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Use stop_machine_run in the Intel RNG driver 

Replace call_smp_function with stop_machine_run in the Intel RNG driver.

CPU A has done read_lock(&lock)
CPU B has done write_lock_irq(&lock) and is waiting for A to release the lock.

A third CPU calls call_smp_function and issues the IPI.  CPU A takes CPU
C's IPI.  CPU B is waiting with interrupts disabled and does not see the
IPI.  CPU C is stuck waiting for CPU B to respond to the IPI.

Deadlock.

The solution is to use stop_machine_run instead of call_smp_function
(call_smp_function should not be called in situations where the CPUs may be
suspended).

[haruo.tomita@toshiba.co.jp: fix a typo in mod_init()]
[haruo.tomita@toshiba.co.jp: fix memory leak]
Signed-off-by: Prarit Bhargava <prarit@redhat.com>
Cc: Jan Beulich <jbeulich@novell.com>
Cc: "Tomita, Haruo" <haruo.tomita@toshiba.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Prarit Bhargava 2007-05-08 00:25:08 -07:00 committed by Linus Torvalds
parent 616883df78
commit ee527cd3a2
2 changed files with 129 additions and 102 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

223
drivers/char/hw_random/intel-rng.c
View File

@ -24,10 +24,11 @@
* warranty of any kind, whether express or implied.
*/
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/pci.h>
#include <linux/hw_random.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/pci.h>
#include <linux/stop_machine.h>
#include <asm/io.h>
@ -217,30 +218,117 @@ static struct hwrng intel_rng = {
.data_read = intel_rng_data_read,
};
struct intel_rng_hw {
struct pci_dev *dev;
void __iomem *mem;
u8 bios_cntl_off;
u8 bios_cntl_val;
u8 fwh_dec_en1_off;
u8 fwh_dec_en1_val;
};
#ifdef CONFIG_SMP
static char __initdata waitflag;
static void __init intel_init_wait(void *unused)
static int __init intel_rng_hw_init(void *_intel_rng_hw)
{
while (waitflag)
cpu_relax();
struct intel_rng_hw *intel_rng_hw = _intel_rng_hw;
u8 mfc, dvc;
/* interrupts disabled in stop_machine_run call */
if (!(intel_rng_hw->fwh_dec_en1_val & FWH_F8_EN_MASK))
pci_write_config_byte(intel_rng_hw->dev,
intel_rng_hw->fwh_dec_en1_off,
intel_rng_hw->fwh_dec_en1_val |
FWH_F8_EN_MASK);
if (!(intel_rng_hw->bios_cntl_val & BIOS_CNTL_WRITE_ENABLE_MASK))
pci_write_config_byte(intel_rng_hw->dev,
intel_rng_hw->bios_cntl_off,
intel_rng_hw->bios_cntl_val |
BIOS_CNTL_WRITE_ENABLE_MASK);
writeb(INTEL_FWH_RESET_CMD, intel_rng_hw->mem);
writeb(INTEL_FWH_READ_ID_CMD, intel_rng_hw->mem);
mfc = readb(intel_rng_hw->mem + INTEL_FWH_MANUFACTURER_CODE_ADDRESS);
dvc = readb(intel_rng_hw->mem + INTEL_FWH_DEVICE_CODE_ADDRESS);
writeb(INTEL_FWH_RESET_CMD, intel_rng_hw->mem);
if (!(intel_rng_hw->bios_cntl_val &
(BIOS_CNTL_LOCK_ENABLE_MASK|BIOS_CNTL_WRITE_ENABLE_MASK)))
pci_write_config_byte(intel_rng_hw->dev,
intel_rng_hw->bios_cntl_off,
intel_rng_hw->bios_cntl_val);
if (!(intel_rng_hw->fwh_dec_en1_val & FWH_F8_EN_MASK))
pci_write_config_byte(intel_rng_hw->dev,
intel_rng_hw->fwh_dec_en1_off,
intel_rng_hw->fwh_dec_en1_val);
if (mfc != INTEL_FWH_MANUFACTURER_CODE ||
(dvc != INTEL_FWH_DEVICE_CODE_8M &&
dvc != INTEL_FWH_DEVICE_CODE_4M)) {
printk(KERN_ERR PFX "FWH not detected\n");
return -ENODEV;
}
return 0;
}
#endif
static int __init intel_init_hw_struct(struct intel_rng_hw *intel_rng_hw,
struct pci_dev *dev)
{
intel_rng_hw->bios_cntl_val = 0xff;
intel_rng_hw->fwh_dec_en1_val = 0xff;
intel_rng_hw->dev = dev;
/* Check for Intel 82802 */
if (dev->device < 0x2640) {
intel_rng_hw->fwh_dec_en1_off = FWH_DEC_EN1_REG_OLD;
intel_rng_hw->bios_cntl_off = BIOS_CNTL_REG_OLD;
} else {
intel_rng_hw->fwh_dec_en1_off = FWH_DEC_EN1_REG_NEW;
intel_rng_hw->bios_cntl_off = BIOS_CNTL_REG_NEW;
}
pci_read_config_byte(dev, intel_rng_hw->fwh_dec_en1_off,
&intel_rng_hw->fwh_dec_en1_val);
pci_read_config_byte(dev, intel_rng_hw->bios_cntl_off,
&intel_rng_hw->bios_cntl_val);
if ((intel_rng_hw->bios_cntl_val &
(BIOS_CNTL_LOCK_ENABLE_MASK|BIOS_CNTL_WRITE_ENABLE_MASK))
== BIOS_CNTL_LOCK_ENABLE_MASK) {
static __initdata /*const*/ char warning[] =
KERN_WARNING PFX "Firmware space is locked read-only. "
KERN_WARNING PFX "If you can't or\n don't want to "
KERN_WARNING PFX "disable this in firmware setup, and "
KERN_WARNING PFX "if\n you are certain that your "
KERN_WARNING PFX "system has a functional\n RNG, try"
KERN_WARNING PFX "using the 'no_fwh_detect' option.\n";
if (no_fwh_detect)
return -ENODEV;
printk(warning);
return -EBUSY;
}
intel_rng_hw->mem = ioremap_nocache(INTEL_FWH_ADDR, INTEL_FWH_ADDR_LEN);
if (intel_rng_hw->mem == NULL)
return -EBUSY;
return 0;
}
static int __init mod_init(void)
{
int err = -ENODEV;
unsigned i;
int i;
struct pci_dev *dev = NULL;
void __iomem *mem;
unsigned long flags;
u8 bios_cntl_off, fwh_dec_en1_off;
u8 bios_cntl_val = 0xff, fwh_dec_en1_val = 0xff;
u8 hw_status, mfc, dvc;
void __iomem *mem = mem;
u8 hw_status;
struct intel_rng_hw *intel_rng_hw;
for (i = 0; !dev && pci_tbl[i].vendor; ++i)
dev = pci_get_device(pci_tbl[i].vendor, pci_tbl[i].device, NULL);
dev = pci_get_device(pci_tbl[i].vendor, pci_tbl[i].device,
NULL);
if (!dev)
goto out; /* Device not found. */
@ -250,39 +338,18 @@ static int __init mod_init(void)
goto fwh_done;
}
/* Check for Intel 82802 */
if (dev->device < 0x2640) {
fwh_dec_en1_off = FWH_DEC_EN1_REG_OLD;
bios_cntl_off = BIOS_CNTL_REG_OLD;
} else {
fwh_dec_en1_off = FWH_DEC_EN1_REG_NEW;
bios_cntl_off = BIOS_CNTL_REG_NEW;
}
pci_read_config_byte(dev, fwh_dec_en1_off, &fwh_dec_en1_val);
pci_read_config_byte(dev, bios_cntl_off, &bios_cntl_val);
if ((bios_cntl_val &
(BIOS_CNTL_LOCK_ENABLE_MASK|BIOS_CNTL_WRITE_ENABLE_MASK))
== BIOS_CNTL_LOCK_ENABLE_MASK) {
static __initdata /*const*/ char warning[] =
KERN_WARNING PFX "Firmware space is locked read-only. If you can't or\n"
KERN_WARNING PFX "don't want to disable this in firmware setup, and if\n"
KERN_WARNING PFX "you are certain that your system has a functional\n"
KERN_WARNING PFX "RNG, try using the 'no_fwh_detect' option.\n";
intel_rng_hw = kmalloc(sizeof(*intel_rng_hw), GFP_KERNEL);
if (!intel_rng_hw) {
pci_dev_put(dev);
if (no_fwh_detect)
goto fwh_done;
printk(warning);
err = -EBUSY;
goto out;
}
mem = ioremap_nocache(INTEL_FWH_ADDR, INTEL_FWH_ADDR_LEN);
if (mem == NULL) {
err = intel_init_hw_struct(intel_rng_hw, dev);
if (err) {
pci_dev_put(dev);
err = -EBUSY;
kfree(intel_rng_hw);
if (err == -ENODEV)
goto fwh_done;
goto out;
}
@ -290,59 +357,18 @@ static int __init mod_init(void)
* Since the BIOS code/data is going to disappear from its normal
* location with the Read ID command, all activity on the system
* must be stopped until the state is back to normal.
*
* Use stop_machine_run because IPIs can be blocked by disabling
* interrupts.
*/
#ifdef CONFIG_SMP
set_mb(waitflag, 1);
if (smp_call_function(intel_init_wait, NULL, 1, 0) != 0) {
set_mb(waitflag, 0);
pci_dev_put(dev);
printk(KERN_ERR PFX "cannot run on all processors\n");
err = -EAGAIN;
goto err_unmap;
}
#endif
local_irq_save(flags);
if (!(fwh_dec_en1_val & FWH_F8_EN_MASK))
pci_write_config_byte(dev,
fwh_dec_en1_off,
fwh_dec_en1_val | FWH_F8_EN_MASK);
if (!(bios_cntl_val & BIOS_CNTL_WRITE_ENABLE_MASK))
pci_write_config_byte(dev,
bios_cntl_off,
bios_cntl_val | BIOS_CNTL_WRITE_ENABLE_MASK);
writeb(INTEL_FWH_RESET_CMD, mem);
writeb(INTEL_FWH_READ_ID_CMD, mem);
mfc = readb(mem + INTEL_FWH_MANUFACTURER_CODE_ADDRESS);
dvc = readb(mem + INTEL_FWH_DEVICE_CODE_ADDRESS);
writeb(INTEL_FWH_RESET_CMD, mem);
if (!(bios_cntl_val &
(BIOS_CNTL_LOCK_ENABLE_MASK|BIOS_CNTL_WRITE_ENABLE_MASK)))
pci_write_config_byte(dev, bios_cntl_off, bios_cntl_val);
if (!(fwh_dec_en1_val & FWH_F8_EN_MASK))
pci_write_config_byte(dev, fwh_dec_en1_off, fwh_dec_en1_val);
local_irq_restore(flags);
#ifdef CONFIG_SMP
/* Tell other CPUs to resume. */
set_mb(waitflag, 0);
#endif
iounmap(mem);
err = stop_machine_run(intel_rng_hw_init, intel_rng_hw, NR_CPUS);
pci_dev_put(dev);
if (mfc != INTEL_FWH_MANUFACTURER_CODE ||
(dvc != INTEL_FWH_DEVICE_CODE_8M &&
dvc != INTEL_FWH_DEVICE_CODE_4M)) {
printk(KERN_ERR PFX "FWH not detected\n");
err = -ENODEV;
iounmap(intel_rng_hw->mem);
kfree(intel_rng_hw);
if (err)
goto out;
}
fwh_done:
err = -ENOMEM;
mem = ioremap(INTEL_RNG_ADDR, INTEL_RNG_ADDR_LEN);
if (!mem)
@ -352,22 +378,21 @@ fwh_done:
/* Check for Random Number Generator */
err = -ENODEV;
hw_status = hwstatus_get(mem);
if ((hw_status & INTEL_RNG_PRESENT) == 0)
goto err_unmap;
if ((hw_status & INTEL_RNG_PRESENT) == 0) {
iounmap(mem);
goto out;
}
printk(KERN_INFO "Intel 82802 RNG detected\n");
err = hwrng_register(&intel_rng);
if (err) {
printk(KERN_ERR PFX "RNG registering failed (%d)\n",
err);
goto err_unmap;
iounmap(mem);
}
out:
return err;
err_unmap:
iounmap(mem);
goto out;
}
static void __exit mod_exit(void)

8
kernel/stop_machine.c
View File

@ -1,11 +1,12 @@
/* Copyright 2005 Rusty Russell rusty@rustcorp.com.au IBM Corporation.
* GPL v2 and any later version.
*/
#include <linux/stop_machine.h>
#include <linux/kthread.h>
#include <linux/sched.h>
#include <linux/cpu.h>
#include <linux/err.h>
#include <linux/kthread.h>
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/stop_machine.h>
#include <linux/syscalls.h>
#include <asm/atomic.h>
#include <asm/semaphore.h>
@ -208,3 +209,4 @@ int stop_machine_run(int (*fn)(void *), void *data, unsigned int cpu)
return ret;
}
EXPORT_SYMBOL_GPL(stop_machine_run);