From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,T_DKIMWL_WL_MED, URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1165BECDFB0 for ; Fri, 13 Jul 2018 00:10:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B39612147E for ; Fri, 13 Jul 2018 00:10:23 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=osandov-com.20150623.gappssmtp.com header.i=@osandov-com.20150623.gappssmtp.com header.b="GdaJopza" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B39612147E Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=osandov.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387787AbeGMAVq (ORCPT ); Thu, 12 Jul 2018 20:21:46 -0400 Received: from mail-pg1-f172.google.com ([209.85.215.172]:33401 "EHLO mail-pg1-f172.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2387766AbeGMAVq (ORCPT ); Thu, 12 Jul 2018 20:21:46 -0400 Received: by mail-pg1-f172.google.com with SMTP id r5-v6so4340530pgv.0 for ; Thu, 12 Jul 2018 17:09:48 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=osandov-com.20150623.gappssmtp.com; s=20150623; h=from:to:cc:subject:date:message-id:in-reply-to:references; bh=iES641aH5TZrbGpfBkO6jWH7ydYNqg2y0U3mVozYm6Y=; b=GdaJopza3OjRRmzjTqQI4ZrB7xNUarcdhpzkBysYEYXZp9cKBapeUde9sp2qljK4GX IwKUOxhuGHm1vr3T5tIB2rl+IKreoy0c1I83MEfqjz4bTRMeOmOdNN1LVDU7x+qQNDEy eOjnc9Pmx0qHnjUS9c8n2nqBKWVWKxFWuJtx73Sw0RhKisOzsuECFv+Sk3B6rqR0o1rB qnnUDiwkHJTVyx9ROVDD9oklzT9B3Feu5mvs+64RE7V5YNi5GDAwYEnYw5OdFeUGII43 h1MEH61RZX21R+Zu6Lhy1PqTDaRlWhJev9NGThULI3DdD+LGc6uT7M13bDamj0WTpnak wLVQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references; bh=iES641aH5TZrbGpfBkO6jWH7ydYNqg2y0U3mVozYm6Y=; b=BjZeRhG/ZyLbGciTFI/T81F7r90pFFuIyTqXAnGLTO/YjilGaAwdquz8GsHR8snj75 ENd+sjGKGXSWDlNhyMeNKzsRal0CcL7SNydIbAyhzGmKYaEJSH/zOsY56G60TGe6WjjP 7EY8jHtph9KRdEjKzedMEYCJLkKaghLM0Sh/bpHjgrIXFNkXnwNsHgfiXEVmSvDI0lHi +T1VkPu+IdAJIskYYi06WdUlPjs4ftMKiu6wPo0Vn1/1KpUPP/RKmaKze47OuEZYoB2r ALhp9CFH6GoTOhlNnSf6rP/7Zkex4gTCIvV3oM0eYm35QzHRy7eyEgN067HqPT5Y4lsj 0thQ== X-Gm-Message-State: AOUpUlFm6x5ke7bwz+Q9vfEuZN99U4zDxAx92wI65eggx/5Fr+//h2/I Z/Xg0cy3eaaY8X5a5wZoclAlQpR4f6Y= X-Google-Smtp-Source: AAOMgpeM0x3lGpdT5TC3aqhDf+bl2oxb4ih/0RMn8BWCuatbcRgols+eyH96UeUCn6pe+FHCM17UlA== X-Received: by 2002:a62:cc4d:: with SMTP id a74-v6mr4602311pfg.200.1531440588000; Thu, 12 Jul 2018 17:09:48 -0700 (PDT) Received: from vader.thefacebook.com ([2620:10d:c090:200::5:74a0]) by smtp.gmail.com with ESMTPSA id b86-v6sm4452067pfj.35.2018.07.12.17.09.47 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 12 Jul 2018 17:09:47 -0700 (PDT) From: Omar Sandoval To: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, Andrew Morton Cc: Alexey Dobriyan , Eric Biederman , James Morse , Bhupesh Sharma , kernel-team@fb.com Subject: [PATCH v2 2/7] proc/kcore: replace kclist_lock rwlock with rwsem Date: Thu, 12 Jul 2018 17:09:34 -0700 Message-Id: <783ba3becc424db45e5d5c93559fc40ef6173f01.1531440458.git.osandov@fb.com> X-Mailer: git-send-email 2.18.0 In-Reply-To: References: Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Omar Sandoval Now we only need kclist_lock from user context and at fs init time, and the following changes need to sleep while holding the kclist_lock. Signed-off-by: Omar Sandoval --- fs/proc/kcore.c | 32 +++++++++++++++----------------- 1 file changed, 15 insertions(+), 17 deletions(-) diff --git a/fs/proc/kcore.c b/fs/proc/kcore.c index ddeeb3a5a015..def92fccb167 100644 --- a/fs/proc/kcore.c +++ b/fs/proc/kcore.c @@ -59,8 +59,8 @@ struct memelfnote }; static LIST_HEAD(kclist_head); -static DEFINE_RWLOCK(kclist_lock); -static int kcore_need_update = 1; +static DECLARE_RWSEM(kclist_lock); +static atomic_t kcore_need_update = ATOMIC_INIT(1); /* This doesn't grab kclist_lock, so it should only be used at init time. */ void @@ -117,8 +117,8 @@ static void __kcore_update_ram(struct list_head *list) struct kcore_list *tmp, *pos; LIST_HEAD(garbage); - write_lock(&kclist_lock); - if (kcore_need_update) { + down_write(&kclist_lock); + if (atomic_cmpxchg(&kcore_need_update, 1, 0)) { list_for_each_entry_safe(pos, tmp, &kclist_head, list) { if (pos->type == KCORE_RAM || pos->type == KCORE_VMEMMAP) @@ -127,9 +127,8 @@ static void __kcore_update_ram(struct list_head *list) list_splice_tail(list, &kclist_head); } else list_splice(list, &garbage); - kcore_need_update = 0; proc_root_kcore->size = get_kcore_size(&nphdr, &size); - write_unlock(&kclist_lock); + up_write(&kclist_lock); free_kclist_ents(&garbage); } @@ -452,11 +451,11 @@ read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos) int nphdr; unsigned long start; - read_lock(&kclist_lock); + down_read(&kclist_lock); size = get_kcore_size(&nphdr, &elf_buflen); if (buflen == 0 || *fpos >= size) { - read_unlock(&kclist_lock); + up_read(&kclist_lock); return 0; } @@ -473,11 +472,11 @@ read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos) tsz = buflen; elf_buf = kzalloc(elf_buflen, GFP_ATOMIC); if (!elf_buf) { - read_unlock(&kclist_lock); + up_read(&kclist_lock); return -ENOMEM; } elf_kcore_store_hdr(elf_buf, nphdr, elf_buflen); - read_unlock(&kclist_lock); + up_read(&kclist_lock); if (copy_to_user(buffer, elf_buf + *fpos, tsz)) { kfree(elf_buf); return -EFAULT; @@ -492,7 +491,7 @@ read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos) if (buflen == 0) return acc; } else - read_unlock(&kclist_lock); + up_read(&kclist_lock); /* * Check to see if our file offset matches with any of @@ -505,12 +504,12 @@ read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos) while (buflen) { struct kcore_list *m; - read_lock(&kclist_lock); + down_read(&kclist_lock); list_for_each_entry(m, &kclist_head, list) { if (start >= m->addr && start < (m->addr+m->size)) break; } - read_unlock(&kclist_lock); + up_read(&kclist_lock); if (&m->list == &kclist_head) { if (clear_user(buffer, tsz)) @@ -563,7 +562,7 @@ static int open_kcore(struct inode *inode, struct file *filp) if (!filp->private_data) return -ENOMEM; - if (kcore_need_update) + if (atomic_read(&kcore_need_update)) kcore_update_ram(); if (i_size_read(inode) != proc_root_kcore->size) { inode_lock(inode); @@ -593,9 +592,8 @@ static int __meminit kcore_callback(struct notifier_block *self, switch (action) { case MEM_ONLINE: case MEM_OFFLINE: - write_lock(&kclist_lock); - kcore_need_update = 1; - write_unlock(&kclist_lock); + atomic_set(&kcore_need_update, 1); + break; } return NOTIFY_OK; } -- 2.18.0