Re: [ANNOUNCE] HotPlug CPU patch against 2.4.5

[Greg KH]

On Sat, Jun 16, 2001 at 11:29:00PM +1000, Rusty Russell wrote:
> Hi all,
> 
>       http://sourceforge.net/projects/lhcs/
> 
>       Version 0.3 (untested) of the HotPlug CPU Patch is out, with
> ia64 and x86 support.

Here's a patch to the patch that adds /sbin/hotplug support (sorry, I
couldn't resist...)

It also fixes a '}' problem in fs/proc/proc_misc.c

thanks,

greg k-h

diff -Naur -X /home/greg/linux/dontdiff linux-2.4.5-hotplug/fs/proc/proc_misc.c 
linux-2.4.5-hotplug-greg/fs/proc/proc_misc.c
--- linux-2.4.5-hotplug/fs/proc/proc_misc.c     Tue Jun 26 09:23:00 2001
+++ linux-2.4.5-hotplug-greg/fs/proc/proc_misc.c        Tue Jun 26 09:43:57 2001
@@ -295,6 +295,7 @@
                        jif - (  kstat.per_cpu_user[i] \
                                   + kstat.per_cpu_nice[i] \
                                   + kstat.per_cpu_system[i]));
+       }
        len += sprintf(page + len,
                "page %u %u\n"
                 "swap %u %u\n"
diff -Naur -X /home/greg/linux/dontdiff linux-2.4.5-hotplug/kernel/cpu.c 
linux-2.4.5-hotplug-greg/kernel/cpu.c
--- linux-2.4.5-hotplug/kernel/cpu.c    Tue Jun 26 09:23:00 2001
+++ linux-2.4.5-hotplug-greg/kernel/cpu.c       Tue Jun 26 10:00:45 2001
@@ -8,6 +8,7 @@
 #include <linux/notifier.h>
 #include <linux/sched.h>
 #include <linux/sched.h>
+#include <linux/kmod.h>                /* for hotplug_path */
 #include <asm/semaphore.h>
 #include <asm/uaccess.h>
 
@@ -17,6 +18,38 @@
 
 static struct notifier_block *cpu_chain = NULL;
 
+#ifdef CONFIG_HOTPLUG
+/* Notify userspace when a cpu event occurs,
+ * by running '/sbin/hotplug cpu' with certain
+ * environment variables set.
+ */
+static int cpu_run_sbin_hotplug(unsigned int cpu, char *action)
+{
+       char *argv[3], *envp[5], cpu_str[12], action_str[32];
+       int i;
+
+       sprintf(cpu_str, "CPU=%d", cpu);
+       sprintf(action_str, "ACTION=%s", action);
+
+       i = 0;
+       argv[i++] = hotplug_path;
+       argv[i++] = "cpu";
+       argv[i] = 0;
+
+       i = 0;
+       /* minimal command environment */
+       envp [i++] = "HOME=/";
+       envp [i++] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin";
+       envp [i++] = cpu_str;
+       envp [i++] = action_str;
+       envp [i] = 0;
+
+       return call_usermodehelper(argv [0], argv, envp);
+}
+#else
+#define cpu_run_sbin_hotplug(cpu, action) ({ 0; })
+#endif
+
 /* Should really be in a header somewhere. */
 asmlinkage long sys_sched_get_priority_max(int policy);
 
@@ -120,6 +153,8 @@
        /* Die, CPU, die! */
        __cpu_die(cpu);
 
+       cpu_run_sbin_hotplug(cpu, "remove");
+
  out:
        up(&cpucontrol);
        return ret;
@@ -145,6 +180,8 @@
        /* Friendly to make sure everyone knows it's up before we
           return */
        __synchronize_kernel();
+
+       cpu_run_sbin_hotplug(cpu, "add");
 
  out:
        up(&cpucontrol);