[PATCH] EDAC: switch to kthread_ API

This patch was originally posted by Christoph Hellwig (see
http://lkml.org/lkml/2006/2/14/331):

"Christoph Hellwig" <hch@lst.de> wrote:
> Use the kthread_ API instead of opencoding lots of hairy code for kernel
> thread creation and teardown, including tasklist_lock abuse.
>

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: David S. Peterson <dsp@llnl.gov>
Cc: <dave_peterson@pobox.com>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 10 insertions, 78 deletions

diff --git a/drivers/edac/edac_mc.c b/drivers/edac/edac_mc.c
index 9c205274c1cb..8a7a3ab745aa 100644
--- a/drivers/edac/edac_mc.c
+++ b/drivers/edac/edac_mc.c
@@ -29,6 +29,7 @@
 #include <linux/list.h>
 #include <linux/sysdev.h>
 #include <linux/ctype.h>
+#include <linux/kthread.h>
 
 #include <asm/uaccess.h>
 #include <asm/page.h>
@@ -64,6 +65,8 @@ static atomic_t pci_parity_count = ATOMIC_INIT(0);
 static DECLARE_MUTEX(mem_ctls_mutex);
 static struct list_head mc_devices = LIST_HEAD_INIT(mc_devices);
 
+static struct task_struct *edac_thread;
+
 /* Structure of the whitelist and blacklist arrays */
 struct edac_pci_device_list {
         unsigned int  vendor;           /* Vendor ID */
@@ -2073,7 +2076,6 @@ static inline void check_mc_devices (void)
  */
 static void do_edac_check(void)
 {
-
         debugf3("MC: " __FILE__ ": %s()\n", __func__);
 
         check_mc_devices();
@@ -2081,62 +2083,16 @@ static void do_edac_check(void)
         do_pci_parity_check();
 }
 
-
-/*
- * EDAC thread state information
- */
-struct bs_thread_info
-{
-        struct task_struct *task;
-        struct completion *event;
-        char *name;
-        void (*run)(void);
-};
-
-static struct bs_thread_info bs_thread;
-
-/*
- *  edac_kernel_thread
- *      This the kernel thread that processes edac operations
- *      in a normal thread environment
- */
 static int edac_kernel_thread(void *arg)
 {
-        struct bs_thread_info *thread = (struct bs_thread_info *) arg;
-
-        /* detach thread */
-        daemonize(thread->name);
-
-        current->exit_signal = SIGCHLD;
-        allow_signal(SIGKILL);
-        thread->task = current;
-
-        /* indicate to starting task we have started */
-        complete(thread->event);
-
-        /* loop forever, until we are told to stop */
-        while(thread->run != NULL) {
-                void (*run)(void);
-
-                /* call the function to check the memory controllers */
-                run = thread->run;
-                if (run)
-                        run();
-
-                if (signal_pending(current))
-                        flush_signals(current);
-
-                /* ensure we are interruptable */
-                set_current_state(TASK_INTERRUPTIBLE);
+        while (!kthread_should_stop()) {
+                do_edac_check();
 
                 /* goto sleep for the interval */
-                schedule_timeout((HZ * poll_msec) / 1000);
+                schedule_timeout_interruptible((HZ * poll_msec) / 1000);
                 try_to_freeze();
         }
 
-        /* notify waiter that we are exiting */
-        complete(thread->event);
-
         return 0;
 }
 
@@ -2146,9 +2102,6 @@ static int edac_kernel_thread(void *arg)
  */
 static int __init edac_mc_init(void)
 {
-        int ret;
-        struct completion event;
-
         printk(KERN_INFO "MC: " __FILE__ " version " EDAC_MC_VERSION "\n");
 
         /*
@@ -2176,24 +2129,15 @@ static int __init edac_mc_init(void)
                 return -ENODEV;
         }
 
-        /* Create our kernel thread */
-        init_completion(&event);
-        bs_thread.event = &event;
-        bs_thread.name = "kedac";
-        bs_thread.run = do_edac_check;
-
         /* create our kernel thread */
-        ret = kernel_thread(edac_kernel_thread, &bs_thread, CLONE_KERNEL);
-        if (ret < 0) {
+        edac_thread = kthread_run(edac_kernel_thread, NULL, "kedac");
+        if (IS_ERR(edac_thread)) {
                 /* remove the sysfs entries */
                 edac_sysfs_memctrl_teardown();
                 edac_sysfs_pci_teardown();
-                return -ENOMEM;
+                return PTR_ERR(edac_thread);
         }
 
-        /* wait for our kernel theard ack that it is up and running */
-        wait_for_completion(&event);
-
         return 0;
 }
 
@@ -2204,21 +2148,9 @@ static int __init edac_mc_init(void)
  */
 static void __exit edac_mc_exit(void)
 {
-        struct completion event;
-
         debugf0("MC: " __FILE__ ": %s()\n", __func__);
 
-        init_completion(&event);
-        bs_thread.event = &event;
-
-        /* As soon as ->run is set to NULL, the task could disappear,
-         * so we need to hold tasklist_lock until we have sent the signal
-         */
-        read_lock(&tasklist_lock);
-        bs_thread.run = NULL;
-        send_sig(SIGKILL, bs_thread.task, 1);
-        read_unlock(&tasklist_lock);
-        wait_for_completion(&event);
+        kthread_stop(edac_thread);
 
         /* tear down the sysfs device */
         edac_sysfs_memctrl_teardown();