On 7/29/19 8:50 PM, Mark Balantzyan wrote:
This patch rewrites the pc87413_wdt driver to use the watchdog subsystem. In
doing so, it also addresses a potential race condition owing from the
swc_base_addr variable being used before being set.
Signed-off-by: Mark Balantzyan <mbalant3@xxxxxxxxx>
"Revision of ..." is an odd subject line. Also, please start the subject line with
"watchdog: pc87413: ".
---
drivers/watchdog/Kconfig | 1 +
drivers/watchdog/pc87413_wdt.c | 294 +++++----------------------------
2 files changed, 39 insertions(+), 256 deletions(-)
diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index 9af07fd9..84a7326d 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -1166,6 +1166,7 @@ config SCx200_WDT
config PC87413_WDT
tristate "NS PC87413 watchdog"
+ select WATCHDOG_CORE
depends on X86
---help---
This is the driver for the hardware watchdog on the PC87413 chipset
diff --git a/drivers/watchdog/pc87413_wdt.c b/drivers/watchdog/pc87413_wdt.c
index 06a892e3..d1d32771 100644
--- a/drivers/watchdog/pc87413_wdt.c
+++ b/drivers/watchdog/pc87413_wdt.c
@@ -22,12 +22,10 @@
#include <linux/module.h>
#include <linux/types.h>
-#include <linux/miscdevice.h>
#include <linux/watchdog.h>
#include <linux/ioport.h>
#include <linux/delay.h>
Is this used anywhere ?
#include <linux/notifier.h>
-#include <linux/fs.h>
#include <linux/reboot.h>
notifier.h and reboot.h should not be needed if the code is changed
to use watchdog_stop_on_reboot().
#include <linux/init.h>
#include <linux/spinlock.h>
No longer needed.
@@ -65,7 +63,6 @@ static char expect_close; /* is the close expected? */
static DEFINE_SPINLOCK(io_lock); /* to guard us from io races */
No longer needed.
-static bool nowayout = WATCHDOG_NOWAYOUT;
/* -- Low level function ----------------------------------------*/
@@ -216,41 +213,32 @@ static inline void pc87413_disable_sw_wd_trg(void)
/* -- Higher level functions ------------------------------------*/
-/* Enable the watchdog */
+/* Enable/start the watchdog */
-static void pc87413_enable(void)
+static void pc87413_start(void)
I am quite sure you still see a warning here, or rather where the function is referenced.
{
- spin_lock(&io_lock);
-
pc87413_swc_bank3();
pc87413_programm_wdto(timeout);
pc87413_enable_wden();
pc87413_enable_sw_wd_tren();
pc87413_enable_sw_wd_trg();
- spin_unlock(&io_lock);
}
-/* Disable the watchdog */
+/* Disable/stop the watchdog */
-static void pc87413_disable(void)
+static void pc87413_stop(void)
Same here.
{
- spin_lock(&io_lock);
-
pc87413_swc_bank3();
pc87413_disable_sw_wd_tren();
pc87413_disable_sw_wd_trg();
pc87413_programm_wdto(0);
-
- spin_unlock(&io_lock);
}
-/* Refresh the watchdog */
+/* Refresh/keepalive the watchdog */
-static void pc87413_refresh(void)
+static void pc87413_keepalive(struct watchdog_device *wdd)
{
- spin_lock(&io_lock);
-
pc87413_swc_bank3();
pc87413_disable_sw_wd_tren();
pc87413_disable_sw_wd_trg();
@@ -258,195 +246,11 @@ static void pc87413_refresh(void)
pc87413_enable_wden();
pc87413_enable_sw_wd_tren();
pc87413_enable_sw_wd_trg();
-
- spin_unlock(&io_lock);
-}
-
-/* -- File operations -------------------------------------------*/
-
-/**
- * pc87413_open:
- * @inode: inode of device
- * @file: file handle to device
- *
- */
-
-static int pc87413_open(struct inode *inode, struct file *file)
-{
- /* /dev/watchdog can only be opened once */
-
- if (test_and_set_bit(0, &timer_enabled))
- return -EBUSY;
-
- if (nowayout)
- __module_get(THIS_MODULE);
-
- /* Reload and activate timer */
- pc87413_refresh();
-
- pr_info("Watchdog enabled. Timeout set to %d minute(s).\n", timeout);
-
- return nonseekable_open(inode, file);
-}
-
-/**
- * pc87413_release:
- * @inode: inode to board
- * @file: file handle to board
- *
- * The watchdog has a configurable API. There is a religious dispute
- * between people who want their watchdog to be able to shut down and
- * those who want to be sure if the watchdog manager dies the machine
- * reboots. In the former case we disable the counters, in the latter
- * case you have to open it again very soon.
- */
-
-static int pc87413_release(struct inode *inode, struct file *file)
-{
- /* Shut off the timer. */
-
- if (expect_close == 42) {
- pc87413_disable();
- pr_info("Watchdog disabled, sleeping again...\n");
- } else {
- pr_crit("Unexpected close, not stopping watchdog!\n");
- pc87413_refresh();
- }
- clear_bit(0, &timer_enabled);
- expect_close = 0;
return 0;
}
-/**
- * pc87413_status:
- *
- * return, if the watchdog is enabled (timeout is set...)
- */
-
-
-static int pc87413_status(void)
-{
- return 0; /* currently not supported */
-}
-
-/**
- * pc87413_write:
- * @file: file handle to the watchdog
- * @data: data buffer to write
- * @len: length in bytes
- * @ppos: pointer to the position to write. No seeks allowed
- *
- * A write to a watchdog device is defined as a keepalive signal. Any
- * write of data will do, as we we don't define content meaning.
- */
-
-static ssize_t pc87413_write(struct file *file, const char __user *data,
- size_t len, loff_t *ppos)
-{
- /* See if we got the magic character 'V' and reload the timer */
- if (len) {
- if (!nowayout) {
- size_t i;
-
- /* reset expect flag */
- expect_close = 0;
-
- /* scan to see whether or not we got the
- magic character */
- for (i = 0; i != len; i++) {
- char c;
- if (get_user(c, data + i))
- return -EFAULT;
- if (c == 'V')
- expect_close = 42;
- }
- }
-
- /* someone wrote to us, we should reload the timer */
- pc87413_refresh();
- }
- return len;
-}
-
-/**
- * pc87413_ioctl:
- * @file: file handle to the device
- * @cmd: watchdog command
- * @arg: argument pointer
- *
- * The watchdog API defines a common set of functions for all watchdogs
- * according to their available features. We only actually usefully support
- * querying capabilities and current status.
- */
-
-static long pc87413_ioctl(struct file *file, unsigned int cmd,
- unsigned long arg)
-{
- int new_timeout;
-
- union {
- struct watchdog_info __user *ident;
- int __user *i;
- } uarg;
-
- static const struct watchdog_info ident = {
- .options = WDIOF_KEEPALIVEPING |
- WDIOF_SETTIMEOUT |
- WDIOF_MAGICCLOSE,
- .firmware_version = 1,
- .identity = "PC87413(HF/F) watchdog",
- };
-
- uarg.i = (int __user *)arg;
-
- switch (cmd) {
- case WDIOC_GETSUPPORT:
- return copy_to_user(uarg.ident, &ident,
- sizeof(ident)) ? -EFAULT : 0;
- case WDIOC_GETSTATUS:
- return put_user(pc87413_status(), uarg.i);
- case WDIOC_GETBOOTSTATUS:
- return put_user(0, uarg.i);
- case WDIOC_SETOPTIONS:
- {
- int options, retval = -EINVAL;
- if (get_user(options, uarg.i))
- return -EFAULT;
- if (options & WDIOS_DISABLECARD) {
- pc87413_disable();
- retval = 0;
- }
- if (options & WDIOS_ENABLECARD) {
- pc87413_enable();
- retval = 0;
- }
- return retval;
- }
- case WDIOC_KEEPALIVE:
- pc87413_refresh();
-#ifdef DEBUG
- pr_info(DPFX "keepalive\n");
-#endif
- return 0;
- case WDIOC_SETTIMEOUT:
- if (get_user(new_timeout, uarg.i))
- return -EFAULT;
- /* the API states this is given in secs */
- new_timeout /= 60;
- if (new_timeout < 0 || new_timeout > MAX_TIMEOUT)
- return -EINVAL;
- timeout = new_timeout;
- pc87413_refresh();
- /* fall through and return the new timeout... */
- case WDIOC_GETTIMEOUT:
- new_timeout = timeout * 60;
- return put_user(new_timeout, uarg.i);
- default:
- return -ENOTTY;
- }
-}
-/* -- Notifier funtions -----------------------------------------*/
+/* -- Notifier functions -----------------------------------------*/
/**
* notify_sys:
@@ -460,37 +264,43 @@ static long pc87413_ioctl(struct file *file, unsigned int cmd,
* trust me - if it happens it does suck.
*/
-static int pc87413_notify_sys(struct notifier_block *this,
- unsigned long code,
- void *unused)
+
+/* -- Module's structures ---------------------------------------*/
+
+
+static int watchdog_restart_notifier(struct notifier_block *nb,
+ unsigned long code, void *data)
{
- if (code == SYS_DOWN || code == SYS_HALT)
- /* Turn the card off */
- pc87413_disable();
+ struct watchdog_device *wdd = container_of(nb, struct watchdog_device,
+ reboot_nb);
+
+ if (code == SYS_DOWN || code == SYS_HALT) {
+ int ret;
+
+ ret = wdd->ops->stop(wdd);
+ if (ret)
+ return NOTIFY_BAD;
+ }
+
return NOTIFY_DONE;
}
As mentioned, please drop the notifier function and call watchdog_stop_on_reboot()
prior to registering the watchdog.
-/* -- Module's structures ---------------------------------------*/
-static const struct file_operations pc87413_fops = {
- .owner = THIS_MODULE,
- .llseek = no_llseek,
- .write = pc87413_write,
- .unlocked_ioctl = pc87413_ioctl,
- .open = pc87413_open,
- .release = pc87413_release,
-};
-static struct notifier_block pc87413_notifier = {
- .notifier_call = pc87413_notify_sys,
+static struct watchdog_ops pc87413wdt_ops = {
+ .owner = THIS_MODULE,
+ .start = pc87413_start,
+ .stop = pc87413_stop,
+ .ping = pc87413_keepalive,
I don't immediately see how timeouts are now handled, and I am not sure
if they are handled correctly, especially with the removed
/* the API states this is given in secs */
new_timeout /= 60;
above, and the datasheet says that timeouts are in multiples of minutes.
This means that a set_)timeout function will be needed to calculate and
set the correct timeout values.
+ .restart = watchdog_restart_notifier,
Bad alignment
};
-static struct miscdevice pc87413_miscdev = {
- .minor = WATCHDOG_MINOR,
- .name = "watchdog",
- .fops = &pc87413_fops,
+static struct watchdog_device pc87413wdt_wdd = {
+ .ops = &pc87413wdt_ops,
+ .status = WATCHDOG_NOWAYOUT_INIT_STATUS,
};
+
/* -- Module init functions -------------------------------------*/
/**
@@ -498,7 +308,6 @@ static struct miscdevice pc87413_miscdev = {
*
* Set up the WDT watchdog board. All we have to do is grab the
* resources we require and bitch if anyone beat us to them.
- * The open() function will actually kick the board off.
*/
static int __init pc87413_init(void)
@@ -511,16 +320,7 @@ static int __init pc87413_init(void)
if (!request_muxed_region(io, 2, MODNAME))
return -EBUSY;
- ret = register_reboot_notifier(&pc87413_notifier);
- if (ret != 0)
- pr_err("cannot register reboot notifier (err=%d)\n", ret);
-
- ret = misc_register(&pc87413_miscdev);
- if (ret != 0) {
- pr_err("cannot register miscdev on minor=%d (err=%d)\n",
- WATCHDOG_MINOR, ret);
- goto reboot_unreg;
- }
+ ret = watchdog_register_device(&pc87413wdt_wdd);
pr_info("initialized. timeout=%d min\n", timeout);
pc87413_select_wdt_out();
@@ -533,17 +333,12 @@ static int __init pc87413_init(void)
goto misc_unreg;
}
- pc87413_enable();
-
release_region(io, 2);
+ pc87413_keepalive(&pc87413wdt_wdd);
Not needed: The watchdog is not (or should not be) running.
return 0;
misc_unreg:
Wrong label name.
- misc_deregister(&pc87413_miscdev);
-reboot_unreg:
- unregister_reboot_notifier(&pc87413_notifier);
- release_region(io, 2);
- return ret;
+ watchdog_unregister_device(&pc87413wdt_wdd);
I am getting a bit lost here, but it seems to me this is called if
watchdog registration failed. The cleanup is wrong. You still need
to call release_region(), you don't need to unregister the watchdog,
and you still need to return ret.
}
/**
@@ -558,14 +353,7 @@ reboot_unreg:
static void __exit pc87413_exit(void)
{
- /* Stop the timer before we leave */
- if (!nowayout) {
- pc87413_disable();
- pr_info("Watchdog disabled\n");
- }
-
- misc_deregister(&pc87413_miscdev);
- unregister_reboot_notifier(&pc87413_notifier);
+ watchdog_unregister_device(&pc87413wdt_wdd);
release_region(swc_base_addr, 0x20);
pr_info("watchdog component driver removed\n");
@@ -587,9 +375,3 @@ module_param(timeout, int, 0);
MODULE_PARM_DESC(timeout,
"Watchdog timeout in minutes (default="
__MODULE_STRING(DEFAULT_TIMEOUT) ").");
-
-module_param(nowayout, bool, 0);
-MODULE_PARM_DESC(nowayout,
- "Watchdog cannot be stopped once started (default="
- __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
-
Again, why drop this module parameter ?
