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[2a03:2880:31ff:7::face:b00c]) by smtp.gmail.com with ESMTPSA id p16-20020a1709060e9000b008779570227bsm2675642ejf.112.2023.01.25.10.52.42 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 25 Jan 2023 10:52:42 -0800 (PST) From: Breno Leitao To: kuba@kernel.org, netdev@vger.kernel.org Cc: leitao@debian.org, leit@fb.com, davem@davemloft.net, edumazet@google.com, pabeni@redhat.com, andrew@lunn.ch, linux-kernel@vger.kernel.org, Michael van der Westhuizen Subject: [PATCH v3] netpoll: Remove 4s sleep during carrier detection Date: Wed, 25 Jan 2023 10:52:30 -0800 Message-Id: <20230125185230.3574681-1-leitao@debian.org> X-Mailer: git-send-email 2.30.2 MIME-Version: 1.0 X-Spam-Status: No, score=-1.6 required=5.0 tests=BAYES_00, FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM,HEADER_FROM_DIFFERENT_DOMAINS, RCVD_IN_DNSWL_NONE,RCVD_IN_MSPIKE_H3,RCVD_IN_MSPIKE_WL,SPF_HELO_NONE, SPF_PASS autolearn=no autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: =?utf-8?q?INBOX?= X-GMAIL-THRID: =?utf-8?q?1756022110868075891?= X-GMAIL-MSGID: =?utf-8?q?1756022110868075891?= This patch removes the msleep(4s) during netpoll_setup() if the carrier appears instantly. Here are some scenarios where this workaround is counter-productive in modern ages: Servers which have BMC communicating over NC-SI via the same NIC as gets used for netconsole. BMC will keep the PHY up, hence the carrier appearing instantly. The link is fibre, SERDES getting sync could happen within 0.1Hz, and the carrier also appears instantly. Other than that, if a driver is reporting instant carrier and then losing it, this is probably a driver bug. Reported-by: Michael van der Westhuizen Signed-off-by: Breno Leitao --- v1->v2: added "RFC" in the subject v2->v3: improved the commit message --- net/core/netpoll.c | 12 +----------- 1 file changed, 1 insertion(+), 11 deletions(-) diff --git a/net/core/netpoll.c b/net/core/netpoll.c index 9be762e1d..a089b704b 100644 --- a/net/core/netpoll.c +++ b/net/core/netpoll.c @@ -682,7 +682,7 @@ int netpoll_setup(struct netpoll *np) } if (!netif_running(ndev)) { - unsigned long atmost, atleast; + unsigned long atmost; np_info(np, "device %s not up yet, forcing it\n", np->dev_name); @@ -694,7 +694,6 @@ int netpoll_setup(struct netpoll *np) } rtnl_unlock(); - atleast = jiffies + HZ/10; atmost = jiffies + carrier_timeout * HZ; while (!netif_carrier_ok(ndev)) { if (time_after(jiffies, atmost)) { @@ -704,15 +703,6 @@ int netpoll_setup(struct netpoll *np) msleep(1); } - /* If carrier appears to come up instantly, we don't - * trust it and pause so that we don't pump all our - * queued console messages into the bitbucket. - */ - - if (time_before(jiffies, atleast)) { - np_notice(np, "carrier detect appears untrustworthy, waiting 4 seconds\n"); - msleep(4000); - } rtnl_lock(); }