Hi Linus,
Recently Alan Cox commented in the context of 2.4 todo list that the
drivers should be checked for mistakingly assuming that exclusive open
means single threaded read/write. So I did this work for my own driver -
hence the patch below.
The patch does:
a) removes exclusive open concept from the driver (it's not needed)
b) removes the status bitmap and ->release() method
c) adds a rw semaphore to serialize read/write/ioctl as required
d) removes global kernel lock usage
e) some cleanups not worth mentioning
Regards,
Tigran
--- linux/arch/i386/kernel/microcode.c Tue Aug 1 09:45:36 2000
+++ work/arch/i386/kernel/microcode.c Thu Aug 3 17:37:12 2000
@@ -1,13 +1,14 @@
/*
- * CPU Microcode Update interface for Linux
+ * Intel CPU Microcode Update driver for Linux
*
* Copyright (C) 2000 Tigran Aivazian
*
* This driver allows to upgrade microcode on Intel processors
- * belonging to P6 family - PentiumPro, Pentium II, Pentium III etc.
+ * belonging to P6 family - PentiumPro, Pentium II,
+ * Pentium III, Xeon etc.
*
* Reference: Section 8.10 of Volume III, Intel Pentium III Manual,
- * Order Number 243192 or download from:
+ * Order Number 243192 or free download from:
*
* http://developer.intel.com/design/pentiumii/manuals/243192.htm
*
@@ -18,28 +19,31 @@
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*
- * 1.0 16 February 2000, Tigran Aivazian <tigran@sco.com>
+ * 1.0 16 Feb 2000, Tigran Aivazian <tigran@sco.com>
* Initial release.
- * 1.01 18 February 2000, Tigran Aivazian <tigran@sco.com>
+ * 1.01 18 Feb 2000, Tigran Aivazian <tigran@sco.com>
* Added read() support + cleanups.
- * 1.02 21 February 2000, Tigran Aivazian <tigran@sco.com>
+ * 1.02 21 Feb 2000, Tigran Aivazian <tigran@sco.com>
* Added 'device trimming' support. open(O_WRONLY) zeroes
* and frees the saved copy of applied microcode.
- * 1.03 29 February 2000, Tigran Aivazian <tigran@sco.com>
+ * 1.03 29 Feb 2000, Tigran Aivazian <tigran@sco.com>
* Made to use devfs (/dev/cpu/microcode) + cleanups.
- * 1.04 06 June 2000, Simon Trimmer <simon@veritas.com>
+ * 1.04 06 Jun 2000, Simon Trimmer <simon@veritas.com>
* Added misc device support (now uses both devfs and misc).
* Added MICROCODE_IOCFREE ioctl to clear memory.
- * 1.05 09 June 2000, Simon Trimmer <simon@veritas.com>
+ * 1.05 09 Jun 2000, Simon Trimmer <simon@veritas.com>
* Messages for error cases (non intel & no suitable microcode).
+ * 1.06 03 Aug 2000, Tigran Aivazian <tigran@veritas.com>
+ * Removed ->release(). Removed exclusive open and status bitmap.
+ * Added microcode_rwsem to serialize read()/write()/ioctl().
+ * Removed global kernel lock usage.
*/
#include <linux/init.h>
-#include <linux/slab.h>
#include <linux/sched.h>
#include <linux/module.h>
+#include <linux/malloc.h>
#include <linux/vmalloc.h>
-#include <linux/smp_lock.h>
#include <linux/miscdevice.h>
#include <linux/devfs_fs_kernel.h>
@@ -47,7 +51,7 @@
#include <asm/uaccess.h>
#include <asm/processor.h>
-#define MICROCODE_VERSION "1.05"
+#define MICROCODE_VERSION "1.06"
MODULE_DESCRIPTION("Intel CPU (P6) microcode update driver");
MODULE_AUTHOR("Tigran Aivazian <tigran@veritas.com>");
@@ -55,28 +59,20 @@
/* VFS interface */
static int microcode_open(struct inode *, struct file *);
-static int microcode_release(struct inode *, struct file *);
static ssize_t microcode_read(struct file *, char *, size_t, loff_t *);
static ssize_t microcode_write(struct file *, const char *, size_t, loff_t *);
static int microcode_ioctl(struct inode *, struct file *, unsigned int, unsigned long);
-
-/* internal helpers to do the work */
static int do_microcode_update(void);
static void do_update_one(void *);
-/*
- * Bits in microcode_status. (31 bits of room for future expansion)
- */
-#define MICROCODE_IS_OPEN 0 /* set if device is in use */
+/* read()/write()/ioctl() are serialized on this */
+DECLARE_RWSEM(microcode_rwsem);
-static unsigned long microcode_status;
-
-/* the actual array of microcode blocks, each 2048 bytes */
-static struct microcode *microcode;
-static unsigned int microcode_num;
-static char *mc_applied; /* holds an array of applied microcode blocks */
-static unsigned int mc_fsize;
+static struct microcode *microcode; /* array of 2048byte microcode blocks */
+static unsigned int microcode_num; /* number of chunks in microcode */
+static char *mc_applied; /* array of applied microcode blocks */
+static unsigned int mc_fsize; /* file size of /dev/cpu/microcode */
static struct file_operations microcode_fops = {
owner: THIS_MODULE,
@@ -84,7 +80,6 @@
write: microcode_write,
ioctl: microcode_ioctl,
open: microcode_open,
- release: microcode_release,
};
static struct miscdevice microcode_dev = {
@@ -112,8 +107,7 @@
printk(KERN_ERR "microcode: failed to devfs_register()\n");
return -EINVAL;
}
- printk(KERN_INFO "P6 Microcode Update Driver v%s registered\n",
- MICROCODE_VERSION);
+ printk(KERN_INFO "P6 Microcode Update Driver v%s\n", MICROCODE_VERSION);
return 0;
}
@@ -130,29 +124,12 @@
module_init(microcode_init);
module_exit(microcode_exit);
-/*
- * We enforce only one user at a time here with open/close.
- */
-static int microcode_open(struct inode *inode, struct file *file)
+static int microcode_open(struct inode *unused1, struct file *unused2)
{
- if (!capable(CAP_SYS_RAWIO))
- return -EPERM;
-
- /* one at a time, please */
- if (test_and_set_bit(MICROCODE_IS_OPEN, µcode_status))
- return -EBUSY;
-
- return 0;
+ return capable(CAP_SYS_RAWIO) ? 0 : -EPERM;
}
-/* our specific f_op->release() method needs no locking */
-static int microcode_release(struct inode *inode, struct file *file)
-{
- clear_bit(MICROCODE_IS_OPEN, µcode_status);
- return 0;
-}
-
-/* a pointer to 'struct update_req' is passed to the IPI handler = do_update_one()
+/*
* update_req[cpu].err is set to 1 if update failed on 'cpu', 0 otherwise
* if err==0, microcode[update_req[cpu].slot] points to applied block of microcode
*/
@@ -166,9 +143,11 @@
int i, error = 0, err;
struct microcode *m;
- if (smp_call_function(do_update_one, (void *)update_req, 1, 1) != 0)
- panic("do_microcode_update(): timed out waiting for other CPUs\n");
- do_update_one((void *)update_req);
+ if (smp_call_function(do_update_one, NULL, 1, 1) != 0) {
+ printk(KERN_ERR "microcode: IPI timeout, giving up\n");
+ return -EIO;
+ }
+ do_update_one(NULL);
for (i=0; i<smp_num_cpus; i++) {
err = update_req[i].err;
@@ -181,18 +160,18 @@
return error;
}
-static void do_update_one(void *arg)
+static void do_update_one(void *unused)
{
int cpu_num = smp_processor_id();
struct cpuinfo_x86 *c = cpu_data + cpu_num;
- struct update_req *req = (struct update_req *)arg + cpu_num;
+ struct update_req *req = update_req + cpu_num;
unsigned int pf = 0, val[2], rev, sig;
int i,found=0;
- req->err = 1; /* be pessimistic */
+ req->err = 1; /* assume the worst */
if (c->x86_vendor != X86_VENDOR_INTEL || c->x86 < 6){
- printk(KERN_ERR "microcode: CPU%d not an Intel P6\n", cpu_num );
+ printk(KERN_ERR "microcode: CPU%d not an Intel P6\n", cpu_num);
return;
}
@@ -242,18 +221,23 @@
}
if(!found)
- printk(KERN_ERR "microcode: found no data for CPU%d (sig=%x, pflags=%d)\n", cpu_num, sig, pf);
+ printk(KERN_ERR "microcode: CPU%d no microcode found! (sig=%x, pflags=%d)\n",
+ cpu_num, sig, pf);
}
static ssize_t microcode_read(struct file *file, char *buf, size_t len, loff_t *ppos)
{
if (*ppos >= mc_fsize)
return 0;
+ down_read(µcode_rwsem);
if (*ppos + len > mc_fsize)
len = mc_fsize - *ppos;
- if (copy_to_user(buf, mc_applied + *ppos, len))
+ if (copy_to_user(buf, mc_applied + *ppos, len)) {
+ up_read(µcode_rwsem);
return -EFAULT;
+ }
*ppos += len;
+ up_read(µcode_rwsem);
return len;
}
@@ -266,27 +250,29 @@
sizeof(struct microcode));
return -EINVAL;
}
+ down_write(µcode_rwsem);
if (!mc_applied) {
mc_applied = kmalloc(smp_num_cpus*sizeof(struct microcode),
GFP_KERNEL);
if (!mc_applied) {
printk(KERN_ERR "microcode: out of memory for saved microcode\n");
+ up_write(µcode_rwsem);
return -ENOMEM;
}
- memset(mc_applied, 0, mc_fsize);
}
- lock_kernel();
microcode_num = len/sizeof(struct microcode);
microcode = vmalloc(len);
if (!microcode) {
ret = -ENOMEM;
goto out_unlock;
}
+
if (copy_from_user(microcode, buf, len)) {
ret = -EFAULT;
goto out_fsize;
}
+
if(do_microcode_update()) {
ret = -EIO;
goto out_fsize;
@@ -298,7 +284,7 @@
devfs_set_file_size(devfs_handle, mc_fsize);
vfree(microcode);
out_unlock:
- unlock_kernel();
+ up_write(µcode_rwsem);
return ret;
}
@@ -307,23 +293,22 @@
{
switch(cmd) {
case MICROCODE_IOCFREE:
+ down_write(µcode_rwsem);
if (mc_applied) {
devfs_set_file_size(devfs_handle, 0);
- memset(mc_applied, 0, mc_fsize);
kfree(mc_applied);
mc_applied = NULL;
- printk(KERN_WARNING
- "microcode: freed %d bytes\n", mc_fsize);
+ printk(KERN_INFO "microcode: freed %d bytes\n", mc_fsize);
mc_fsize = 0;
+ up_write(µcode_rwsem);
return 0;
}
+ up_write(µcode_rwsem);
return -ENODATA;
default:
- printk(KERN_ERR "microcode: unknown ioctl cmd=%d\n",
- cmd);
+ printk(KERN_ERR "microcode: unknown ioctl cmd=%d\n", cmd);
return -EINVAL;
}
- /* NOT REACHED */
return -EINVAL;
}
-
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