Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934297AbbGVN3d (ORCPT ); Wed, 22 Jul 2015 09:29:33 -0400 Received: from mga11.intel.com ([192.55.52.93]:39416 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932702AbbGVN3b (ORCPT ); Wed, 22 Jul 2015 09:29:31 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.15,523,1432623600"; d="scan'208";a="528288281" Message-ID: <55AF9A2C.6000703@intel.com> Date: Wed, 22 Jul 2015 21:27:08 +0800 From: Pan Xinhui User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.5.0 MIME-Version: 1.0 To: "linux-kernel@vger.kernel.org" CC: Thomas Gleixner , mingo@redhat.com, hpa@zytor.com, x86@kernel.org, bp@suse.de, toshi.kani@hp.com, jgross@suse.com, mcgrof@suse.com, "mnipxh@163.com" , "yanmin_zhang@linux.intel.com" , Borislav Petkov Subject: [PATCH V4] x86/mm/pat: Do a small optimization and fix in reserve_memtype Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2832 Lines: 83 From: Pan Xinhui It's more reasonable to unlock memtype_lock right after rbt_memtype_check_insert. All pat_rbtree operations need to be performed while holding the memtype_lock. But codes like kfree, pr_info, etc have nothing to do with this lock. So move spin_unlock a little ahead. If *new* succeed to be stored into the rb-tree, we might hit panic. Because we access *new* in dprintk "cattr_name(new->type)". Data stored in the rb-tree might be freed at any possible time. It's obviously wrong to access such data without lock held. We use actual_type instead of new->type in dprintk. Two benefits, 1) We don't touch *new* here now so panic can be avoided. 2) As new->type is same with *new_type, We needn't to print it again, what's more, this actual_type's output can help debug. When new_type is NULL, actual_type is equal to new->type, So no key information is lost. Do a minor codes style improvement. Signed-off-by: Pan Xinhui --- change from v3: output actual_type instead of new->type. codes style improvement. update comments. change from v2: update comments. change from V1: fix an access of *new* without memtype_lock held. --- arch/x86/mm/pat.c | 14 ++++---------- 1 file changed, 4 insertions(+), 10 deletions(-) diff --git a/arch/x86/mm/pat.c b/arch/x86/mm/pat.c index 188e3e0..8fa1f07 100644 --- a/arch/x86/mm/pat.c +++ b/arch/x86/mm/pat.c @@ -521,10 +521,7 @@ int reserve_memtype(u64 start, u64 end, enum page_cache_mode req_type, is_range_ram = pat_pagerange_is_ram(start, end); if (is_range_ram == 1) { - - err = reserve_ram_pages_type(start, end, req_type, new_type); - - return err; + return reserve_ram_pages_type(start, end, req_type, new_type); } else if (is_range_ram < 0) { return -EINVAL; } @@ -538,22 +535,19 @@ int reserve_memtype(u64 start, u64 end, enum page_cache_mode req_type, new->type = actual_type; spin_lock(&memtype_lock); - err = rbt_memtype_check_insert(new, new_type); + spin_unlock(&memtype_lock); + if (err) { pr_info("x86/PAT: reserve_memtype failed [mem %#010Lx-%#010Lx], track %s, req %s\n", start, end - 1, cattr_name(new->type), cattr_name(req_type)); kfree(new); - spin_unlock(&memtype_lock); - return err; } - spin_unlock(&memtype_lock); - dprintk("reserve_memtype added [mem %#010Lx-%#010Lx], track %s, req %s, ret %s\n", - start, end - 1, cattr_name(new->type), cattr_name(req_type), + start, end - 1, cattr_name(actual_type), cattr_name(req_type), new_type ? cattr_name(*new_type) : "-"); return err; -- 1.9.1 -- 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/