FS#10536 - [initscripts] internal: save a pid from killall5
Attached to Project:
Arch Linux
Opened by Anton Fiuman (lexiw) - Friday, 30 May 2008, 02:16 GMT
Last edited by Eric Belanger (Snowman) - Thursday, 02 June 2011, 22:59 GMT
Opened by Anton Fiuman (lexiw) - Friday, 30 May 2008, 02:16 GMT
Last edited by Eric Belanger (Snowman) - Thursday, 02 June 2011, 22:59 GMT
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Details
Description:
A little patch to killall5 from the sysvinit package. This patch allow users to set a pid that will be omitted from the kill routine. Others distros have a similar patched killall5 but following another path. The way they implemented it need a command line parameter to be passed (killall5 -o omitpids). In this way a user can pass a list of pids to be omitted. The way i did it is a bit different because my needs were a little different: i still need my process to not be killed but i don't want to patch/modify /etc/rc.shutdown. This is the last step needed to make an initscripts-splash that doesn't conflict/replace with the official initscritps package. During shutdown splashy (or any other userspace splash system) get killed to early, this patch avoids this. How it works: export KILLALL5_OMITPID="splashy" /sbin/killall5 -15 /sbin/killall5 -9 The patch is very very small, i tried to make it as simple as possible to avoid bugs in a critical package. If KILLALL5_OMITPID isn't set or something goes wrong i return a safe pid (return getpid()). The patch is limited because i don't want to risk a bug, only one program is accepted. The "alternative" patch doesn't work with program names but directly with pids. I don't like it even if it's shorter because it's too error prone (a wrong variable set and atoi fails, maybe a rewrite using strtol...). How it works: export KILLALL5_OMITPID="`pidof splashy`" /sbin/killall5 -15 /sbin/killall5 -9 I'm using the first patch now and dismissed the alternative one. |
This task depends upon
Closed by Eric Belanger (Snowman)
Thursday, 02 June 2011, 22:59 GMT
Reason for closing: Implemented
Additional comments about closing: initscripts-2011.06.2-1
Thursday, 02 June 2011, 22:59 GMT
Reason for closing: Implemented
Additional comments about closing: initscripts-2011.06.2-1
My only thought is:
We can implement this two ways.
* Use the patch
* Replace rc.shutdown's killall5 call with a loop over all PIDs, doing the same sort of skip
Opinions?
Lets go for it. Do we want to use one of the above patches, or Ubuntu's? The curious thing is that the above patches only let you omit _one_ PID instead of a list (i.e. KILLALL5_OMITPID="1 17 343 342345")
If you want to modify rc.shutdown too we can avoid the getenv call and add the "-o list_of_pids" options. A program would write it's pid to a file if he want it to be omitted and a script will load it and pass the arguments to killall5.
Here's how it works in debian:
mkdir -p /lib/init/rw/sendsigs.omit.d
pidof $NAME >> /lib/init/rw/sendsigs.omit.d/splashy
Searching in google it seems that this problem affects just (userspace) splash systems and (userspace) filesystems. http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=476698 and https://bugs.launchpad.net/ubuntu/+source/sysvinit/+bug/87763, maybe the latter doesn't affects ArchLinux at all, correct me if I'm wrong.
Anyway, in the future we'll probably need to omit something else so it should be better to plan accordingly.
To sum it up:
My patch is smaller, safe but limited to one pid.
The Debian patch is more versatile and it should be safe too (it's in Debian and Ubuntu after all) although it's bigger.
Pros:
My patch doesn't require to modify rc.shutdown.
Debian patch is the right way to do things (-o omitpid is an options of pidof too...).
Cons:
My patch is dirty because i needed a workaround to NOT modify rc.shutdown.
Debian patch requires to modify rc.shutdown: load pids from a file (or files) and build the command line options to be passed to killall5.
I have ready a patch for rc.shutdown, i preferred the "file per script" way to make it possible for scripts that need to modify the list of pids at run time without race conditions.
The format is: /var/run/shutdown.omit.d/packagename
How it works:
mkdir -p /var/run/shutdown.omit.d/
pidof name > /var/run/shutdown.omit.d/name
or:
mkdir -p /var/run/shutdown.omit.d/
rm -f /var/run/shutdown.omit.d/name
ln -s /var/run/name.pid /var/run/shutdown.omit.d/name
I've attached a patch for the sysvinit PKGBUILD.
And as far as i can see, there already is an -o option (for “omit”) in the svn version of killall5 http://svn.savannah.gnu.org/viewvc/sysvinit/trunk/src/killall5.c?root=sysvinit&view=markup (scroll down to the bottom)
Edit: actually attached files
edit: corrected patch
edit: corrected again :-/ (can not delete - please use 3rd one)