Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761467AbcJ1Pw5 (ORCPT ); Fri, 28 Oct 2016 11:52:57 -0400 Received: from smtp02.citrix.com ([66.165.176.63]:62053 "EHLO SMTP02.CITRIX.COM" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1761348AbcJ1Pwt (ORCPT ); Fri, 28 Oct 2016 11:52:49 -0400 X-IronPort-AV: E=Sophos;i="5.31,410,1473120000"; d="scan'208";a="395209388" From: David Vrabel To: Alexander Viro CC: David Vrabel , , , , "Boris Ostrovsky" , Juergen Gross Subject: [PATCHv4 2/3] xenfs: replace xenbus and privcmd with symlinks Date: Fri, 28 Oct 2016 16:52:38 +0100 Message-ID: <1477669959-9486-3-git-send-email-david.vrabel@citrix.com> X-Mailer: git-send-email 2.1.4 In-Reply-To: <1477669959-9486-1-git-send-email-david.vrabel@citrix.com> References: <1477669959-9486-1-git-send-email-david.vrabel@citrix.com> MIME-Version: 1.0 Content-Type: text/plain X-DLP: MIA2 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4460 Lines: 128 /proc/xen/xenbus does not work correctly. A read blocked waiting for a xenstore message holds the mutex needed for atomic file position updates. This blocks any writes on the same file handle, which can deadlock if the write is needed to unblock the read. /proc/xen/xenbus is supposed to be identical to the character device /dev/xen/xenbus so replace the file with a symlink. Similarly, replace /proc/xen/privcmd with a symlink since it should be the same as /dev/xen/privcmd. Signed-off-by: David Vrabel --- v4: - Make xen_xenbus_fops and xen_privcmd_fops static. --- drivers/xen/privcmd.c | 5 +---- drivers/xen/privcmd.h | 3 --- drivers/xen/xenbus/xenbus_comms.h | 2 -- drivers/xen/xenbus/xenbus_dev_frontend.c | 3 +-- drivers/xen/xenfs/super.c | 10 ++++------ 5 files changed, 6 insertions(+), 17 deletions(-) delete mode 100644 drivers/xen/privcmd.h diff --git a/drivers/xen/privcmd.c b/drivers/xen/privcmd.c index 702040f..12ece8d 100644 --- a/drivers/xen/privcmd.c +++ b/drivers/xen/privcmd.c @@ -37,8 +37,6 @@ #include #include -#include "privcmd.h" - MODULE_LICENSE("GPL"); #define PRIV_VMA_LOCKED ((void *)1) @@ -644,12 +642,11 @@ static int privcmd_vma_range_is_mapped( is_mapped_fn, NULL) != 0; } -const struct file_operations xen_privcmd_fops = { +const static struct file_operations xen_privcmd_fops = { .owner = THIS_MODULE, .unlocked_ioctl = privcmd_ioctl, .mmap = privcmd_mmap, }; -EXPORT_SYMBOL_GPL(xen_privcmd_fops); static struct miscdevice privcmd_dev = { .minor = MISC_DYNAMIC_MINOR, diff --git a/drivers/xen/privcmd.h b/drivers/xen/privcmd.h deleted file mode 100644 index 14facae..0000000 --- a/drivers/xen/privcmd.h +++ /dev/null @@ -1,3 +0,0 @@ -#include - -extern const struct file_operations xen_privcmd_fops; diff --git a/drivers/xen/xenbus/xenbus_comms.h b/drivers/xen/xenbus/xenbus_comms.h index e74f9c1..39efb85 100644 --- a/drivers/xen/xenbus/xenbus_comms.h +++ b/drivers/xen/xenbus/xenbus_comms.h @@ -47,6 +47,4 @@ extern struct xenstore_domain_interface *xen_store_interface; extern int xen_store_evtchn; extern enum xenstore_init xen_store_domain_type; -extern const struct file_operations xen_xenbus_fops; - #endif /* _XENBUS_COMMS_H */ diff --git a/drivers/xen/xenbus/xenbus_dev_frontend.c b/drivers/xen/xenbus/xenbus_dev_frontend.c index c1010f01..a45e7f2 100644 --- a/drivers/xen/xenbus/xenbus_dev_frontend.c +++ b/drivers/xen/xenbus/xenbus_dev_frontend.c @@ -598,7 +598,7 @@ static unsigned int xenbus_file_poll(struct file *file, poll_table *wait) return 0; } -const struct file_operations xen_xenbus_fops = { +const static struct file_operations xen_xenbus_fops = { .read = xenbus_file_read, .write = xenbus_file_write, .open = xenbus_file_open, @@ -606,7 +606,6 @@ const struct file_operations xen_xenbus_fops = { .poll = xenbus_file_poll, .llseek = no_llseek, }; -EXPORT_SYMBOL_GPL(xen_xenbus_fops); static struct miscdevice xenbus_dev = { .minor = MISC_DYNAMIC_MINOR, diff --git a/drivers/xen/xenfs/super.c b/drivers/xen/xenfs/super.c index 8559a71..0f2e2cd 100644 --- a/drivers/xen/xenfs/super.c +++ b/drivers/xen/xenfs/super.c @@ -18,8 +18,6 @@ #include #include "xenfs.h" -#include "../privcmd.h" -#include "../xenbus/xenbus_comms.h" #include @@ -45,16 +43,16 @@ static const struct file_operations capabilities_file_ops = { static int xenfs_fill_super(struct super_block *sb, void *data, int silent) { static struct tree_descr xenfs_files[] = { - [2] = { "xenbus", &xen_xenbus_fops, S_IRUSR|S_IWUSR }, + [2] = { "xenbus", NULL, S_IFLNK | S_IRWXUGO, "/dev/xen/xenbus" }, { "capabilities", &capabilities_file_ops, S_IRUGO }, - { "privcmd", &xen_privcmd_fops, S_IRUSR|S_IWUSR }, + { "privcmd", NULL, S_IFLNK | S_IRWXUGO, "/dev/xen/privcmd" }, {""}, }; static struct tree_descr xenfs_init_files[] = { - [2] = { "xenbus", &xen_xenbus_fops, S_IRUSR|S_IWUSR }, + [2] = { "xenbus", NULL, S_IFLNK | S_IRWXUGO, "/dev/xen/xenbus" }, { "capabilities", &capabilities_file_ops, S_IRUGO }, - { "privcmd", &xen_privcmd_fops, S_IRUSR|S_IWUSR }, + { "privcmd", NULL, S_IFLNK | S_IRWXUGO, "/dev/xen/privcmd" }, { "xsd_kva", &xsd_kva_file_ops, S_IRUSR|S_IWUSR}, { "xsd_port", &xsd_port_file_ops, S_IRUSR|S_IWUSR}, #ifdef CONFIG_XEN_SYMS -- 2.1.4