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SubjectRe: [PATCH] DevFS support for /dev/cpu/X/(cpuid|msr)
Okey dokey,

Please find attached a second, better patch to add devfs support to the i386
cpuid and msr drivers. Now it doesn't nuke the cpu/X directories on
unloading and only enumerates CPUs based on smp_num_cpus instead of NR_CPUS.

Cheers

Matt
--
"Phased plasma rifle in a forty-watt range?"
"Hey, just what you see, pal"
diff -ur linux-2.4.17.orig/arch/i386/kernel/cpuid.c linux-2.4.17/arch/i386/kernel/cpuid.c
--- linux-2.4.17.orig/arch/i386/kernel/cpuid.c Sat Jan 5 19:20:08 2002
+++ linux-2.4.17/arch/i386/kernel/cpuid.c Sun Jan 6 20:29:07 2002
@@ -23,6 +23,11 @@
*
* This driver uses /dev/cpu/%d/cpuid where %d is the minor number, and on
* an SMP box will direct the access to CPU %d.
+ *
+ * ChangeLog
+ *
+ * 2002-01-06 Matt Dainty <matt@bodgit-n-scarper.com>
+ * Added support for devfs
*/

#include <linux/module.h>
@@ -35,12 +40,16 @@
#include <linux/poll.h>
#include <linux/smp.h>
#include <linux/major.h>
+#include <linux/threads.h>
+#include <linux/devfs_fs_kernel.h>

#include <asm/processor.h>
#include <asm/msr.h>
#include <asm/uaccess.h>
#include <asm/system.h>

+static devfs_handle_t devfs_handle[NR_CPUS];
+
#ifdef CONFIG_SMP

struct cpuid_command {
@@ -140,24 +149,40 @@
open: cpuid_open,
};

-int __init cpuid_init(void)
+static int __init cpuid_init(void)
{
- if (register_chrdev(CPUID_MAJOR, "cpu/cpuid", &cpuid_fops)) {
+ int i;
+ char name[16];
+
+ if (devfs_register_chrdev(CPUID_MAJOR, "cpu/%d/cpuid", &cpuid_fops)) {
printk(KERN_ERR "cpuid: unable to get major %d for cpuid\n",
CPUID_MAJOR);
return -EBUSY;
}
+ for(i = 0; i < smp_num_cpus; i++) {
+ sprintf(name, "cpu/%d/cpuid", i);
+ if ((devfs_handle[i] = devfs_register(NULL, name, DEVFS_FL_DEFAULT,
+ CPUID_MAJOR, i,
+ S_IFCHR | S_IRUSR | S_IRGRP,
+ &cpuid_fops, NULL)) == NULL) {
+ printk(KERN_ERR "cpuid: failed to devfs_register()\n");
+ }
+ }

return 0;
}

-void __exit cpuid_exit(void)
+static void __exit cpuid_exit(void)
{
- unregister_chrdev(CPUID_MAJOR, "cpu/cpuid");
+ int i;
+
+ for(i = 0; i < smp_num_cpus; i++)
+ devfs_unregister(devfs_handle[i]);
+ devfs_unregister_chrdev(CPUID_MAJOR, "cpu/%d/cpuid");
}

module_init(cpuid_init);
-module_exit(cpuid_exit)
+module_exit(cpuid_exit);

EXPORT_NO_SYMBOLS;

diff -ur linux-2.4.17.orig/arch/i386/kernel/msr.c linux-2.4.17/arch/i386/kernel/msr.c
--- linux-2.4.17.orig/arch/i386/kernel/msr.c Sat Jan 5 19:20:08 2002
+++ linux-2.4.17/arch/i386/kernel/msr.c Sun Jan 6 20:29:19 2002
@@ -22,6 +22,11 @@
*
* This driver uses /dev/cpu/%d/msr where %d is the minor number, and on
* an SMP box will direct the access to CPU %d.
+ *
+ * ChangeLog
+ *
+ * 2002-01-06 Matt Dainty <matt@bodgit-n-scarper.com>
+ * Added support for devfs
*/

#include <linux/module.h>
@@ -34,12 +39,16 @@
#include <linux/poll.h>
#include <linux/smp.h>
#include <linux/major.h>
+#include <linux/threads.h>
+#include <linux/devfs_fs_kernel.h>

#include <asm/processor.h>
#include <asm/msr.h>
#include <asm/uaccess.h>
#include <asm/system.h>

+static devfs_handle_t devfs_handle[NR_CPUS];
+
/* Note: "err" is handled in a funny way below. Otherwise one version
of gcc or another breaks. */

@@ -248,24 +257,40 @@
open: msr_open,
};

-int __init msr_init(void)
+static int __init msr_init(void)
{
- if (register_chrdev(MSR_MAJOR, "cpu/msr", &msr_fops)) {
+ int i;
+ char name[16];
+
+ if (devfs_register_chrdev(MSR_MAJOR, "cpu/%d/msr", &msr_fops)) {
printk(KERN_ERR "msr: unable to get major %d for msr\n",
MSR_MAJOR);
return -EBUSY;
}
+ for(i = 0; i < smp_num_cpus; i++) {
+ sprintf(name, "cpu/%d/msr", i);
+ if ((devfs_handle[i] = devfs_register(NULL, name, DEVFS_FL_DEFAULT,
+ MSR_MAJOR, i,
+ S_IFCHR | S_IRUSR | S_IRGRP | S_IWUSR,
+ &msr_fops, NULL)) == NULL) {
+ printk(KERN_ERR "msr: failed to devfs_register()\n");
+ }
+ }

return 0;
}

-void __exit msr_exit(void)
+static void __exit msr_exit(void)
{
- unregister_chrdev(MSR_MAJOR, "cpu/msr");
+ int i;
+
+ for(i = 0; i < smp_num_cpus; i++)
+ devfs_unregister(devfs_handle[i]);
+ devfs_unregister_chrdev(MSR_MAJOR, "cpu/%d/msr");
}

module_init(msr_init);
-module_exit(msr_exit)
+module_exit(msr_exit);

EXPORT_NO_SYMBOLS;
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