hotplug: update xencommons script to run only when needed

PATCH Superseded Olaf Hering 3 participants 9 messages Aug 12, 2011 – Aug 31, 2011

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Olaf Hering

author

2011-08-12 07:11 UTC #0 lore raw

PATCH 1/1 hotplug: update xencommons script to run only when needed

# HG changeset patch
# User Olaf Hering <[email protected]>
# Date 1313133097 -7200
# Node ID 0e95f2c754bf526a89bb8a097959e6c970e9b5b7 # Parent 1f08b380d4386cdd6714786a9163e5f51aecab5d
hotplug: update xencommons script to run only when needed

Currently xencommons prints an error if /proc/xen/capabilities does not exist when started on a non-xen kernel.

Update the xencommons script to run only when needed:
- do not run if /proc/xen does not exist
- check if /proc/xen/capabilities exists before doing the grep for dom0
- use variable for /proc/xen/capabilities
- use grep -q instead of stdout redirection when looking for xenfs, its already used later

Signed-off-by Olaf Hering <[email protected]>

tools/hotplug/Linux/init.d/xencommons +16 -4

diff -r 1f08b380d438 -r 0e95f2c754bf tools/hotplug/Linux/init.d/xencommons
@@ -27,17 +27,29 @@ fi
 test -f $xencommons_config/xencommons && . $xencommons_config/xencommons
 
 XENCONSOLED_PIDFILE=/var/run/xenconsoled.pid
+XEN_CAPABILITIES=/proc/xen/capabilities
 shopt -s extglob
 
+# not running in Xen dom0 or domU
+if ! test -d /proc/xen ; then
+	exit 0
+fi
+
+# mount xenfs in dom0 or domU with a pv_ops kernel
 if test "x$1" = xstart && \
-     test -d /proc/xen && \
-   ! test -f /proc/xen/capabilities && \
-   ! grep '^xenfs ' /proc/mounts >/dev/null;
+   ! test -f $XEN_CAPABILITIES && \
+   ! grep -q '^xenfs ' /proc/mounts ;
 then
 	mount -t xenfs xenfs /proc/xen
 fi
 
-if ! grep -q "control_d" /proc/xen/capabilities ; then
+# run this script only in dom0:
+# no capabilities file in xenlinux kernel
+if ! test -f $XEN_CAPABILITIES ; then
+	exit 0
+fi
+# empty capabilities file in pv_ops kernel
+if ! grep -q "control_d" $XEN_CAPABILITIES ; then
 	exit 0
 fi

Ian Jackson

2011-08-25 15:15 UTC #1 lore raw

Olaf Hering writes ("[Xen-devel] [PATCH] hotplug: update xencommons script to run only when needed"):

Quoted 1 line

Update the xencommons script to run only when needed:

Thanks. I like most of this. But:

Quoted 1 line

- use variable for /proc/xen/capabilities

Why ? Is this going to move ? I think if it moves we have other problems, since it's part of the published /proc interface from Xen-enabled kernels.

Ian.

Olaf Hering

author

2011-08-25 15:24 UTC #2 lore raw

Quoted 10 lines · Ian Jackson

Olaf Hering writes ("[Xen-devel] [PATCH] hotplug: update xencommons script to run only when needed"):
Quoted 1 line
Update the xencommons script to run only when needed:
Thanks. I like most of this. But:
Quoted 1 line
- use variable for /proc/xen/capabilities
Why ? Is this going to move ? I think if it moves we have other problems, since it's part of the published /proc interface from Xen-enabled kernels.

There is no special reason for the variable.
Do you want me to send a patch without the new variable?

Olaf

Ian Jackson

2011-08-25 15:34 UTC #3 lore raw

Olaf Hering writes ("Re: [Xen-devel] [PATCH] hotplug: update xencommons script to run only when needed"):

Quoted 1 line

There is no special reason for the variable.

Right.

Quoted 1 line

Do you want me to send a patch without the new variable?

If you like, or I can just take it out myself.

Ian.

Olaf Hering

author

2011-08-26 09:10 UTC #4 lore raw

PATCH v2 1/1 hotplug: update xencommons script to run only when needed

# HG changeset patch
# Parent 227130622561e20136a1ef56201fe65ead5a76e8
hotplug: update xencommons script to run only when needed

Currently xencommons prints an error if /proc/xen/capabilities does not exist when started on a non-xen kernel.

Update the xencommons script to run only when needed:
- do not run if /proc/xen does not exist
- check if /proc/xen/capabilities exists before doing the grep for dom0
- use grep -q instead of stdout redirection when looking for xenfs

Signed-off-by Olaf Hering <[email protected]>

tools/hotplug/Linux/init.d/xencommons +13 -2

diff -r 227130622561 tools/hotplug/Linux/init.d/xencommons
@@ -29,14 +29,25 @@ test -f $xencommons_config/xencommons &&
 XENCONSOLED_PIDFILE=/var/run/xenconsoled.pid
 shopt -s extglob
 
+# not running in Xen dom0 or domU
+if ! test -d /proc/xen ; then
+	exit 0
+fi
+
+# mount xenfs in dom0 or domU with a pv_ops kernel
 if test "x$1" = xstart && \
-     test -d /proc/xen && \
    ! test -f /proc/xen/capabilities && \
-   ! grep '^xenfs ' /proc/mounts >/dev/null;
+   ! grep -q '^xenfs ' /proc/mounts ;
 then
 	mount -t xenfs xenfs /proc/xen
 fi
 
+# run this script only in dom0:
+# no capabilities file in xenlinux kernel
+if ! test -f /proc/xen/capabilities ; then
+	exit 0
+fi
+# empty capabilities file in pv_ops kernel
 if ! grep -q "control_d" /proc/xen/capabilities ; then
 	exit 0
 fi

Jeremy Fitzhardinge

2011-08-20 00:49 UTC #5 lore raw

PATCH 2/2 Load gntdev and evtchn if they're modular.

Signed-off-by Jeremy Fitzhardinge <[email protected]>

tools/hotplug/Linux/init.d/xencommons +10 -4

diff -r cfb49fe940fd -r 81f75ed45ec2 tools/hotplug/Linux/init.d/xencommons
@@ -29,12 +29,18 @@
 XENCONSOLED_PIDFILE=/var/run/xenconsoled.pid
 shopt -s extglob
 
-if [ "x$1" = xstart -a -d /proc/xen -a \
-    ! -f /proc/xen/capabilities ] && \
-    ! grep -qw '^xenfs' /proc/mounts; then
-	mount -t xenfs xenfs /proc/xen
+[ -d /proc/xen ] || exit 0	# Xen not present; exit quietly
+
+if [ "x$1" = xstart ]; then
+	# Mount /proc/xen if needed
+	[ -f /proc/xen/capabilities ] || mount -t xenfs xenfs /proc/xen
+
+	# Make sure evtchn and gntdev are loaded if present
+	grep -q "xen/evtchn" /proc/misc || modprobe xen-evtchn
+	grep -q "xen/gntdev" /proc/misc || modprobe xen-gntdev
 fi
 
+# Done here if this isn't a control domain
 if ! grep -q "control_d" /proc/xen/capabilities ; then
 	exit 0
 fi

Ian Jackson

2011-08-30 16:46 UTC #6 lore raw

Re: [PATCH 2/2] Load gntdev and evtchn if they're modular. [and 1 more messages]

Jeremy Fitzhardinge writes ("[Xen-devel] [PATCH 2/2] Load gntdev and evtchn if they're modular."):

Quoted 4 lines

tools/hotplug/Linux/init.d/xencommons +0 -4

-if [ "x$1" = xstart -a -d /proc/xen -a \
-    ! -f /proc/xen/capabilities ] && \
-    ! grep -qw '^xenfs' /proc/mounts; then
-	mount -t xenfs xenfs /proc/xen

tools/hotplug/Linux/init.d/xencommons line 41

Quoted 10 lines

tools/hotplug/Linux/init.d/xencommons +9 -0

+[ -d /proc/xen ] || exit 0	# Xen not present; exit quietly
+
+if [ "x$1" = xstart ]; then
+	# Mount /proc/xen if needed
+	[ -f /proc/xen/capabilities ] || mount -t xenfs xenfs /proc/xen
+
+	# Make sure evtchn and gntdev are loaded if present
+	grep -q "xen/evtchn" /proc/misc || modprobe xen-evtchn
+	grep -q "xen/gntdev" /proc/misc || modprobe xen-gntdev
 fi

I'd be inclined to accept this although because I didn't like your previous patch, it doesn't apply.

Olaf Hering writes ("[Xen-devel] [PATCH v2] hotplug: update xencommons script to run only when needed"):

Review

Quoted 4 lines

(quoted diff) +4 -0

+# not running in Xen dom0 or domU
+if ! test -d /proc/xen ; then
+	exit 0
+fi

This part is fine.

Review

Quoted 3 lines

(quoted diff) +1 -1

+# mount xenfs in dom0 or domU with a pv_ops kernel
 if test "x$1" = xstart && \
-     test -d /proc/xen && \

Fine.

Review

Quoted 6 lines

    ! test -f /proc/xen/capabilities && \

(quoted diff) +1 -1

-   ! grep '^xenfs ' /proc/mounts >/dev/null;
+   ! grep -q '^xenfs ' /proc/mounts ;
 then
 	mount -t xenfs xenfs /proc/xen
 fi

As I said to Jeremy, I'm not sure I want style changes. I'm not convinced of the huge usefulness of this one either.

Review

Quoted 9 lines

(quoted diff) +6 -0

+# run this script only in dom0:
+# no capabilities file in xenlinux kernel
+if ! test -f /proc/xen/capabilities ; then
+	exit 0
+fi
+# empty capabilities file in pv_ops kernel
 if ! grep -q "control_d" /proc/xen/capabilities ; then
 	exit 0
 fi

If /proc/xen/capabilities is missing, what does it mean ? Do domU kernels really not provide that file ? Also these two ifs would be better combined.

Ian.

Olaf Hering

author

2011-08-30 18:12 UTC #7 lore raw

Re: [PATCH 2/2] Load gntdev and evtchn if they're modular. [and 1 more messages]

Quoted 11 lines · Ian Jackson

Review

Quoted 9 lines

(quoted diff) +6 -0

+# run this script only in dom0:
+# no capabilities file in xenlinux kernel
+if ! test -f /proc/xen/capabilities ; then
+	exit 0
+fi
+# empty capabilities file in pv_ops kernel
 if ! grep -q "control_d" /proc/xen/capabilities ; then
 	exit 0
 fi

If /proc/xen/capabilities is missing, what does it mean ?

It means a domU with xenlinux PV drivers loaded, in that case the script has to do nothing.

Quoted 2 lines

kernels really not provide that file ? Also these two ifs would be better combined.

How would that look like? First the file is not there, so grep will print an error - thats what my patch tries to fix. Second the file is there and may indicate a dom0.

Olaf

Ian Jackson

2011-08-31 16:02 UTC #8 lore raw

Re: [PATCH 2/2] Load gntdev and evtchn if they're modular. [and 1 more messages]

Olaf Hering writes ("Re: [Xen-devel] [PATCH 2/2] Load gntdev and evtchn if they're modular. [and 1 more messages]"):

Quoted 2 lines

How would that look like? First the file is not there, so grep will print an error - thats what my patch tries to fix.

If you write
false && true
the shell does not execute true.

Ian.