14 @@ int ethtool_virtdev_set_link_ksettings(struct net_device *dev, > /** > * struct ethtool_netdev_state - per-netdevice state for ethtool features > * @rss_ctx: XArray of custom RSS contexts > + * @rss_lock: Protects entries in @rss_ctx. May be taken from > + * within RTNL. > * @rss_ctx_max_id: maximum (exclusive) supported RSS context ID > * @wol_enabled: Wake-on-LAN is enabled > */ > struct ethtool_netdev_state { > struct xarray rss_ctx; > + struct mutex rss_lock; > u32 rss_ctx_max_id; > u32 wol_enabled:1; > }; > diff --git a/net/core/dev.c b/net/core/dev.c > index 69579d9cd7ba..c57456ed4be8 100644 > --- a/net/core/dev.c > +++ b/net/core/dev.c > @@ -10074,6 +10074,7 @@ int register_netdevice(struct net_device *dev) > > /* rss ctx ID 0 is reserved for the default context, start from 1 */ > xa_init_flags(&dev->ethtool->rss_ctx, XA_FLAGS_ALLOC1); > + mutex_init(&dev->ethtool->rss_lock); > > spin_lock_init(&dev->addr_list_lock); > netdev_set_addr_lockdep_class(dev); > @@ -10882,6 +10883,7 @@ static void netdev_rss_contexts_free(struct net_device *dev) > struct ethtool_rxfh_context *ctx; > unsigned long context; > > + mutex_lock(&dev->ethtool->rss_lock); > if (dev->ethtool_ops->create_rxfh_context || > dev->ethtool_ops->set_rxfh_context) > xa_for_each(&dev->ethtool->rss_ctx, context, ctx) { > @@ -10903,6 +10905,7 @@ static void netdev_rss_contexts_free(struct net_device *dev) > kfree(ctx); > } > xa_destroy(&dev->ethtool->rss_ctx); > + mutex_unlock(&dev->ethtool->rss_lock); > } > > /** > @@ -11016,6 +11019,8 @@ void unregister_netdevice_many_notify(struct list_head *head, > if (dev->netdev_ops->ndo_uninit) > dev->netdev_ops->ndo_uninit(dev); > > + mutex_destroy(&dev->ethtool->rss_lock); > + > if (skb) > rtmsg_ifinfo_send(skb, dev, GFP_KERNEL, portid, nlh); > > diff --git a/net/ethtool/ioctl.c b/net/ethtool/ioctl.c > index 3920ddee3ee2..d21bbc92e6fc 100644 > --- a/net/ethtool/ioctl.c > +++ b/net/ethtool/ioctl.c > @@ -1258,6 +1258,7 @@ static noinline_for_stack int ethtool_set_rxfh(struct net_device *dev, > u8 *rss_config; > u32 rss_cfg_offset = offsetof(struct ethtool_rxfh, rss_config[0]); > bool create = false, delete = false; > + bool locked = false; /* dev->ethtool->rss_lock taken */ > > if (!ops->get_rxnfc || !ops->set_rxfh) > return -EOPNOTSUPP; > @@ -1335,6 +1336,10 @@ static noinline_for_stack int ethtool_set_rxfh(struct net_device *dev, > } > } > > + if (rxfh.rss_context) { > + mutex_lock(&dev->ethtool->rss_lock); > + locked = true; > + } > if (create) { > if (delete) { > ret = -EINVAL; > @@ -1455,6 +1460,8 @@ static noinline_for_stack int ethtool_set_rxfh(struct net_device *dev, > } > > out: > + if (locked) > + mutex_unlock(&dev->ethtool->rss_lock); > kfree(rss_config); > return ret; > }