From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751612Ab1L3Qmn (ORCPT ); Fri, 30 Dec 2011 11:42:43 -0500 Received: from e4.ny.us.ibm.com ([32.97.182.144]:59204 "EHLO e4.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750871Ab1L3Qmm (ORCPT ); Fri, 30 Dec 2011 11:42:42 -0500 From: Seth Jennings To: Greg Kroah-Hartman Cc: Seth Jennings , Dan Magenheimer , Brian King , devel@driverdev.osuosl.org, linux-kernel@vger.kernel.org Subject: [PATCH] staging: zcache: fix serialization bug in zv stats Date: Fri, 30 Dec 2011 10:42:15 -0600 Message-Id: <1325263335-16254-1-git-send-email-sjenning@linux.vnet.ibm.com> X-Mailer: git-send-email 1.7.5.4 x-cbid: 11123016-3534-0000-0000-000004138A39 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org In a multithreaded workload, the zv_curr_dist_counts and zv_cumul_dist_counts statistics are being corrupted because the increments and decrements in zv_create and zv_free are not atomic. This patch converts these statistics and their corresponding increments/decrements/reads to atomic operations. Based on v3.2-rc7 Signed-off-by: Seth Jennings --- drivers/staging/zcache/zcache-main.c | 14 +++++++------- 1 files changed, 7 insertions(+), 7 deletions(-) diff --git a/drivers/staging/zcache/zcache-main.c b/drivers/staging/zcache/zcache-main.c index 56c1f9c..d39bb51 100644 --- a/drivers/staging/zcache/zcache-main.c +++ b/drivers/staging/zcache/zcache-main.c @@ -655,8 +655,8 @@ static unsigned int zv_max_zsize = (PAGE_SIZE / 8) * 7; */ static unsigned int zv_max_mean_zsize = (PAGE_SIZE / 8) * 5; -static unsigned long zv_curr_dist_counts[NCHUNKS]; -static unsigned long zv_cumul_dist_counts[NCHUNKS]; +static atomic_t zv_curr_dist_counts[NCHUNKS]; +static atomic_t zv_cumul_dist_counts[NCHUNKS]; static struct zv_hdr *zv_create(struct xv_pool *xvpool, uint32_t pool_id, struct tmem_oid *oid, uint32_t index, @@ -675,8 +675,8 @@ static struct zv_hdr *zv_create(struct xv_pool *xvpool, uint32_t pool_id, &page, &offset, ZCACHE_GFP_MASK); if (unlikely(ret)) goto out; - zv_curr_dist_counts[chunks]++; - zv_cumul_dist_counts[chunks]++; + atomic_inc(&zv_curr_dist_counts[chunks]); + atomic_inc(&zv_cumul_dist_counts[chunks]); zv = kmap_atomic(page, KM_USER0) + offset; zv->index = index; zv->oid = *oid; @@ -698,7 +698,7 @@ static void zv_free(struct xv_pool *xvpool, struct zv_hdr *zv) ASSERT_SENTINEL(zv, ZVH); BUG_ON(chunks >= NCHUNKS); - zv_curr_dist_counts[chunks]--; + atomic_dec(&zv_curr_dist_counts[chunks]); size -= sizeof(*zv); BUG_ON(size == 0); INVERT_SENTINEL(zv, ZVH); @@ -738,7 +738,7 @@ static int zv_curr_dist_counts_show(char *buf) char *p = buf; for (i = 0; i < NCHUNKS; i++) { - n = zv_curr_dist_counts[i]; + n = atomic_read(&zv_curr_dist_counts[i]); p += sprintf(p, "%lu ", n); chunks += n; sum_total_chunks += i * n; @@ -754,7 +754,7 @@ static int zv_cumul_dist_counts_show(char *buf) char *p = buf; for (i = 0; i < NCHUNKS; i++) { - n = zv_cumul_dist_counts[i]; + n = atomic_read(&zv_cumul_dist_counts[i]); p += sprintf(p, "%lu ", n); chunks += n; sum_total_chunks += i * n; -- 1.7.5.4