From kosaki.motohiro@jp.fujitsu.com Thu Apr 9 14:36:15 2009 From: KOSAKI Motohiro Date: Thu, 9 Apr 2009 13:57:59 +0900 (JST) Subject: proc: mounts_poll() make consistent to mdstat_poll To: Neil Brown , Greg Kroah-Hartman , Al Viro , Ram Pai , Miklos Szeredi Cc: kosaki.motohiro@jp.fujitsu.com Message-ID: <20090409135633.B3E9.A69D9226@jp.fujitsu.com> In recently sysfs_poll discussion, Neil Brown pointed out /proc/mounts also should be fixed. SUSv3 says "Regular files shall always poll TRUE for reading and writing". see http://www.opengroup.org/onlinepubs/009695399/functions/poll.html Then, mounts_poll()'s default should be "POLLIN | POLLRDNORM". it mean always readable. In addition, event trigger should use "POLLERR | POLLPRI" instead POLLERR. it makes consistent to mdstat_poll() and sysfs_poll(). and, select(2) can handle POLLPRI easily. Reported-by: Neil Brown Signed-off-by: KOSAKI Motohiro Cc: Ram Pai Cc: Miklos Szeredi Cc: Al Viro Signed-off-by: Greg Kroah-Hartman --- fs/proc/base.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) --- a/fs/proc/base.c +++ b/fs/proc/base.c @@ -648,14 +648,14 @@ static unsigned mounts_poll(struct file { struct proc_mounts *p = file->private_data; struct mnt_namespace *ns = p->ns; - unsigned res = 0; + unsigned res = POLLIN | POLLRDNORM; poll_wait(file, &ns->poll, wait); spin_lock(&vfsmount_lock); if (p->event != ns->event) { p->event = ns->event; - res = POLLERR; + res |= POLLERR | POLLPRI; } spin_unlock(&vfsmount_lock);