Re: [PATCH] DevFS support for /dev/cpu/X/(cpuid|msr)

Ishan Jayawardena
2002-02-18T10:50:43Z

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Perhaps this will suit your taste better...

I'd love to extend this work to support Paul Russell's hotplug cpu work, but
I have absolutely no way at present to test it. (If some kind party would
like to donate a quad pentium 4 Xeon with hotplug cpu support, I'll be more
than happy to do so ;)

This is against 2.4.18-pre9-ac4 with devfs v199.9

Relevent comments, advise, improvisations, flames, welcome.

I. O. Jayawardena
.

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--- linux/fs/devfs/base.c Mon Feb 18 16:07:49 2002
+++ linux-ioj/fs/devfs/base.c Mon Feb 18 12:45:42 2002
@@ -631,6 +631,7 @@
#include <linux/init.h>
#include <linux/devfs_fs.h>
#include <linux/devfs_fs_kernel.h>
+#include <linux/threads.h>
#include <linux/smp_lock.h>
#include <linux/smp.h>
#include <linux/version.h>
@@ -1624,6 +1625,72 @@ devfs_handle_t devfs_register (devfs_han

/**
+ * devfs_register_per_cpu - register a device node across all
+ * cpu-specific directories.
+ * @leafname - the name of the device node
+ *
+ * All other parameters are for devfs_register(). Returns zero on success.
+ */
+
+int devfs_register_per_cpu (const char *leafname, unsigned int flags,
+ unsigned int major, unsigned int minor_start,
+ umode_t mode, void *ops, void *info)
+{
+ int i;
+ char *name;
+ char tmp[5] = { "0" }; /* FIXME: this string may overflow, but we don't know
+ the sizeof smp_num_cpus until we get it into a string */
+
+ if (smp_num_cpus > 1) sprintf (tmp, "%d", smp_num_cpus - 1);
+ name = kmalloc (strlen (leafname) + strlen (tmp) + sizeof (char) * 6,
+ GFP_KERNEL);
+ if (!name) return -ENOMEM;
+ for(i = 0; i < smp_num_cpus; i++) {
+ sprintf (name, "cpu/%d/%s", i, leafname);
+ if (!devfs_register (NULL, name, flags, major, minor_start + i,
+ mode, ops, info)) {
+ PRINTK ("(): devfs_register() failed.\n");
+ kfree (name);
+ return -EAGAIN;
+ }
+ }
+ kfree (name);
+ return 0;
+} /* End function devfs_register_per_cpu */
+
+
+/**
+ * devfs_unregister_per_cpu - unregister a node across /dev/cpu/
+ * @leafname - the name of the device node
+ *
+ * Unregisters a number of nodes (probably registered with
+ * devfs_register_per_cpu() )
+ */
+
+void devfs_unregister_per_cpu (const char *leafname)
+{
+ int i;
+ char *name;
+ char tmp[5] = { "0" };
+ devfs_handle_t dh;
+
+ if (smp_num_cpus > 1) sprintf (tmp, "%d", smp_num_cpus - 1);
+ name = kmalloc (strlen (leafname) + strlen (tmp) + sizeof (char) * 6,
+ GFP_KERNEL);
+ if (!name) return;
+ for (i = 0; i < smp_num_cpus; i++) {
+ sprintf (name, "cpu/%d/%s", i, leafname);
+ dh = _devfs_walk_path (NULL, name, strlen (name), 0);
+ if (!dh) {
+ kfree (name);
+ return;
+ }
+ devfs_unregister (dh);
+ }
+ kfree (name);
+} /* End function devfs_unregister_per_cpu */
+
+/**
* _devfs_unhook - Unhook a device entry from its parents list
* @de: The entry to unhook.
*
@@ -2355,7 +2422,9 @@ __setup("devfs=", devfs_setup);

EXPORT_SYMBOL(devfs_put);
EXPORT_SYMBOL(devfs_register);
+EXPORT_SYMBOL(devfs_register_per_cpu);
EXPORT_SYMBOL(devfs_unregister);
+EXPORT_SYMBOL(devfs_unregister_per_cpu);
EXPORT_SYMBOL(devfs_mk_symlink);
EXPORT_SYMBOL(devfs_mk_dir);
EXPORT_SYMBOL(devfs_get_handle);
@@ -3172,6 +3241,17 @@ static int devfs_mknod (struct inode *di
inode->i_uid, inode->i_gid, fs_info, 0);
return 0;
} /* End Function devfs_mknod */
+
+void devfs_mk_dir_per_cpu (void)
+{
+ int i;
+ char name[7];
+
+ for (i = 0; i < smp_num_cpus; i++) {
+ sprintf (name, "cpu/%d", i);
+ devfs_mk_dir (NULL, name, NULL);
+ }
+}

static int devfs_readlink (struct dentry *dentry, char *buffer, int buflen)
{
--- linux/include/linux/devfs_fs_kernel.h Mon Feb 18 16:05:21 2002
+++ linux-ioj/include/linux/devfs_fs_kernel.h Mon Feb 18 14:08:38 2002
@@ -73,12 +73,17 @@ extern devfs_handle_t devfs_register (de
unsigned int flags,
unsigned int major, unsigned int minor,
umode_t mode, void *ops, void *info);
+extern int devfs_register_per_cpu (const char *leafname, unsigned int flags,
+ unsigned int major, unsigned int minor_start,
+ umode_t mode, void *ops, void *info);
extern void devfs_unregister (devfs_handle_t de);
+extern void devfs_unregister_per_cpu (const char *leafname);
extern int devfs_mk_symlink (devfs_handle_t dir, const char *name,
unsigned int flags, const char *link,
devfs_handle_t *handle, void *info);
extern devfs_handle_t devfs_mk_dir (devfs_handle_t dir, const char *name,
void *info);
+extern void devfs_mk_dir_per_cpu (void);
extern devfs_handle_t devfs_get_handle (devfs_handle_t dir, const char *name,
unsigned int major,unsigned int minor,
char type, int traverse_symlinks);
@@ -149,9 +154,20 @@ static inline devfs_handle_t devfs_regis
{
return NULL;
}
+static inline int devfs_register_per_cpu (const char *name,
+ unsigned int flags,
+ unsigned int major,
+ unsigned int minor_start,
+ umode_t mode, void *ops, void *info);
+{
+ return NULL;
+}
static inline void devfs_unregister (devfs_handle_t de)
{
- return;
+}
+static inline void devfs_unregister_per_cpu (const char *name)
+{
+ return NULL;
}
static inline int devfs_mk_symlink (devfs_handle_t dir, const char *name,
unsigned int flags, const char *link,
@@ -163,6 +179,9 @@ static inline devfs_handle_t devfs_mk_di
const char *name, void *info)
{
return NULL;
+}
+static inline void devfs_mk_dir_per_cpu (void)
+{
}
static inline devfs_handle_t devfs_get_handle (devfs_handle_t dir,
const char *name,
--- linux/init/main.c Mon Feb 18 16:07:37 2002
+++ linux-ioj/init/main.c Sun Feb 17 23:26:43 2002
@@ -497,9 +497,13 @@ unsigned long wait_init_idle;
static void __init smp_init(void)
{
APIC_init_uniprocessor();
+
+ devfs_mk_dir_per_cpu();
}
#else
-#define smp_init() do { } while (0)
+#define smp_init() do { \
+ devfs_mk_dir_per_cpu(); \
+ } while (0)
#endif

#else
@@ -523,6 +527,8 @@ static void __init smp_init(void)
barrier();
}
printk("All processors have done init_idle\n");
+
+ devfs_mk_dir_per_cpu();
}

#endif
--- linux/arch/i386/kernel/cpuid.c Thu Oct 11 12:04:57 2001
+++ linux-ioj/arch/i386/kernel/cpuid.c Mon Feb 18 15:19:32 2002
@@ -32,6 +32,7 @@
#include <linux/errno.h>
#include <linux/fcntl.h>
#include <linux/init.h>
+#include <linux/devfs_fs_kernel.h>
#include <linux/poll.h>
#include <linux/smp.h>
#include <linux/major.h>
@@ -140,24 +141,26 @@ static struct file_operations cpuid_fops
open: cpuid_open,
};

-int __init cpuid_init(void)
+static int __init cpuid_init(void)
{
- if (register_chrdev(CPUID_MAJOR, "cpu/cpuid", &cpuid_fops)) {
+ 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;
}

- return 0;
+ return devfs_register_per_cpu("cpuid", DEVFS_FL_DEFAULT, CPUID_MAJOR, 0,
+ S_IFCHR | S_IRUSR | S_IRGRP, &cpuid_fops, NULL);
}

void __exit cpuid_exit(void)
{
- unregister_chrdev(CPUID_MAJOR, "cpu/cpuid");
+ devfs_unregister_chrdev(CPUID_MAJOR, "cpu/%d/cpuid");
+ devfs_unregister_per_cpu("cpuid");
}

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

EXPORT_NO_SYMBOLS;

--- linux/arch/i386/kernel/msr.c Thu Oct 11 12:04:57 2001
+++ linux-ioj/arch/i386/kernel/msr.c Mon Feb 18 15:19:05 2002
@@ -31,6 +31,7 @@
#include <linux/errno.h>
#include <linux/fcntl.h>
#include <linux/init.h>
+#include <linux/devfs_fs_kernel.h>
#include <linux/poll.h>
#include <linux/smp.h>
#include <linux/major.h>
@@ -248,24 +249,26 @@ static struct file_operations msr_fops =
open: msr_open,
};

-int __init msr_init(void)
+static int __init msr_init(void)
{
- if (register_chrdev(MSR_MAJOR, "cpu/msr", &msr_fops)) {
+ 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;
}

- return 0;
+ return devfs_register_per_cpu("msr", DEVFS_FL_DEFAULT, MSR_MAJOR, 0,
+ S_IFCHR | S_IRUSR | S_IRGRP, &msr_fops, NULL);
}

void __exit msr_exit(void)
{
- unregister_chrdev(MSR_MAJOR, "cpu/msr");
+ devfs_unregister_chrdev(MSR_MAJOR, "cpu/%d/msr");
+ devfs_unregister_per_cpu("msr");
}

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

EXPORT_NO_SYMBOLS;