Hello Simon, On 05/08/2016 07:04 PM, Simon Nagl wrote: > Hello mkt, > > I tried to poll for changes of /proc/mounts via select(). > > This does not work as expected. I found more inforamtion on stackoverflow. > > http://stackoverflow.com/questions/5070801/monitoring-mount-point-changes-via-proc-mounts > > From 41d047b5df0dc759be621d0af1e45e5b6fba0028 Mon Sep 17 00:00:00 2001 > From: Simon Nagl <simonnagl@xxxxxxx> > Date: Sun, 8 May 2016 18:49:36 +0200 > Subject: [PATCH] proc.5: Correct polling of mounts via select() > > Change of mounts can be polled with select via exceptfds, not readfds. > --- > man5/proc.5 | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/man5/proc.5 b/man5/proc.5 > index cb85b9b..a377d06 100644 > --- a/man5/proc.5 > +++ b/man5/proc.5 > @@ -47,6 +47,7 @@ > .\" and /proc/[pid]/fdinfo/*. > .\" 2008-06-19, mtk, Documented /proc/[pid]/status. > .\" 2008-07-15, mtk, added /proc/config.gz > +.\" 2016-05-08, Simon Nagl (simonnagl@xxxxxxx), corrected > /proc/[pid]/mounts > .\" > .\" FIXME . cross check against Documentation/filesystems/proc.txt > .\" to see what information could be imported from that file > @@ -1186,7 +1187,7 @@ Since kernel version 2.6.15, this file is pollable: > after opening the file for reading, a change in this file > (i.e., a filesystem mount or unmount) causes > .BR select (2) > -to mark the file descriptor as readable, and > +to mark the file descriptor as an exception, and > .BR poll (2) > and > .BR epoll_wait (2) Thanks for this report. I applied a somewhat more detailed patch, as below. Cheers, Michael diff --git a/man7/namespaces.7 b/man7/namespaces.7 index a736711..3de8f5f 100644 --- a/man7/namespaces.7 +++ b/man7/namespaces.7 @@ -297,11 +297,20 @@ Since kernel version 2.6.15, this file is pollable: after opening the file for reading, a change in this file (i.e., a filesystem mount or unmount) causes .BR select (2) -to mark the file descriptor as readable, and +to mark the file descriptor as having an exceptional condition, and .BR poll (2) and .BR epoll_wait (2) -mark the file as having an error condition. +mark the file as having a priority event +.RB ( POLLPRI ). +(Before Linux 2.6.30, +a change in this file was indicated by the file descriptor +being marked as readable for +.BR select (2), +and being marked as having an error condition for +.BR poll (2) +and +.BR epoll_wait (2).) The .IR /proc/[pid]/mountstats -- Michael Kerrisk Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/ Linux/UNIX System Programming Training: http://man7.org/training/ -- To unsubscribe from this list: send the line "unsubscribe linux-man" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
