From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from userp2130.oracle.com ([156.151.31.86]) by bombadil.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1jWUfF-0003bC-4T for kexec@lists.infradead.org; Thu, 07 May 2020 00:45:29 +0000 From: Anthony Yznaga Subject: [RFC 33/43] PKRAM: atomically add and remove link pages Date: Wed, 6 May 2020 17:41:59 -0700 Message-Id: <1588812129-8596-34-git-send-email-anthony.yznaga@oracle.com> In-Reply-To: <1588812129-8596-1-git-send-email-anthony.yznaga@oracle.com> References: <1588812129-8596-1-git-send-email-anthony.yznaga@oracle.com> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "kexec" Errors-To: kexec-bounces+dwmw2=infradead.org@lists.infradead.org To: linux-mm@kvack.org, linux-kernel@vger.kernel.org Cc: x86@kernel.org, linux-doc@vger.kernel.org, gustavo@embeddedor.com, peterz@infradead.org, kexec@lists.infradead.org, paul.c.lai@intel.com, dave.hansen@linux.intel.com, mhocko@kernel.org, lei.l.li@intel.com, nivedita@alum.mit.edu, ziqian.lzq@antfin.com, hpa@zytor.com, ardb@kernel.org, ashok.raj@intel.com, bhe@redhat.com, corbet@lwn.net, masahiroy@kernel.org, rafael.j.wysocki@intel.com, hughd@google.com, willy@infradead.org, rppt@linux.ibm.com, mingo@redhat.com, vdavydov.dev@gmail.com, ying.huang@intel.com, Thomas.Lendacky@amd.com, kevin.tian@intel.com, jroedel@suse.de, keescook@chromium.org, dan.j.williams@intel.com, bp@alien8.de, zhiyuan.lv@intel.com, luto@kernel.org, tglx@linutronix.de, andriy.shevchenko@linux.intel.com, dima@golovin.in, yang.shi@linux.alibaba.com, ndesaulniers@google.com, zhenzhong.duan@oracle.com, guro@fb.com, minchan@kernel.org, ebiederm@xmission.com, jason.zeng@intel.com, hannes@cmpxchg.org, linux-fsdevel@vger.kernel.org, akpm@linux-foundation.org, daniel.kiper@oracle.com Add and remove pkram_link pages from a pkram_obj atomically to prepare for multithreading. Signed-off-by: Anthony Yznaga --- mm/pkram.c | 27 ++++++++++++++++++--------- 1 file changed, 18 insertions(+), 9 deletions(-) diff --git a/mm/pkram.c b/mm/pkram.c index 5f4e4d12865f..042c14dedc25 100644 --- a/mm/pkram.c +++ b/mm/pkram.c @@ -551,22 +551,31 @@ static void pkram_truncate(void) static void pkram_add_link(struct pkram_link *link, struct pkram_obj *obj) { - link->link_pfn = obj->link_pfn; - obj->link_pfn = page_to_pfn(virt_to_page(link)); + __u64 link_pfn = page_to_pfn(virt_to_page(link)); + __u64 *head = &obj->link_pfn; + + do { + link->link_pfn = *head; + } while (cmpxchg64(head, link->link_pfn, link_pfn) != link->link_pfn); } static struct pkram_link *pkram_remove_link(struct pkram_obj *obj) { struct pkram_link *current_link; + __u64 *head = &obj->link_pfn; + __u64 head_pfn = *head; + + while (head_pfn) { + current_link = pfn_to_kaddr(head_pfn); + if (cmpxchg64(head, head_pfn, current_link->link_pfn) == head_pfn) { + current_link->link_pfn = 0; + return current_link; + } - if (!obj->link_pfn) - return NULL; - - current_link = pfn_to_kaddr(obj->link_pfn); - obj->link_pfn = current_link->link_pfn; - current_link->link_pfn = 0; + head_pfn = *head; + } - return current_link; + return NULL; } static void pkram_stream_init(struct pkram_stream *ps, -- 2.13.3 _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec