linux-kernel - [PATCH v3 21/47] ipmi: Register with kernel power-off handler

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Message-Id: <1414425354-10359-22-git-send-email-linux@roeck-us.net>
Date:	Mon, 27 Oct 2014 08:55:28 -0700
From:	Guenter Roeck <linux@...ck-us.net>
To:	linux-kernel@...r.kernel.org
Cc:	linux-pm@...r.kernel.org, Guenter Roeck <linux@...ck-us.net>,
	Corey Minyard <minyard@....org>,
	openipmi-developer@...ts.sourceforge.net
Subject: [PATCH v3 21/47] ipmi: Register with kernel power-off handler

Register with kernel power-off handler instead of setting pm_power_off
directly. Register with high priority to reflect that the original code
overwrites pm_power_off unconditionally.

Register power-off handler after the ipmi system is ready, and unregister
it prior to cleanup. This avoids having to check for the ready variable
in the poweroff callback.

Reviewed-by: Corey Minyard <minyard@....org>
Signed-off-by: Guenter Roeck <linux@...ck-us.net>
---
v3:
- Replace poweroff in all newly introduced variables and in text
  with power_off or power-off as appropriate
- Replace POWEROFF_PRIORITY_xxx with POWER_OFF_PRIORITY_xxx
v2:
- Use define to specify poweroff handler priority
- Use pr_warn instead of pr_err
- Call unregister_power_off_handler on exit only if not already unregistered

 drivers/char/ipmi/ipmi_poweroff.c | 29 ++++++++++++++++++-----------
 1 file changed, 18 insertions(+), 11 deletions(-)

diff --git a/drivers/char/ipmi/ipmi_poweroff.c b/drivers/char/ipmi/ipmi_poweroff.c
index 9f2e3be..0698e1c 100644
--- a/drivers/char/ipmi/ipmi_poweroff.c
+++ b/drivers/char/ipmi/ipmi_poweroff.c
@@ -36,6 +36,7 @@
 #include <linux/proc_fs.h>
 #include <linux/string.h>
 #include <linux/completion.h>
+#include <linux/notifier.h>
 #include <linux/pm.h>
 #include <linux/kdev_t.h>
 #include <linux/ipmi.h>
@@ -63,9 +64,6 @@ static ipmi_user_t ipmi_user;
 static int ipmi_ifnum;
 static void (*specific_poweroff_func)(ipmi_user_t user);
 
-/* Holds the old poweroff function so we can restore it on removal. */
-static void (*old_poweroff_func)(void);
-
 static int set_param_ifnum(const char *val, struct kernel_param *kp)
 {
 	int rv = param_set_int(val, kp);
@@ -544,15 +542,20 @@ static struct poweroff_function poweroff_functions[] = {
 
 
 /* Called on a powerdown request. */
-static void ipmi_poweroff_function(void)
+static int ipmi_poweroff_function(struct notifier_block *this,
+				  unsigned long unused1, void *unused2)
 {
-	if (!ready)
-		return;
-
 	/* Use run-to-completion mode, since interrupts may be off. */
 	specific_poweroff_func(ipmi_user);
+
+	return NOTIFY_DONE;
 }
 
+static struct notifier_block ipmi_power_off_nb = {
+	.notifier_call = ipmi_poweroff_function,
+	.priority = POWER_OFF_PRIORITY_HIGH,
+};
+
 /* Wait for an IPMI interface to be installed, the first one installed
    will be grabbed by this code and used to perform the powerdown. */
 static void ipmi_po_new_smi(int if_num, struct device *device)
@@ -631,9 +634,12 @@ static void ipmi_po_new_smi(int if_num, struct device *device)
 	printk(KERN_INFO PFX "Found a %s style poweroff function\n",
 	       poweroff_functions[i].platform_type);
 	specific_poweroff_func = poweroff_functions[i].poweroff_func;
-	old_poweroff_func = pm_power_off;
-	pm_power_off = ipmi_poweroff_function;
+
 	ready = 1;
+
+	rv = register_power_off_handler(&ipmi_power_off_nb);
+	if (rv)
+		pr_warn(PFX "failed to register power-off handler\n");
 }
 
 static void ipmi_po_smi_gone(int if_num)
@@ -644,9 +650,10 @@ static void ipmi_po_smi_gone(int if_num)
 	if (ipmi_ifnum != if_num)
 		return;
 
+	unregister_power_off_handler(&ipmi_power_off_nb);
+
 	ready = 0;
 	ipmi_destroy_user(ipmi_user);
-	pm_power_off = old_poweroff_func;
 }
 
 static struct ipmi_smi_watcher smi_watcher = {
@@ -733,11 +740,11 @@ static void __exit ipmi_poweroff_cleanup(void)
 	ipmi_smi_watcher_unregister(&smi_watcher);
 
 	if (ready) {
+		unregister_power_off_handler(&ipmi_power_off_nb);
 		rv = ipmi_destroy_user(ipmi_user);
 		if (rv)
 			printk(KERN_ERR PFX "could not cleanup the IPMI"
 			       " user: 0x%x\n", rv);
-		pm_power_off = old_poweroff_func;
 	}
 }
 module_exit(ipmi_poweroff_cleanup);
-- 
1.9.1

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