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Message-Id: <20080501145137.a5af389c.akpm@linux-foundation.org>
Date: Thu, 1 May 2008 14:51:37 -0700
From: Andrew Morton <akpm@...ux-foundation.org>
To: Chen Gong <g.chen@...escale.com>
Cc: linuxppc-dev@...abs.org, wim@...ana.be,
linux-kernel@...r.kernel.org, g.chen@...escale.com
Subject: Re: [PATCH] Watchdog on MPC85xx SMP system
On Tue, 29 Apr 2008 16:42:05 +0800
Chen Gong <g.chen@...escale.com> wrote:
> On Book-E SMP systems each core has its own private watchdog.
> If only one watchdog is enabled, when the core that doesn't
> enable the watchdog is hung, system can't reset because no
> watchdog is running on it. That's bad. It means we must
> enable watchdogs on both cores.
>
> We can use smp_call_function() to send appropriate messages to
> all the other cores to enable and update the watchdog.
>
> Signed-off-by: Chen Gong <g.chen@...escale.com>
> ---
> Now Tested on MPC8572DS platform.
>
> drivers/watchdog/booke_wdt.c | 31 +++++++++++++++++++++++--------
> 1 files changed, 23 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/watchdog/booke_wdt.c b/drivers/watchdog/booke_wdt.c
> index d362f5b..8a4e7f0 100644
> --- a/drivers/watchdog/booke_wdt.c
> +++ b/drivers/watchdog/booke_wdt.c
> @@ -1,12 +1,12 @@
> /*
> - * drivers/char/watchdog/booke_wdt.c
> + * drivers/watchdog/booke_wdt.c
> *
> * Watchdog timer for PowerPC Book-E systems
> *
> * Author: Matthew McClintock
> * Maintainer: Kumar Gala <galak@...nel.crashing.org>
> *
> - * Copyright 2005 Freescale Semiconductor Inc.
> + * Copyright 2005, 2008 Freescale Semiconductor Inc.
> *
> * This program is free software; you can redistribute it and/or modify it
> * under the terms of the GNU General Public License as published by the
> @@ -16,6 +16,7 @@
>
> #include <linux/module.h>
> #include <linux/fs.h>
> +#include <linux/smp.h>
> #include <linux/miscdevice.h>
> #include <linux/notifier.h>
> #include <linux/watchdog.h>
> @@ -47,23 +48,31 @@ u32 booke_wdt_period = WDT_PERIOD_DEFAULT;
> #define WDTP(x) (TCR_WP(x))
> #endif
>
> +static DEFINE_SPINLOCK(booke_wdt_lock);
> +
> +static void __booke_wdt_ping(void *data)
> +{
> + mtspr(SPRN_TSR, TSR_ENW|TSR_WIS);
> +}
> +
> /*
> * booke_wdt_ping:
> */
> static __inline__ void booke_wdt_ping(void)
> {
> - mtspr(SPRN_TSR, TSR_ENW|TSR_WIS);
> + smp_call_function(__booke_wdt_ping, NULL, 0, 0);
> + __booke_wdt_ping(NULL);
> }
>
> /*
> - * booke_wdt_enable:
> + * __booke_wdt_enable:
> */
> -static __inline__ void booke_wdt_enable(void)
> +static inline void __booke_wdt_enable(void *data)
> {
> u32 val;
>
> /* clear status before enabling watchdog */
> - booke_wdt_ping();
> + __booke_wdt_ping(NULL);
> val = mfspr(SPRN_TCR);
> val |= (TCR_WIE|TCR_WRC(WRC_CHIP)|WDTP(booke_wdt_period));
>
> @@ -137,12 +146,15 @@ static int booke_wdt_ioctl (struct inode *inode, struct file *file,
> */
> static int booke_wdt_open (struct inode *inode, struct file *file)
> {
> + spin_lock(&booke_wdt_lock);
> if (booke_wdt_enabled == 0) {
> booke_wdt_enabled = 1;
> - booke_wdt_enable();
> + __booke_wdt_enable(NULL);
> + smp_call_function(__booke_wdt_enable, NULL, 0, 0);
It's nonsensical to call an inlined function via smp_call_function(). What
we're asking the compiler to do here is to generate both an out-of-line
copy and an inlined copy.
Also, the above is an open-coded version of on_each_cpu().
so... something like the below should tidy that up, along with numerous
other things. Can you please check it over?
diff -puN drivers/watchdog/booke_wdt.c~watchdog-fix-booke_wdtc-on-mpc85xx-smp-system-fix drivers/watchdog/booke_wdt.c
--- a/drivers/watchdog/booke_wdt.c~watchdog-fix-booke_wdtc-on-mpc85xx-smp-system-fix
+++ a/drivers/watchdog/booke_wdt.c
@@ -1,6 +1,4 @@
/*
- * drivers/watchdog/booke_wdt.c
- *
* Watchdog timer for PowerPC Book-E systems
*
* Author: Matthew McClintock
@@ -39,7 +37,7 @@
#define WDT_PERIOD_DEFAULT 3 /* Refer to the PPC40x and PPC4xx manuals */
#endif /* for timing information */
-u32 booke_wdt_enabled = 0;
+u32 booke_wdt_enabled;
u32 booke_wdt_period = WDT_PERIOD_DEFAULT;
#ifdef CONFIG_FSL_BOOKE
@@ -55,19 +53,12 @@ static void __booke_wdt_ping(void *data)
mtspr(SPRN_TSR, TSR_ENW|TSR_WIS);
}
-/*
- * booke_wdt_ping:
- */
-static __inline__ void booke_wdt_ping(void)
+static void booke_wdt_ping(void)
{
- smp_call_function(__booke_wdt_ping, NULL, 0, 0);
- __booke_wdt_ping(NULL);
+ on_each_cpu(__booke_wdt_ping, NULL, 0, 0);
}
-/*
- * __booke_wdt_enable:
- */
-static inline void __booke_wdt_enable(void *data)
+static void __booke_wdt_enable(void *data)
{
u32 val;
@@ -79,10 +70,7 @@ static inline void __booke_wdt_enable(vo
mtspr(SPRN_TCR, val);
}
-/*
- * booke_wdt_write:
- */
-static ssize_t booke_wdt_write (struct file *file, const char __user *buf,
+static ssize_t booke_wdt_write(struct file *file, const char __user *buf,
size_t count, loff_t *ppos)
{
booke_wdt_ping();
@@ -90,15 +78,11 @@ static ssize_t booke_wdt_write (struct f
}
static struct watchdog_info ident = {
- .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
- .firmware_version = 0,
- .identity = "PowerPC Book-E Watchdog",
+ .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
+ .identity = "PowerPC Book-E Watchdog",
};
-/*
- * booke_wdt_ioctl:
- */
-static int booke_wdt_ioctl (struct inode *inode, struct file *file,
+static int booke_wdt_ioctl(struct inode *inode, struct file *file,
unsigned int cmd, unsigned long arg)
{
u32 tmp = 0;
@@ -106,7 +90,7 @@ static int booke_wdt_ioctl (struct inode
switch (cmd) {
case WDIOC_GETSUPPORT:
- if (copy_to_user ((struct watchdog_info __user *) arg, &ident,
+ if (copy_to_user((struct watchdog_info __user *)arg, &ident,
sizeof(struct watchdog_info)))
return -EFAULT;
case WDIOC_GETSTATUS:
@@ -141,18 +125,15 @@ static int booke_wdt_ioctl (struct inode
return 0;
}
-/*
- * booke_wdt_open:
- */
-static int booke_wdt_open (struct inode *inode, struct file *file)
+
+static int booke_wdt_open(struct inode *inode, struct file *file)
{
spin_lock(&booke_wdt_lock);
if (booke_wdt_enabled == 0) {
booke_wdt_enabled = 1;
- __booke_wdt_enable(NULL);
- smp_call_function(__booke_wdt_enable, NULL, 0, 0);
- printk (KERN_INFO "PowerPC Book-E Watchdog Timer Enabled (wdt_period=%d)\n",
- booke_wdt_period);
+ on_each_cpu(__booke_wdt_enable, NULL, 0, 0);
+ printk(KERN_INFO "PowerPC Book-E Watchdog Timer Enabled "
+ "(wdt_period=%d)\n", booke_wdt_period);
}
spin_unlock(&booke_wdt_lock);
@@ -160,17 +141,17 @@ static int booke_wdt_open (struct inode
}
static const struct file_operations booke_wdt_fops = {
- .owner = THIS_MODULE,
- .llseek = no_llseek,
- .write = booke_wdt_write,
- .ioctl = booke_wdt_ioctl,
- .open = booke_wdt_open,
+ .owner = THIS_MODULE,
+ .llseek = no_llseek,
+ .write = booke_wdt_write,
+ .ioctl = booke_wdt_ioctl,
+ .open = booke_wdt_open,
};
static struct miscdevice booke_wdt_miscdev = {
- .minor = WATCHDOG_MINOR,
- .name = "watchdog",
- .fops = &booke_wdt_fops,
+ .minor = WATCHDOG_MINOR,
+ .name = "watchdog",
+ .fops = &booke_wdt_fops,
};
static void __exit booke_wdt_exit(void)
@@ -178,29 +159,25 @@ static void __exit booke_wdt_exit(void)
misc_deregister(&booke_wdt_miscdev);
}
-/*
- * booke_wdt_init:
- */
static int __init booke_wdt_init(void)
{
int ret = 0;
- printk (KERN_INFO "PowerPC Book-E Watchdog Timer Loaded\n");
+ printk(KERN_INFO "PowerPC Book-E Watchdog Timer Loaded\n");
ident.firmware_version = cur_cpu_spec->pvr_value;
ret = misc_register(&booke_wdt_miscdev);
if (ret) {
- printk (KERN_CRIT "Cannot register miscdev on minor=%d (err=%d)\n",
+ printk(KERN_CRIT "Cannot register miscdev on minor=%d: %d\n",
WATCHDOG_MINOR, ret);
return ret;
}
spin_lock(&booke_wdt_lock);
if (booke_wdt_enabled == 1) {
- printk (KERN_INFO "PowerPC Book-E Watchdog Timer Enabled (wdt_period=%d)\n",
- booke_wdt_period);
- __booke_wdt_enable(NULL);
- smp_call_function(__booke_wdt_enable, NULL, 0, 0);
+ printk (KERN_INFO "PowerPC Book-E Watchdog Timer Enabled "
+ "(wdt_period=%d)\n", booke_wdt_period);
+ on_each_cpu(__booke_wdt_enable, NULL, 0, 0);
}
spin_unlock(&booke_wdt_lock);
_
--
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