Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754050AbaKKLKW (ORCPT ); Tue, 11 Nov 2014 06:10:22 -0500 Received: from youngberry.canonical.com ([91.189.89.112]:57490 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753924AbaKKLKP (ORCPT ); Tue, 11 Nov 2014 06:10:15 -0500 From: Luis Henriques To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: Eric Dumazet , "David S. Miller" , Luis Henriques Subject: [PATCH 3.16.y-ckt 078/170] tcp: md5: do not use alloc_percpu() Date: Tue, 11 Nov 2014 11:07:17 +0000 Message-Id: <1415704129-12709-79-git-send-email-luis.henriques@canonical.com> X-Mailer: git-send-email 2.1.0 In-Reply-To: <1415704129-12709-1-git-send-email-luis.henriques@canonical.com> References: <1415704129-12709-1-git-send-email-luis.henriques@canonical.com> X-Extended-Stable: 3.16 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.16.7-ckt1 -stable review patch. If anyone has any objections, please let me know. ------------------ From: Eric Dumazet commit 349ce993ac706869d553a1816426d3a4bfda02b1 upstream. percpu tcp_md5sig_pool contains memory blobs that ultimately go through sg_set_buf(). -> sg_set_page(sg, virt_to_page(buf), buflen, offset_in_page(buf)); This requires that whole area is in a physically contiguous portion of memory. And that @buf is not backed by vmalloc(). Given that alloc_percpu() can use vmalloc() areas, this does not fit the requirements. Replace alloc_percpu() by a static DEFINE_PER_CPU() as tcp_md5sig_pool is small anyway, there is no gain to dynamically allocate it. Signed-off-by: Eric Dumazet Fixes: 765cf9976e93 ("tcp: md5: remove one indirection level in tcp_md5sig_pool") Reported-by: Crestez Dan Leonard Signed-off-by: David S. Miller Signed-off-by: Luis Henriques --- net/ipv4/tcp.c | 59 ++++++++++++++++++++-------------------------------------- 1 file changed, 20 insertions(+), 39 deletions(-) diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index 0717f45b5171..59b579683c1f 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -2967,61 +2967,42 @@ EXPORT_SYMBOL(compat_tcp_getsockopt); #endif #ifdef CONFIG_TCP_MD5SIG -static struct tcp_md5sig_pool __percpu *tcp_md5sig_pool __read_mostly; +static DEFINE_PER_CPU(struct tcp_md5sig_pool, tcp_md5sig_pool); static DEFINE_MUTEX(tcp_md5sig_mutex); - -static void __tcp_free_md5sig_pool(struct tcp_md5sig_pool __percpu *pool) -{ - int cpu; - - for_each_possible_cpu(cpu) { - struct tcp_md5sig_pool *p = per_cpu_ptr(pool, cpu); - - if (p->md5_desc.tfm) - crypto_free_hash(p->md5_desc.tfm); - } - free_percpu(pool); -} +static bool tcp_md5sig_pool_populated = false; static void __tcp_alloc_md5sig_pool(void) { int cpu; - struct tcp_md5sig_pool __percpu *pool; - - pool = alloc_percpu(struct tcp_md5sig_pool); - if (!pool) - return; for_each_possible_cpu(cpu) { - struct crypto_hash *hash; - - hash = crypto_alloc_hash("md5", 0, CRYPTO_ALG_ASYNC); - if (IS_ERR_OR_NULL(hash)) - goto out_free; + if (!per_cpu(tcp_md5sig_pool, cpu).md5_desc.tfm) { + struct crypto_hash *hash; - per_cpu_ptr(pool, cpu)->md5_desc.tfm = hash; + hash = crypto_alloc_hash("md5", 0, CRYPTO_ALG_ASYNC); + if (IS_ERR_OR_NULL(hash)) + return; + per_cpu(tcp_md5sig_pool, cpu).md5_desc.tfm = hash; + } } - /* before setting tcp_md5sig_pool, we must commit all writes - * to memory. See ACCESS_ONCE() in tcp_get_md5sig_pool() + /* before setting tcp_md5sig_pool_populated, we must commit all writes + * to memory. See smp_rmb() in tcp_get_md5sig_pool() */ smp_wmb(); - tcp_md5sig_pool = pool; - return; -out_free: - __tcp_free_md5sig_pool(pool); + tcp_md5sig_pool_populated = true; } bool tcp_alloc_md5sig_pool(void) { - if (unlikely(!tcp_md5sig_pool)) { + if (unlikely(!tcp_md5sig_pool_populated)) { mutex_lock(&tcp_md5sig_mutex); - if (!tcp_md5sig_pool) + if (!tcp_md5sig_pool_populated) __tcp_alloc_md5sig_pool(); mutex_unlock(&tcp_md5sig_mutex); } - return tcp_md5sig_pool != NULL; + return tcp_md5sig_pool_populated; } EXPORT_SYMBOL(tcp_alloc_md5sig_pool); @@ -3035,13 +3016,13 @@ EXPORT_SYMBOL(tcp_alloc_md5sig_pool); */ struct tcp_md5sig_pool *tcp_get_md5sig_pool(void) { - struct tcp_md5sig_pool __percpu *p; - local_bh_disable(); - p = ACCESS_ONCE(tcp_md5sig_pool); - if (p) - return __this_cpu_ptr(p); + if (tcp_md5sig_pool_populated) { + /* coupled with smp_wmb() in __tcp_alloc_md5sig_pool() */ + smp_rmb(); + return this_cpu_ptr(&tcp_md5sig_pool); + } local_bh_enable(); return NULL; } -- 2.1.0 -- 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/