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Date: Fri, 3 Feb 2023 10:34:49 -0800
From: Guenter Roeck <linux@...ck-us.net>
To: Alexander Egorenkov <egorenar@...ux.ibm.com>,
wim@...ux-watchdog.org
Cc: linux-watchdog@...r.kernel.org, linux-kernel@...r.kernel.org,
hca@...ux.ibm.com
Subject: Re: [PATCH 3/5] watchdog: diag288_wdt: unify command buffer handling
for diag288 zvm
On 2/2/23 23:39, Alexander Egorenkov wrote:
> Simplify and de-duplicate code by introducing a common single command
> buffer allocated once at initialization. Moreover, simplify the interface
> of __diag288_vm() by accepting ASCII strings as the command parameter
> and converting it to the EBCDIC format within the function itself.
>
> Reviewed-by: Heiko Carstens <hca@...ux.ibm.com>
> Signed-off-by: Alexander Egorenkov <egorenar@...ux.ibm.com>
> ---
> drivers/watchdog/diag288_wdt.c | 55 +++++++++++++---------------------
> 1 file changed, 20 insertions(+), 35 deletions(-)
>
> diff --git a/drivers/watchdog/diag288_wdt.c b/drivers/watchdog/diag288_wdt.c
> index c8d516ced6d2..c717f47dd4c3 100644
> --- a/drivers/watchdog/diag288_wdt.c
> +++ b/drivers/watchdog/diag288_wdt.c
> @@ -69,6 +69,8 @@ MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default = C
>
> MODULE_ALIAS("vmwatchdog");
>
> +static char *cmd_buf;
> +
Personally I wound not even bother allocating this, but that is just my personal
opinion. And I guess one more static variable doesn't make much of a difference
either.
Reviewed-by: Guenter Roeck <linux@...ck-us.net>
> static int __diag288(unsigned int func, unsigned int timeout,
> unsigned long action, unsigned int len)
> {
> @@ -88,11 +90,18 @@ static int __diag288(unsigned int func, unsigned int timeout,
> return err;
> }
>
> -static int __diag288_vm(unsigned int func, unsigned int timeout,
> - char *cmd, size_t len)
> +static int __diag288_vm(unsigned int func, unsigned int timeout, char *cmd)
> {
> + ssize_t len;
> +
> + len = strscpy(cmd_buf, cmd, MAX_CMDLEN);
> + if (len < 0)
> + return len;
> + ASCEBC(cmd_buf, MAX_CMDLEN);
> + EBC_TOUPPER(cmd_buf, MAX_CMDLEN);
> +
> diag_stat_inc(DIAG_STAT_X288);
> - return __diag288(func, timeout, virt_to_phys(cmd), len);
> + return __diag288(func, timeout, virt_to_phys(cmd_buf), len);
> }
>
> static int __diag288_lpar(unsigned int func, unsigned int timeout,
> @@ -104,24 +113,14 @@ static int __diag288_lpar(unsigned int func, unsigned int timeout,
>
> static int wdt_start(struct watchdog_device *dev)
> {
> - char *ebc_cmd;
> - size_t len;
> int ret;
> unsigned int func;
>
> if (MACHINE_IS_VM) {
> - ebc_cmd = kmalloc(MAX_CMDLEN, GFP_KERNEL);
> - if (!ebc_cmd)
> - return -ENOMEM;
> - len = strlcpy(ebc_cmd, wdt_cmd, MAX_CMDLEN);
> - ASCEBC(ebc_cmd, MAX_CMDLEN);
> - EBC_TOUPPER(ebc_cmd, MAX_CMDLEN);
> -
> func = conceal_on ? (WDT_FUNC_INIT | WDT_FUNC_CONCEAL)
> : WDT_FUNC_INIT;
> - ret = __diag288_vm(func, dev->timeout, ebc_cmd, len);
> + ret = __diag288_vm(func, dev->timeout, wdt_cmd);
> WARN_ON(ret != 0);
> - kfree(ebc_cmd);
> } else {
> ret = __diag288_lpar(WDT_FUNC_INIT,
> dev->timeout, LPARWDT_RESTART);
> @@ -146,19 +145,10 @@ static int wdt_stop(struct watchdog_device *dev)
>
> static int wdt_ping(struct watchdog_device *dev)
> {
> - char *ebc_cmd;
> - size_t len;
> int ret;
> unsigned int func;
>
> if (MACHINE_IS_VM) {
> - ebc_cmd = kmalloc(MAX_CMDLEN, GFP_KERNEL);
> - if (!ebc_cmd)
> - return -ENOMEM;
> - len = strlcpy(ebc_cmd, wdt_cmd, MAX_CMDLEN);
> - ASCEBC(ebc_cmd, MAX_CMDLEN);
> - EBC_TOUPPER(ebc_cmd, MAX_CMDLEN);
> -
> /*
> * It seems to be ok to z/VM to use the init function to
> * retrigger the watchdog. On LPAR WDT_FUNC_CHANGE must
> @@ -167,9 +157,8 @@ static int wdt_ping(struct watchdog_device *dev)
> func = conceal_on ? (WDT_FUNC_INIT | WDT_FUNC_CONCEAL)
> : WDT_FUNC_INIT;
>
> - ret = __diag288_vm(func, dev->timeout, ebc_cmd, len);
> + ret = __diag288_vm(func, dev->timeout, wdt_cmd);
> WARN_ON(ret != 0);
> - kfree(ebc_cmd);
> } else {
> ret = __diag288_lpar(WDT_FUNC_CHANGE, dev->timeout, 0);
> }
> @@ -212,25 +201,20 @@ static struct watchdog_device wdt_dev = {
> static int __init diag288_init(void)
> {
> int ret;
> - char ebc_begin[] = {
> - 194, 197, 199, 201, 213
> - };
> - char *ebc_cmd;
>
> watchdog_set_nowayout(&wdt_dev, nowayout_info);
>
> if (MACHINE_IS_VM) {
> - ebc_cmd = kmalloc(sizeof(ebc_begin), GFP_KERNEL);
> - if (!ebc_cmd) {
> + cmd_buf = kmalloc(MAX_CMDLEN, GFP_KERNEL);
> + if (!cmd_buf) {
> pr_err("The watchdog cannot be initialized\n");
> return -ENOMEM;
> }
> - memcpy(ebc_cmd, ebc_begin, sizeof(ebc_begin));
> - ret = __diag288_vm(WDT_FUNC_INIT, 15,
> - ebc_cmd, sizeof(ebc_begin));
> - kfree(ebc_cmd);
> +
> + ret = __diag288_vm(WDT_FUNC_INIT, MIN_INTERVAL, "BEGIN");
> if (ret != 0) {
> pr_err("The watchdog cannot be initialized\n");
> + kfree(cmd_buf);
> return -EINVAL;
> }
> } else {
> @@ -251,6 +235,7 @@ static int __init diag288_init(void)
> static void __exit diag288_exit(void)
> {
> watchdog_unregister_device(&wdt_dev);
> + kfree(cmd_buf);
> }
>
> module_init(diag288_init);
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