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Date: Thu, 19 Apr 2007 12:33:10 -0700
From: Andrew Morton <akpm@...ux-foundation.org>
To: Wim Van Sebroeck <wim@...ana.be>
Cc: linux-kernel@...r.kernel.org, holger@...oeck.de
Subject: Re: RFC: drivers/char/watchdog/pcwd.c +
drivers/char/watchdog/pcwd_pci.c
On Thu, 19 Apr 2007 21:00:55 +0200
Wim Van Sebroeck <wim@...ana.be> wrote:
> Hi Andrew,
>
> > > On Tue, 17 Apr 2007 20:58:49 +0200 Wim Van Sebroeck <wim@...ana.be> wrote:
> > > Would anyone object if we would merge the "full bells and whistles" drivers for
> > > the pcwd isa and pci cards in the kernel tree. (It basically only adds some extra
> > > /proc routines). This would make it easier to maintain the "full bells and whistles"
> > > driver.
> >
> > It's hard to answer that question. Please send the patches out in the
> > usual manner for review and comment.
>
> for the pcwd.c driver the patch would be as follows (see below).
> I'll create the patch for pcwd_pci.c later this week.
>
> #include <linux/module.h> /* For module specific items */
> @@ -65,13 +73,18 @@
> #include <linux/fs.h> /* For file operations */
> #include <linux/ioport.h> /* For io-port access */
> #include <linux/spinlock.h> /* For spin_lock/spin_unlock/... */
> +#include <linux/string.h> /* For string manipulations */
> +#ifdef CONFIG_PROC_FS
> +#include <linux/stat.h> /* For S_IFREG/S_IRUGO/S_IWUSR */
> +#include <linux/proc_fs.h> /* For create_proc_entry/remove_proc_entry/ ... */
> +#endif
Please avoid the ifdefs here if at all possible. They increase the chances
of the build failing as people change configs.
> /* module parameters */
> +#define CELSIUS 0
> +#define FAHRENHEIT 1
> +static int proc_temp_mode = CELSIUS;
> +module_param(proc_temp_mode, int, 0);
> +MODULE_PARM_DESC(proc_temp_mode, "which temperature mode to use in /proc/ 0=Celsius, 1=Fahrenheit (default=0)");
hm, is that a good idea? Making the contents of /proc files dependent upon
some module parameter?
I'd have thought that it would be better to remove this option and either
a) offer two /proc files: one for Celcius, one for Fahrenheit
b) Put both values into the same /proc file (one per line)
c) Just remove the Fahrenheit option altogether - let it join cubits,
furlongs, etc.
I mean, how is an application to make sense of that information if its units
depend upon some module parameter, or a kernel boot option?
> + pcwd_private.card_status=ENABLED;
Missing a ' ' around the '='. Several instances.
> -static int pcwd_get_temperature(int *temperature)
> +static int pcwd_get_temperature(int *temperature, int temp_mode)
> {
> /* check that port 0 gives temperature info and no command results */
> if (pcwd_private.command_mode)
> @@ -543,22 +577,358 @@
> if (!pcwd_private.supports_temp)
> return -ENODEV;
>
> + spin_lock(&pcwd_private.io_lock);
> + *temperature = inb(pcwd_private.io_addr);
> + spin_unlock(&pcwd_private.io_lock);
I doubt if the locking here does anything useful.
> +
> /*
> - * Convert celsius to fahrenheit, since this was
> + * Convert celsius to fahrenheit, this is normally
> * the decided 'standard' for this return value.
> */
> - spin_lock(&pcwd_private.io_lock);
> - *temperature = ((inb(pcwd_private.io_addr)) * 9 / 5) + 32;
> - spin_unlock(&pcwd_private.io_lock);
> + if (temp_mode == FAHRENHEIT)
> + *temperature = (*temperature * 9 / 5) + 32;
>
> if (debug >= DEBUG) {
> - printk(KERN_DEBUG PFX "temperature is: %d F\n",
> - *temperature);
> + printk(KERN_DEBUG PFX "temperature is: %d %s\n",
> + *temperature, (temp_mode == CELSIUS) ? "C" :"F");
> }
>
> return 0;
> }
>
> +#ifdef CONFIG_PROC_FS
> +static int
> +pcwd_reset_pc(void)
static int pcwd_reset_pc(void)
please.
> +static int
> +pcwd_set_timeout(char *sub_command)
Ditto (whole patchset (perhaps whole subsystem ;)))
> +{
> + char *new_sub_command = sub_command;
> + int i;
> +
> + while (*sub_command == ' ')
> + sub_command++;
> + if (sub_command == new_sub_command) {
> + printk(KERN_ERR PFX "illegal timeout argument '%s'\n", sub_command);
> + return 1;
> + }
> + i = simple_strtoul(sub_command, NULL, 0);
darn, we do this sort of gunk in a lot of places. Isn't there some library
function somewhere we can use?
> + if (!pcwd_set_heartbeat(i)) {
> + if (debug >= VERBOSE)
> + printk(KERN_INFO PFX "timeout %d\n", heartbeat);
> + } else {
> + printk(KERN_ERR PFX
> + "illegal timeout argument '%s', should be a number between 2 and 7200\n",
80 columns?
> + sub_command);
> + return 1;
> + }
> + return 0;
> +}
> +
>
> ..
>
> +static void
> +pcwd_user_help(void)
> +{
> + printk(" pcwd proc command interface help:\n");
> + printk(" ping, pong, tickle - tickle the timer\n");
> + printk(" hardreset - reset pc\n");
> + printk(" enable, start - start the watchdog\n");
> + printk(" disable, stop - stop the watchdog\n");
> + printk(" clear - clear trip status and led\n");
> + printk(" verbose, debug, quiet - command reponse\n");
> + printk(" fahrenheit, celsius - display temp in\n");
> + printk(" extended commands:\n");
> + printk(" arm [val] - isa [30,60,90]\n");
> + printk(" timeout [val]\n");
> +}
This could all be done with a single printk() statement.
It's missing a KERN_FOO facility level.
> +static int
> +pcwd_user_command(char *user_command)
> +{
> + if ((strcmp(user_command, "ping") == 0)
> + || (strcmp(user_command, "pong") == 0)
> + || (strcmp(user_command, "tickle") == 0)) {
> + pcwd_keepalive();
> + if (debug >= VERBOSE)
> + printk(KERN_INFO PFX "ping...\n");
> + } else if ((strcmp(user_command, "enable") == 0)
> + || (strcmp(user_command, "start") == 0)) {
> + if (!pcwd_start()) {
> + if (debug >= VERBOSE)
> + printk(KERN_INFO PFX "watchdog enabled.\n");
> + }
> + } else if ((strcmp(user_command, "disable") == 0)
> + || (strcmp(user_command, "stop") == 0)) {
> + if (!pcwd_stop()) {
> + if (debug >= VERBOSE)
> + printk(KERN_INFO PFX "watchdog disabled!\n");
> + }
> + } else if (strcmp(user_command, "clear") == 0) {
> + pcwd_clear_status();
> + if (debug >= VERBOSE)
> + printk(KERN_INFO PFX "cleared trip status\n");
> + } else if (strcmp(user_command, "hardreset") == 0) {
> + pcwd_reset_pc();
> + if (debug >= VERBOSE)
> + printk(KERN_INFO PFX "hardreset PC!\n");
> + } else if (strcmp(user_command, "quiet") == 0) {
> + debug = QUIET;
> + } else if (strcmp(user_command, "verbose") == 0) {
> + debug = VERBOSE;
> + printk(KERN_INFO PFX "verbose mode on.\n");
> + } else if (strcmp(user_command, "debug") == 0) {
> + debug = DEBUG;
> + printk(KERN_INFO PFX "debug mode on.\n");
> + } else if (strcmp(user_command, "celsius") == 0) {
> + proc_temp_mode = CELSIUS;
> + if (debug >= VERBOSE)
> + printk(KERN_INFO PFX "display temp in Celsius.\n");
> + } else if (strcmp(user_command, "fahrenheit") == 0) {
> + proc_temp_mode = FAHRENHEIT;
> + if (debug >= VERBOSE)
> + printk(KERN_INFO PFX "display temp in Fahrenheit.\n");
> + } else if (strcmp(user_command, "help") == 0) {
> + pcwd_user_help();
> + } else if (strncmp(user_command, "arm", 3) == 0) {
> + if ((pcwd_private.fw_ver_str[0] >= '1')
> + && (pcwd_private.fw_ver_str[2] >= '2')) {
> + if (pcwd_set_arm(&user_command[3])) {
> + printk(KERN_ERR PFX "arm FAILED.\n");
> + return 0;
> + }
> + } else {
> + printk(KERN_ERR
> + "pcwd: ISA Card and firmware > 1.20 needed.\n");
> + return 0;
> + }
> + } else if (strncmp(user_command, "timeout", 7) == 0) {
> + if (pcwd_set_timeout(&user_command[7])) {
> + printk(KERN_ERR PFX "timeout FAILED.\n");
> + return 0;
> + }
> + } else {
> + printk(KERN_ERR "illegal user command: '%s'\n", user_command);
> + pcwd_user_help();
> + return 0;
> + }
> + return 1;
> +}
parse, parse, parse, parse. We really do need stronger libraries for this
sort of thing.
> +static int
> +pcwd_write_proc(struct file *file, const char *buffer,
> + unsigned long count, void *data)
> +{
> + char command_buffer[80];
> + int rc, length;
> +
> + /* write only allowed for root users */
> + if (current->euid != 0)
> + return -EACCES;
Are the permissions on the /proc file not sufficient?
Surely it's wrong to be testing for root anyway. capable(CAP_SYS_ADMIN)
would be more typical. Or CAP_RAW_IO or something.
But not this.
> + if (count > sizeof (command_buffer) - 1)
> + return -EINVAL;
> +
> + if (copy_from_user(command_buffer, buffer, count))
> + return -EFAULT;
> +
> + command_buffer[count] = '\0';
> + length = strlen(command_buffer);
> + if (command_buffer[length - 1] == '\n')
> + command_buffer[--length] = '\0';
> +
> + spin_lock(&pcwd_private.proc_lock);
> + rc = pcwd_user_command(command_buffer);
> + spin_unlock(&pcwd_private.proc_lock);
> + return (rc ? count : -EBUSY);
> +}
> +
> +/* This macro frees the machine specific function from bounds checking and
> + * * this like that... [from nvram.c]*/
> +#define PRINT_PROC(fmt,args...) \
> + do { \
> + *len += sprintf( buffer+*len, fmt, ##args ); \
> + if (*begin + *len > offset + size) \
> + return( 0 ); \
> + if (*begin + *len < offset) { \
> + *begin += *len; \
> + *len = 0; \
> + } \
> + } while(0)
A `return' hidden in a macro like this is pretty foul. We'd prefer that
new instances not be added to the kernel.
Can we please find a tasteful way of reimplementing this? Cannot the
seq_file interface be used?
> +static int
> +pcwd_proc_info(unsigned char *buf, char *buffer, int *len,
> + off_t * begin, off_t offset, int size)
> +{
> + int sw, i;
> +
> + PRINT_PROC("%s\n", DRIVER_VERSION);
> +
> + if (pcwd_private.revision == PCWD_REVISION_C) {
> + PRINT_PROC("Firmware : Version %s\n", pcwd_private.fw_ver_str);
> + PRINT_PROC("Option Switch: Delay Time ");
> + sw = pcwd_get_option_switches();
> + switch (sw & 0x07) {
> + case 0:
> + PRINT_PROC("20 s");
> + break;
> + case 1:
> + PRINT_PROC("40 s");
> + break;
> + case 2:
> + PRINT_PROC("1 min");
> + break;
> + case 3:
> + PRINT_PROC("5 min");
> + break;
> + case 4:
> + PRINT_PROC("10 min");
> + break;
> + case 5:
> + PRINT_PROC("30 min");
> + break;
> + case 6:
> + PRINT_PROC("1 h");
> + break;
> + case 7:
> + PRINT_PROC("2 h");
> + break;
> + }
> + PRINT_PROC((sw & 0x08) ? ", POD on" : ", POD off");
> + PRINT_PROC((sw & 0x10) ? ", TRE on" : ", TRE off");
> + PRINT_PROC((sw & 0x20) ? ", R2M on" : ", R2M off");
> + PRINT_PROC((sw & 0x40) ? ", R1M on" : ", R1M off");
> + PRINT_PROC((sw & 0x80) ? ", RTM on\n" : ", RTM off\n");
> + } else {
> + PRINT_PROC("Firmware ROM not present\n");
> + }
> +
> + PRINT_PROC("Temperature : ");
> + if (pcwd_private.supports_temp && (!pcwd_get_temperature(&i, proc_temp_mode))) {
> + PRINT_PROC("%d ", i);
> + PRINT_PROC((proc_temp_mode == CELSIUS) ? "__C\n" : "__F\n");
> + } else {
> + PRINT_PROC("Card without temp option\n");
> + }
> +
> + if (pcwd_private.card_status == ENABLED)
> + PRINT_PROC("Card status : Timer enabled\n");
> + else
> + PRINT_PROC("Card status : Timer disabled\n");
> +
> + spin_lock(&pcwd_private.io_lock);
> + if (pcwd_private.revision == PCWD_REVISION_A) {
> + sw = inb_p(pcwd_private.io_addr) & WD_WDRST;
> + } else {
> + sw = inb_p(pcwd_private.io_addr + 1) & WD_REVC_WTRP;
> + }
> + spin_unlock(&pcwd_private.io_lock);
> + PRINT_PROC("Reboot status: ");
> + PRINT_PROC(sw ? "Tripped\n" : "Not tripped\n");
> +
> + if ((pcwd_private.boot_status & WDIOF_CARDRESET) && (pcwd_private.boot_status & WDIOF_OVERHEAT)) {
> + PRINT_PROC("Boot status : CPU Overheat + Watchdog caused reboot\n");
> + } else if (pcwd_private.boot_status & WDIOF_CARDRESET) {
> + PRINT_PROC("Boot status : Watchdog caused reboot\n");
> + } else if (pcwd_private.boot_status & WDIOF_OVERHEAT) {
> + PRINT_PROC("Boot status : CPU Overheat\n");
> + } else {
> + PRINT_PROC("Boot status : Cold boot or reset\n");
> + }
Lots of braces can (shold) be removed in here.
> + // PRINT_PROC("Ping Count : %d\n", ping_counter);
> + return 1;
> +}
> +
> +static int
> +pcwd_read_proc(char *buffer, char **start, off_t offset,
> + int size, int *eof, void *data)
> +{
> + int len = 0;
> + off_t begin = 0;
> +
> + spin_lock(&pcwd_private.proc_lock);
> + *eof = pcwd_proc_info(NULL, buffer, &len, &begin, offset, size);
> + spin_unlock(&pcwd_private.proc_lock);
> +
> + if (offset >= begin + len)
> + return (0);
> + *start = buffer + (offset - begin); // CORRECTED !!!!
> + return (size < begin + len - offset ? size : begin + len - offset);
> +}
> +#endif /* PROC_FS */
> +
>
> ...
>
> +#ifdef CONFIG_PROC_FS
> + if ((pcwd_private.proc_pcwd =
> + create_proc_entry(WATCHDOG_NAME, S_IFREG | S_IRUGO | S_IWUSR, 0))) {
> + pcwd_private.proc_pcwd->read_proc = pcwd_read_proc;
> + pcwd_private.proc_pcwd->write_proc = pcwd_write_proc;
> + }
> +#endif
We prefer
a = b();
if (a)
over
if ((a = b())
-
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