[PATCH] IPMI Watchdog handling updates

Makes the IPMI watchdog more consistent with the other watchdog drivers.

I have tested this and it seems to work correctly.  I also added docs for
the interface change.

- support disabling watchdog by writing 'V' to device.
- unify printk()
- use atomic bit operations on ipmi_wdog_open
Signed-off-by: Arkadiusz Miskiewicz <arekm@pld-linux.org>
Signed-off-by: Corey Minyard <minyard@acm.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

Documentation/IPMI.txt

@@ -496,3 +496,8 @@ start a 120 timer if it is running to make sure the reboot occurs.
 Note that if you use the NMI preaction for the watchdog, you MUST
 NOT use nmi watchdog mode 1.  If you use the NMI watchdog, you
 must use mode 2.
+
+Once you open the watchdog timer, you must write a 'V' character to the
+device to close it, or the timer will not stop.  This is a new semantic
+for the driver, but makes it consistent with the rest of the watchdog
+drivers in Linux.

drivers/char/ipmi/ipmi_watchdog.c

@@ -51,6 +51,8 @@
 #include <asm/apic.h>
 #endif
 
+#define	PFX "IPMI Watchdog: "
+
 #define IPMI_WATCHDOG_VERSION "v32"
 
 /*
@@ -160,6 +162,7 @@ static char data_to_read = 0;
 static DECLARE_WAIT_QUEUE_HEAD(read_q);
 static struct fasync_struct *fasync_q = NULL;
 static char pretimeout_since_last_heartbeat = 0;
+static char expect_close;
 
 /* If true, the driver will start running as soon as it is configured
    and ready. */
@@ -191,7 +194,7 @@ static unsigned char ipmi_watchdog_state = WDOG_TIMEOUT_NONE;
 static int ipmi_ignore_heartbeat = 0;
 
 /* Is someone using the watchdog?  Only one user is allowed. */
-static int ipmi_wdog_open = 0;
+static unsigned long ipmi_wdog_open = 0;
 
 /* If set to 1, the heartbeat command will set the state to reset and
    start the timer.  The timer doesn't normally run when the driver is
@@ -287,7 +290,7 @@ static int i_ipmi_set_timeout(struct ipmi_smi_msg  *smi_msg,
 				      recv_msg,
 				      1);
 	if (rv) {
-		printk(KERN_WARNING "IPMI Watchdog, set timeout error: %d\n",
+		printk(KERN_WARNING PFX "set timeout error: %d\n",
 		       rv);
 	}
 
@@ -464,7 +467,7 @@ static int ipmi_heartbeat(void)
 				      1);
 	if (rv) {
 		up(&heartbeat_lock);
-		printk(KERN_WARNING "IPMI Watchdog, heartbeat failure: %d\n",
+		printk(KERN_WARNING PFX "heartbeat failure: %d\n",
 		       rv);
 		return rv;
 	}
@@ -599,6 +602,21 @@ static ssize_t ipmi_write(struct file *file,
 	int rv;
 
 	if (len) {
+	    	if (!nowayout) {
+		    	size_t i;
+
+			/* In case it was set long ago */
+			expect_close = 0;
+
+    			for (i = 0; i != len; i++) {
+				char c;
+
+				if (get_user(c, buf + i))
+					return -EFAULT;
+				if (c == 'V')
+					expect_close = 42;
+			}
+		}
 		rv = ipmi_heartbeat();
 		if (rv)
 			return rv;
@@ -662,11 +680,9 @@ static int ipmi_open(struct inode *ino, struct file *filep)
         switch (iminor(ino))
         {
                 case WATCHDOG_MINOR:
-                    if (ipmi_wdog_open)
+		    if(test_and_set_bit(0, &ipmi_wdog_open))
                         return -EBUSY;
 
-                    ipmi_wdog_open = 1;
-
 		    /* Don't start the timer now, let it start on the
 		       first heartbeat. */
 		    ipmi_start_timer_on_heartbeat = 1;
@@ -704,14 +720,18 @@ static int ipmi_close(struct inode *ino, struct file *filep)
 {
 	if (iminor(ino)==WATCHDOG_MINOR)
 	{
-		if (!nowayout) {
+		if (expect_close == 42) {
 			ipmi_watchdog_state = WDOG_TIMEOUT_NONE;
 			ipmi_set_timeout(IPMI_SET_TIMEOUT_NO_HB);
+			clear_bit(0, &ipmi_wdog_open);
+		} else {
+			printk(KERN_CRIT PFX "Unexpected close, not stopping watchdog!\n");
+			ipmi_heartbeat();
 		}
-	        ipmi_wdog_open = 0;
 	}
 
 	ipmi_fasync (-1, filep, 0);
+	expect_close = 0;
 
 	return 0;
 }
@@ -739,7 +759,7 @@ static void ipmi_wdog_msg_handler(struct ipmi_recv_msg *msg,
 				  void                 *handler_data)
 {
 	if (msg->msg.data[0] != 0) {
-		printk(KERN_ERR "IPMI Watchdog response: Error %x on cmd %x\n",
+		printk(KERN_ERR PFX "response: Error %x on cmd %x\n",
 		       msg->msg.data[0],
 		       msg->msg.cmd);
 	}
@@ -784,7 +804,7 @@ static void ipmi_register_watchdog(int ipmi_intf)
 
 	rv = ipmi_create_user(ipmi_intf, &ipmi_hndlrs, NULL, &watchdog_user);
 	if (rv < 0) {
-		printk("IPMI watchdog: Unable to register with ipmi\n");
+		printk(KERN_CRIT PFX "Unable to register with ipmi\n");
 		goto out;
 	}
 
@@ -796,7 +816,7 @@ static void ipmi_register_watchdog(int ipmi_intf)
 	if (rv < 0) {
 		ipmi_destroy_user(watchdog_user);
 		watchdog_user = NULL;
-		printk("IPMI watchdog: Unable to register misc device\n");
+		printk(KERN_CRIT PFX "Unable to register misc device\n");
 	}
 
  out:
@@ -807,7 +827,7 @@ static void ipmi_register_watchdog(int ipmi_intf)
 		start_now = 0; /* Disable this function after first startup. */
 		ipmi_watchdog_state = action_val;
 		ipmi_set_timeout(IPMI_SET_TIMEOUT_FORCE_HB);
-		printk("Starting IPMI Watchdog now!\n");
+		printk(KERN_INFO PFX "Starting now!\n");
 	}
 }
 
@@ -818,7 +838,7 @@ ipmi_nmi(void *dev_id, struct pt_regs *regs, int cpu, int handled)
 	/* If no one else handled the NMI, we assume it was the IPMI
            watchdog. */
 	if ((!handled) && (preop_val == WDOG_PREOP_PANIC))
-		panic("IPMI watchdog pre-timeout");
+		panic(PFX "pre-timeout");
 
 	/* On some machines, the heartbeat will give
 	   an error and not work unless we re-enable
@@ -924,7 +944,7 @@ static int __init ipmi_wdog_init(void)
 {
 	int rv;
 
-	printk(KERN_INFO "IPMI watchdog driver version "
+	printk(KERN_INFO PFX "driver version "
 	       IPMI_WATCHDOG_VERSION "\n");
 
 	if (strcmp(action, "reset") == 0) {
@@ -937,7 +957,7 @@ static int __init ipmi_wdog_init(void)
 		action_val = WDOG_TIMEOUT_POWER_DOWN;
 	} else {
 		action_val = WDOG_TIMEOUT_RESET;
-		printk("ipmi_watchdog: Unknown action '%s', defaulting to"
+		printk(KERN_INFO PFX "Unknown action '%s', defaulting to"
 		       " reset\n", action);
 	}
 
@@ -953,7 +973,7 @@ static int __init ipmi_wdog_init(void)
 		preaction_val = WDOG_PRETIMEOUT_MSG_INT;
 	} else {
 		preaction_val = WDOG_PRETIMEOUT_NONE;
-		printk("ipmi_watchdog: Unknown preaction '%s', defaulting to"
+		printk(KERN_INFO PFX "Unknown preaction '%s', defaulting to"
 		       " none\n", preaction);
 	}
 
@@ -965,23 +985,21 @@ static int __init ipmi_wdog_init(void)
 		preop_val = WDOG_PREOP_GIVE_DATA;
 	} else {
 		preop_val = WDOG_PREOP_NONE;
-		printk("ipmi_watchdog: Unknown preop '%s', defaulting to"
+		printk(KERN_INFO PFX "Unknown preop '%s', defaulting to"
 		       " none\n", preop);
 	}
 
 #ifdef HAVE_NMI_HANDLER
 	if (preaction_val == WDOG_PRETIMEOUT_NMI) {
 		if (preop_val == WDOG_PREOP_GIVE_DATA) {
-			printk(KERN_WARNING
-			       "ipmi_watchdog: Pretimeout op is to give data"
+			printk(KERN_WARNING PFX "Pretimeout op is to give data"
 			       " but NMI pretimeout is enabled, setting"
 			       " pretimeout op to none\n");
 			preop_val = WDOG_PREOP_NONE;
 		}
 #ifdef CONFIG_X86_LOCAL_APIC
 		if (nmi_watchdog == NMI_IO_APIC) {
-			printk(KERN_WARNING
-			       "ipmi_watchdog: nmi_watchdog is set to IO APIC"
+			printk(KERN_WARNING PFX "nmi_watchdog is set to IO APIC"
 			       " mode (value is %d), that is incompatible"
 			       " with using NMI in the IPMI watchdog."
 			       " Disabling IPMI nmi pretimeout.\n",
@@ -991,8 +1009,7 @@ static int __init ipmi_wdog_init(void)
 #endif
 		rv = request_nmi(&ipmi_nmi_handler);
 		if (rv) {
-			printk(KERN_WARNING
-			       "ipmi_watchdog: Can't register nmi handler\n");
+			printk(KERN_WARNING PFX "Can't register nmi handler\n");
 			return rv;
 		}
 #ifdef CONFIG_X86_LOCAL_APIC
@@ -1007,8 +1024,7 @@ static int __init ipmi_wdog_init(void)
 		if (preaction_val == WDOG_PRETIMEOUT_NMI)
 			release_nmi(&ipmi_nmi_handler);
 #endif
-		printk(KERN_WARNING
-		       "ipmi_watchdog: can't register smi watcher\n");
+		printk(KERN_WARNING PFX "can't register smi watcher\n");
 		return rv;
 	}
 
@@ -1053,8 +1069,7 @@ static __exit void ipmi_unregister_watchdog(void)
 	/* Disconnect from IPMI. */
 	rv = ipmi_destroy_user(watchdog_user);
 	if (rv) {
-		printk(KERN_WARNING
-		       "IPMI Watchdog, error unlinking from IPMI: %d\n",
+		printk(KERN_WARNING PFX "error unlinking from IPMI: %d\n",
 		       rv);
 	}
 	watchdog_user = NULL;