From patchwork Fri May 10 00:00:30 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Chenbo Feng X-Patchwork-Id: 10937983 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 693FF1398 for ; Fri, 10 May 2019 00:00:56 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 5A6DB28B37 for ; Fri, 10 May 2019 00:00:56 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 4B2E228BF3; Fri, 10 May 2019 00:00:56 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-15.5 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI, USER_IN_DEF_DKIM_WL autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id B205228B37 for ; Fri, 10 May 2019 00:00:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726862AbfEJAAi (ORCPT ); Thu, 9 May 2019 20:00:38 -0400 Received: from mail-qt1-f202.google.com ([209.85.160.202]:53006 "EHLO mail-qt1-f202.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726694AbfEJAAi (ORCPT ); Thu, 9 May 2019 20:00:38 -0400 Received: by mail-qt1-f202.google.com with SMTP id c48so3261253qta.19 for ; Thu, 09 May 2019 17:00:38 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:in-reply-to:message-id:mime-version:references:subject:from:to :cc; bh=gajNK+eaXAkA4VRl6/dTyngKGgS840DD0yMbWQwHpJk=; b=StQx3pXTz9nlOqpe4jzFUgYd8pSqETXTQnTWa9CFOUrMtJPFB16HL/knloQh0RvsDL YEG1/aMcAQdEJ7eeT6+Ec/x4kt0MgcKkTAzForocIa0xsDIqFTNOoVPzcpfDHsf5e7CW AORrgXG9ozxsU8TDoeFyf1PjTy+3Jx6JhJnOYJ3kKQv13cMuZl/NXFztkd/JzpEMYtQK UHHxe38yoAmLaTa7Ep7j92pCbpXvYH2McHunc0CA83y7iFE81kDp1aHFg1Msi/WGhyZP OMNagW/InIDVAHIc5PHIhPfNJw02NNDYMg3eqBvFy/ic3uHIdkW/XDwE4MKYAXF44AaE E3zg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=gajNK+eaXAkA4VRl6/dTyngKGgS840DD0yMbWQwHpJk=; b=CZOLtp0dhQ7l9zP0MRxaReHwJTT3xeKNXLhhnSsF+seF2zshWRtqgRK3r11ocp5NoY 9oucBUyByVtMi410XoIZbq0MHeiQAPkWMris8HFFIWV0+OWEYTn2rRcGPk9uay/sozaE zhvH/8OPTY4zN+vZbRHraQCazJbHuRXTntbawCpxrX2VKBKQ2n9PrsR8ACrypEnvP8or pF8vKDaUQhv2/L7y51gPoK69IbMCr51HaaVJ1FgZh+nh8PbtCdpkShIGzR6cHW2oCReu kPehB82fEHXaXGtFsRMnvNAQ54mTFGWn3mXeSGN7bjqMKyQlbGQq+WJluWhmVER2JX6E bzNg== X-Gm-Message-State: APjAAAXfuyyLPfixyzsnJaFkFzH3izFOUIXSe/Fl9hZiey+8Xb7VIxvP TQDFniw+yXXDFbWdHZdmxxPpVPTcPA== X-Google-Smtp-Source: APXvYqyrykg6LhonB5E0Xc2fQnfppFoKDq3KTv5cA/JDKFevQ+EjrXDwR8LM84x3PrH7bXcbkJ2Fbz+60g== X-Received: by 2002:ac8:375d:: with SMTP id p29mr6286750qtb.88.1557446437681; Thu, 09 May 2019 17:00:37 -0700 (PDT) Date: Thu, 9 May 2019 17:00:30 -0700 In-Reply-To: <20190510000032.40749-1-fengc@google.com> Message-Id: <20190510000032.40749-2-fengc@google.com> Mime-Version: 1.0 References: <20190510000032.40749-1-fengc@google.com> X-Mailer: git-send-email 2.21.0.1020.gf2820cf01a-goog Subject: [dma-buf v3 1/3] dma-buf: give each buffer a full-fledged inode From: Chenbo Feng To: linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, linux-media@vger.kernel.org Cc: Sumit Semwal , Daniel Vetter , erickreyes@google.com, kernel-team@android.com Sender: linux-media-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-media@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP From: Greg Hackmann By traversing /proc/*/fd and /proc/*/map_files, processes with CAP_ADMIN can get a lot of fine-grained data about how shmem buffers are shared among processes. stat(2) on each entry gives the caller a unique ID (st_ino), the buffer's size (st_size), and even the number of pages currently charged to the buffer (st_blocks / 512). In contrast, all dma-bufs share the same anonymous inode. So while we can count how many dma-buf fds or mappings a process has, we can't get the size of the backing buffers or tell if two entries point to the same dma-buf. On systems with debugfs, we can get a per-buffer breakdown of size and reference count, but can't tell which processes are actually holding the references to each buffer. Replace the singleton inode with full-fledged inodes allocated by alloc_anon_inode(). This involves creating and mounting a mini-pseudo-filesystem for dma-buf, following the example in fs/aio.c. Signed-off-by: Greg Hackmann Signed-off-by: Chenbo Feng --- drivers/dma-buf/dma-buf.c | 63 ++++++++++++++++++++++++++++++++++---- include/uapi/linux/magic.h | 1 + 2 files changed, 58 insertions(+), 6 deletions(-) diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c index 7c858020d14b..ffd5a2ad7d6f 100644 --- a/drivers/dma-buf/dma-buf.c +++ b/drivers/dma-buf/dma-buf.c @@ -34,8 +34,10 @@ #include #include #include +#include #include +#include static inline int is_dma_buf_file(struct file *); @@ -46,6 +48,25 @@ struct dma_buf_list { static struct dma_buf_list db_list; +static const struct dentry_operations dma_buf_dentry_ops = { + .d_dname = simple_dname, +}; + +static struct vfsmount *dma_buf_mnt; + +static struct dentry *dma_buf_fs_mount(struct file_system_type *fs_type, + int flags, const char *name, void *data) +{ + return mount_pseudo(fs_type, "dmabuf:", NULL, &dma_buf_dentry_ops, + DMA_BUF_MAGIC); +} + +static struct file_system_type dma_buf_fs_type = { + .name = "dmabuf", + .mount = dma_buf_fs_mount, + .kill_sb = kill_anon_super, +}; + static int dma_buf_release(struct inode *inode, struct file *file) { struct dma_buf *dmabuf; @@ -338,6 +359,31 @@ static inline int is_dma_buf_file(struct file *file) return file->f_op == &dma_buf_fops; } +static struct file *dma_buf_getfile(struct dma_buf *dmabuf, int flags) +{ + struct file *file; + struct inode *inode = alloc_anon_inode(dma_buf_mnt->mnt_sb); + + if (IS_ERR(inode)) + return ERR_CAST(inode); + + inode->i_size = dmabuf->size; + inode_set_bytes(inode, dmabuf->size); + + file = alloc_file_pseudo(inode, dma_buf_mnt, "dmabuf", + flags, &dma_buf_fops); + if (IS_ERR(file)) + goto err_alloc_file; + file->f_flags = flags & (O_ACCMODE | O_NONBLOCK); + file->private_data = dmabuf; + + return file; + +err_alloc_file: + iput(inode); + return file; +} + /** * DOC: dma buf device access * @@ -433,8 +479,7 @@ struct dma_buf *dma_buf_export(const struct dma_buf_export_info *exp_info) } dmabuf->resv = resv; - file = anon_inode_getfile("dmabuf", &dma_buf_fops, dmabuf, - exp_info->flags); + file = dma_buf_getfile(dmabuf, exp_info->flags); if (IS_ERR(file)) { ret = PTR_ERR(file); goto err_dmabuf; @@ -1025,8 +1070,8 @@ static int dma_buf_debug_show(struct seq_file *s, void *unused) return ret; seq_puts(s, "\nDma-buf Objects:\n"); - seq_printf(s, "%-8s\t%-8s\t%-8s\t%-8s\texp_name\n", - "size", "flags", "mode", "count"); + seq_printf(s, "%-8s\t%-8s\t%-8s\t%-8s\texp_name\t%-8s\n", + "size", "flags", "mode", "count", "ino"); list_for_each_entry(buf_obj, &db_list.head, list_node) { ret = mutex_lock_interruptible(&buf_obj->lock); @@ -1037,11 +1082,12 @@ static int dma_buf_debug_show(struct seq_file *s, void *unused) continue; } - seq_printf(s, "%08zu\t%08x\t%08x\t%08ld\t%s\n", + seq_printf(s, "%08zu\t%08x\t%08x\t%08ld\t%s\t%08lu\n", buf_obj->size, buf_obj->file->f_flags, buf_obj->file->f_mode, file_count(buf_obj->file), - buf_obj->exp_name); + buf_obj->exp_name, + file_inode(buf_obj->file)->i_ino); robj = buf_obj->resv; while (true) { @@ -1136,6 +1182,10 @@ static inline void dma_buf_uninit_debugfs(void) static int __init dma_buf_init(void) { + dma_buf_mnt = kern_mount(&dma_buf_fs_type); + if (IS_ERR(dma_buf_mnt)) + return PTR_ERR(dma_buf_mnt); + mutex_init(&db_list.lock); INIT_LIST_HEAD(&db_list.head); dma_buf_init_debugfs(); @@ -1146,5 +1196,6 @@ subsys_initcall(dma_buf_init); static void __exit dma_buf_deinit(void) { dma_buf_uninit_debugfs(); + kern_unmount(dma_buf_mnt); } __exitcall(dma_buf_deinit); diff --git a/include/uapi/linux/magic.h b/include/uapi/linux/magic.h index f8c00045d537..665e18627f78 100644 --- a/include/uapi/linux/magic.h +++ b/include/uapi/linux/magic.h @@ -91,5 +91,6 @@ #define UDF_SUPER_MAGIC 0x15013346 #define BALLOON_KVM_MAGIC 0x13661366 #define ZSMALLOC_MAGIC 0x58295829 +#define DMA_BUF_MAGIC 0x444d4142 /* "DMAB" */ #endif /* __LINUX_MAGIC_H__ */