From owner-svn-src-all@freebsd.org Sat Dec 22 15:15:46 2018 Return-Path: Delivered-To: svn-src-all@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 9D7B413562D7; Sat, 22 Dec 2018 15:15:46 +0000 (UTC) (envelope-from vmaffione@FreeBSD.org) Received: from mxrelay.nyi.freebsd.org (mxrelay.nyi.freebsd.org [IPv6:2610:1c1:1:606c::19:3]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) server-signature RSA-PSS (4096 bits) client-signature RSA-PSS (4096 bits) client-digest SHA256) (Client CN "mxrelay.nyi.freebsd.org", Issuer "Let's Encrypt Authority X3" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 4417E8B49D; Sat, 22 Dec 2018 15:15:46 +0000 (UTC) (envelope-from vmaffione@FreeBSD.org) Received: from repo.freebsd.org (repo.freebsd.org [IPv6:2610:1c1:1:6068::e6a:0]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mxrelay.nyi.freebsd.org (Postfix) with ESMTPS id 3877B26C45; Sat, 22 Dec 2018 15:15:46 +0000 (UTC) (envelope-from vmaffione@FreeBSD.org) Received: from repo.freebsd.org ([127.0.1.37]) by repo.freebsd.org (8.15.2/8.15.2) with ESMTP id wBMFFktU006899; Sat, 22 Dec 2018 15:15:46 GMT (envelope-from vmaffione@FreeBSD.org) Received: (from vmaffione@localhost) by repo.freebsd.org (8.15.2/8.15.2/Submit) id wBMFFknS006898; Sat, 22 Dec 2018 15:15:46 GMT (envelope-from vmaffione@FreeBSD.org) Message-Id: <201812221515.wBMFFknS006898@repo.freebsd.org> X-Authentication-Warning: repo.freebsd.org: vmaffione set sender to vmaffione@FreeBSD.org using -f From: Vincenzo Maffione Date: Sat, 22 Dec 2018 15:15:46 +0000 (UTC) To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r342368 - head/sys/dev/netmap X-SVN-Group: head X-SVN-Commit-Author: vmaffione X-SVN-Commit-Paths: head/sys/dev/netmap X-SVN-Commit-Revision: 342368 X-SVN-Commit-Repository: base MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Rspamd-Queue-Id: 4417E8B49D X-Spamd-Bar: -- Authentication-Results: mx1.freebsd.org X-Spamd-Result: default: False [-2.94 / 15.00]; local_wl_from(0.00)[FreeBSD.org]; NEURAL_HAM_MEDIUM(-1.00)[-0.999,0]; NEURAL_HAM_LONG(-1.00)[-0.999,0]; NEURAL_HAM_SHORT(-0.94)[-0.942,0]; ASN(0.00)[asn:11403, ipnet:2610:1c1:1::/48, country:US] X-BeenThere: svn-src-all@freebsd.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: "SVN commit messages for the entire src tree \(except for " user" and " projects" \)" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 22 Dec 2018 15:15:46 -0000 Author: vmaffione Date: Sat Dec 22 15:15:45 2018 New Revision: 342368 URL: https://svnweb.freebsd.org/changeset/base/342368 Log: netmap: fix bug in netmap_poll() optimization The bug was introduced by r339639, although it is present in the upstream netmap code since 2015. It is due to resetting the want_rx variable to POLLIN, rather than resetting it to POLLIN|POLLRDNORM. It only affects select(), which uses POLLRDNORM. poll() is not affected, because it uses POLLIN. Also, it only affects FreeBSD, because Linux skips the optimization implemented by the piece of code where the bug occurs. MFC after: 3 days Sponsored by: Sunny Valley Networks Modified: head/sys/dev/netmap/netmap.c Modified: head/sys/dev/netmap/netmap.c ============================================================================== --- head/sys/dev/netmap/netmap.c Sat Dec 22 11:38:54 2018 (r342367) +++ head/sys/dev/netmap/netmap.c Sat Dec 22 15:15:45 2018 (r342368) @@ -3304,16 +3304,19 @@ netmap_poll(struct netmap_priv_d *priv, int events, NM } if (want_rx) { enum txrx t = NR_RX; - want_rx = 0; /* look for a reason to run the handlers */ + int rxsync_needed = 0; + + /* look for a reason to run the handlers */ for (i = priv->np_qfirst[t]; i < priv->np_qlast[t]; i++) { kring = NMR(na, t)[i]; if (kring->ring->cur == kring->ring->tail /* try fetch new buffers */ || kring->rhead != kring->ring->head /* release buffers */) { - want_rx = 1; + rxsync_needed = 1; + break; } } - if (!want_rx) - revents |= events & (POLLIN | POLLRDNORM); /* we have data */ + if (!rxsync_needed) + revents |= want_rx; /* we have data */ } #endif