Date: Thu, 21 May 2015 09:21:06 +0000 (UTC) From: Andrew Rybchenko <arybchik@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-10@freebsd.org Subject: svn commit: r283214 - stable/10/sys/dev/sfxge Message-ID: <201505210921.t4L9L6P8075591@svn.freebsd.org>
next in thread | raw e-mail | index | archive | help
Author: arybchik Date: Thu May 21 09:21:05 2015 New Revision: 283214 URL: https://svnweb.freebsd.org/changeset/base/283214 Log: MFC: r283048 sfxge: fix overflow queue freeze If TxQ lock is obtained, deferred packet list shold be serviced even if the packet addition fails because of overflow. Without the patch freeze happens if: - queue is not blocked (i.e. completion does not trigger unblock and service) - put-list overflow (1024 entries) - sfxge_tx_packet_add() acquires TxQ lock just as it is released it in sfxge_tx_qdpl_service() on the second CPU but before pending check - sfxge_tx_packet_add() swizzles put-list to get-list, fails because of non-tcp get-list overflow and returns without packet list service - sfxge_tx_qdpl_service() on the second CPU checks that there are no pending packets in the put-list and returns Other possible solution is to guaranee that maximum length of the put-list is less than maximum length of any get-list. Sponsored by: Solarflare Communications, Inc. Modified: stable/10/sys/dev/sfxge/sfxge_tx.c Directory Properties: stable/10/ (props changed) Modified: stable/10/sys/dev/sfxge/sfxge_tx.c ============================================================================== --- stable/10/sys/dev/sfxge/sfxge_tx.c Thu May 21 09:15:19 2015 (r283213) +++ stable/10/sys/dev/sfxge/sfxge_tx.c Thu May 21 09:21:05 2015 (r283214) @@ -619,18 +619,12 @@ sfxge_tx_packet_add(struct sfxge_txq *tx sfxge_tx_qdpl_swizzle(txq); rc = sfxge_tx_qdpl_put_locked(txq, m); - if (rc != 0) { - SFXGE_TXQ_UNLOCK(txq); - return (rc); - } /* Try to service the list. */ sfxge_tx_qdpl_service(txq); /* Lock has been dropped. */ } else { rc = sfxge_tx_qdpl_put_unlocked(txq, m); - if (rc != 0) - return (rc); /* * Try to grab the lock again. @@ -639,7 +633,7 @@ sfxge_tx_packet_add(struct sfxge_txq *tx * the deferred packet list. If we are not able to get * the lock, another thread is processing the list. */ - if (SFXGE_TXQ_TRYLOCK(txq)) { + if ((rc == 0) && SFXGE_TXQ_TRYLOCK(txq)) { sfxge_tx_qdpl_service(txq); /* Lock has been dropped. */ } @@ -647,7 +641,7 @@ sfxge_tx_packet_add(struct sfxge_txq *tx SFXGE_TXQ_LOCK_ASSERT_NOTOWNED(txq); - return (0); + return (rc); } static void
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?201505210921.t4L9L6P8075591>