Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756299AbbGFNvY (ORCPT ); Mon, 6 Jul 2015 09:51:24 -0400 Received: from orbit.nwl.cc ([176.31.251.142]:58681 "EHLO mail.nwl.cc" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751651AbbGFNvW (ORCPT ); Mon, 6 Jul 2015 09:51:22 -0400 From: Phil Sutter To: Thomas Graf Cc: sparclinux@vger.kernel.org, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, davem@davemloft.net, herbert@gondor.apana.org.au, daniel@iogearbox.net, geert@linux-m68k.org, mroos@linux.ee Subject: [PATCH v2] rhashtable: fix for resize events during table walk Date: Mon, 6 Jul 2015 15:51:20 +0200 Message-Id: <1436190680-21887-1-git-send-email-phil@nwl.cc> X-Mailer: git-send-email 2.1.2 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1522 Lines: 51 If rhashtable_walk_next detects a resize operation in progress, it jumps to the new table and continues walking that one. But it misses to drop the reference to it's current item, leading it to continue traversing the new table's bucket in which the current item is sorted into, and after reaching that bucket's end continues traversing the new table's second bucket instead of the first one, thereby potentially missing items. This fixes the rhashtable runtime test for me. Bug probably introduced by Herbert Xu's patch eddee5ba ("rhashtable: Fix walker behaviour during rehash") although not explicitly tested. Fixes: eddee5ba ("rhashtable: Fix walker behaviour during rehash") Signed-off-by: Phil Sutter --- Changes since v1: - Use simplified solution suggested by Herbert Xu. --- lib/rhashtable.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/lib/rhashtable.c b/lib/rhashtable.c index a60a6d3..cc0c697 100644 --- a/lib/rhashtable.c +++ b/lib/rhashtable.c @@ -610,6 +610,8 @@ next: iter->skip = 0; } + iter->p = NULL; + /* Ensure we see any new tables. */ smp_rmb(); @@ -620,8 +622,6 @@ next: return ERR_PTR(-EAGAIN); } - iter->p = NULL; - return NULL; } EXPORT_SYMBOL_GPL(rhashtable_walk_next); -- 2.1.2 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/