| Message ID | 1467137167-28546-3-git-send-email-david.vrabel@citrix.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 28/06/16 20:06, David Vrabel wrote: > /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 <david.vrabel@citrix.com> > --- > v2: > - remove unneeded includes > --- I think you should make xen_xenbus_fops and xen_privcmd_fops static now that they are no longer referenced by super.c Juergen > drivers/xen/xenfs/super.c | 10 ++++------ > 1 file changed, 4 insertions(+), 6 deletions(-) > > 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 <xen/xen.h> > > #include "xenfs.h" > -#include "../privcmd.h" > -#include "../xenbus/xenbus_comms.h" > > #include <asm/xen/hypervisor.h> > > @@ -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 >
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 <xen/xen.h> #include "xenfs.h" -#include "../privcmd.h" -#include "../xenbus/xenbus_comms.h" #include <asm/xen/hypervisor.h> @@ -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
/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 <david.vrabel@citrix.com> --- v2: - remove unneeded includes --- drivers/xen/xenfs/super.c | 10 ++++------ 1 file changed, 4 insertions(+), 6 deletions(-)