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Date: Mon, 29 Jul 2019 14:59:38 -0700
From: Guenter Roeck <linux@...ck-us.net>
To: Mark Balantzyan <mbalant3@...il.com>
Cc: wim@...ux-watchdog.org, linux-watchdog@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH] watchdog device drivers:pc87413_wdt: Rewriting of
pc87413_wdt driver to utilize common watchdog interface
On Mon, Jul 29, 2019 at 02:20:16PM -0700, Mark Balantzyan wrote:
> There is a potential for the variable swc_base_addr in the call chain of the
> driver initialization function (init) to be used before initialization. This
> brought up the need for, by rewriting the driver to use the common watchdog
> interface, ensuring to have all resources in place. This patch addresses this
> need by rewriting into common watchdog interface utilization for the driver.
>
> Signed-off-by: Mark Balantzyan <mbalant3@...il.com>
>
This patch shows up as corrupted if I try to apply it.
> ---
> drivers/media/pci/tw686x/Kconfig | 1 +
> drivers/watchdog/pc87413_wdt.c | 92 +++++++++++++++-----------------
> 2 files changed, 45 insertions(+), 48 deletions(-)
>
> diff --git a/drivers/media/pci/tw686x/Kconfig
> b/drivers/media/pci/tw686x/Kconfig
> index da8bfee7..079d7464 100644
> --- a/drivers/media/pci/tw686x/Kconfig
> +++ b/drivers/media/pci/tw686x/Kconfig
> @@ -5,6 +5,7 @@ config VIDEO_TW686X
> select VIDEOBUF2_DMA_CONTIG
> select VIDEOBUF2_DMA_SG
> select SND_PCM
> + select WATCHDOG_CORE
> help
> Support for Intersil/Techwell TW686x-based frame grabber cards.
>
> diff --git a/drivers/watchdog/pc87413_wdt.c b/drivers/watchdog/pc87413_wdt.c
> index 06a892e3..4c330ee5 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>
> #include <linux/notifier.h>
> -#include <linux/fs.h>
> #include <linux/reboot.h>
> #include <linux/init.h>
> #include <linux/spinlock.h>
> @@ -65,7 +63,6 @@ static char expect_close; /* is the close expected? */
>
> static DEFINE_SPINLOCK(io_lock); /* to guard us from io races */
>
> -static bool nowayout = WATCHDOG_NOWAYOUT;
>
> /* -- Low level function ----------------------------------------*/
>
> @@ -216,9 +213,9 @@ 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)
> {
> spin_lock(&io_lock);
>
> @@ -231,9 +228,9 @@ static void pc87413_enable(void)
> spin_unlock(&io_lock);
> }
>
> -/* Disable the watchdog */
> +/* Disable/stop the watchdog */
>
> -static void pc87413_disable(void)
> +static void pc87413_stop(void)
> {
> spin_lock(&io_lock);
Locking is handled by the watchdog core. Local locking is no
longer needed.
>
> @@ -245,9 +242,9 @@ static void pc87413_disable(void)
> 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);
>
> @@ -260,6 +257,8 @@ static void pc87413_refresh(void)
> pc87413_enable_sw_wd_trg();
>
> spin_unlock(&io_lock);
> +
> + return 0;
> }
>
> /* -- File operations -------------------------------------------*/
> @@ -278,9 +277,6 @@ static int pc87413_open(struct inode *inode, struct file
> *file)
WHy is this function still there ?
> if (test_and_set_bit(0, &timer_enabled))
> return -EBUSY;
>
> - if (nowayout)
> - __module_get(THIS_MODULE);
> -
> /* Reload and activate timer */
> pc87413_refresh();
>
> @@ -331,7 +327,6 @@ static int pc87413_status(void)
>
> /**
> * 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
> @@ -345,26 +340,25 @@ static ssize_t pc87413_write(struct file *file, const
> char __user *data,
> {
This function is no longer needed or used.
> /* 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;
> - }
> + 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();
> - }
> + pc87413_refresh();
> +
> return len;
> }
>
> @@ -417,7 +411,7 @@ static long pc87413_ioctl(struct file *file, unsigned int
> cmd,
Another function that is no longer needed. And the above looks corrupted.
> retval = 0;
> }
> if (options & WDIOS_ENABLECARD) {
> - pc87413_enable();
> + pc87413_start();
> retval = 0;
> }
> return retval;
> @@ -466,31 +460,32 @@ static int pc87413_notify_sys(struct notifier_block
> *this,
Drivers using the watchdog core should use the watchdog core's
restart notifier.
> {
> if (code == SYS_DOWN || code == SYS_HALT)
> /* Turn the card off */
> - pc87413_disable();
> + pc87413_stop();
> return NOTIFY_DONE;
> }
>
> /* -- 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 = {
> +static struct notifier_block pc87413wdt_notifier = {
> .notifier_call = pc87413_notify_sys,
> };
>
> -static struct miscdevice pc87413_miscdev = {
> - .minor = WATCHDOG_MINOR,
> - .name = "watchdog",
> - .fops = &pc87413_fops,
> +static struct watchdog_ops pc87413wdt_ops = {
> + .owner = THIS_MODULE,
> + .start = pc87413wdt_start,
> + .stop = pc87413wdt_stop,
> + .ping = pc87413wdt_keepalive,
> + .set_timeout = pc87413wdt_set_heartbeat,
> +};
> +
> +static struct watchdog_device pc87413wdt_wdd = {
> + .info = &pc87413wdt_ident,
> + .ops = &pc87413wdt_ops,
> + .status = WATCHDOG_NOWAYOUT_INIT_STATUS
> };
>
> +
> /* -- Module init functions -------------------------------------*/
>
> /**
> @@ -515,7 +510,7 @@ static int __init pc87413_init(void)
> if (ret != 0)
> pr_err("cannot register reboot notifier (err=%d)\n", ret);
>
> - ret = misc_register(&pc87413_miscdev);
> + ret = watchdog_register_device(&pc87413wdt_wdd);
> if (ret != 0) {
> pr_err("cannot register miscdev on minor=%d (err=%d)\n",
> WATCHDOG_MINOR, ret);
> @@ -533,13 +528,14 @@ static int __init pc87413_init(void)
> goto misc_unreg;
> }
>
> - pc87413_enable();
> + pc87413_start();
>
Hmm ... I don't think starting the watchdog in the probe function is a good
idea. One reason to believe that no one is actually using it.
> release_region(io, 2);
> + pc87413_keepalive(&pc87413wdt_wdd);
> return 0;
>
> misc_unreg:
> - misc_deregister(&pc87413_miscdev);
> + watchdog_unregister_device(&pc87413wdt_wdd)
> reboot_unreg:
> unregister_reboot_notifier(&pc87413_notifier);
> release_region(io, 2);
Are you sure you even compiled this file ? It still calls
misc_deregister() in the exit function, but miscdevice.h is
no longer included. And the now unnecessary but still present
functions should at the very least trigger a build warning.
Overall, I don't think you have this hardware. If you do, please provide
logs showing that the new driver is working. Otherwise, I really think it
would be better to leave it alone.
Thanks,
Guenter
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