[PATCH] ieee1394: nodemgr: switch to kthread api, replace reset semaphore

Convert nodemgr's host thread from kernel_thread to kthread and its
sleep/restart mechanism from a counting semaphore to a schedule()/
wake_up_process() scheme.

Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
Signed-off-by: Ben Collins <bcollins@ubuntu.com>

1 files changed, 41 insertions, 79 deletions

diff --git a/drivers/ieee1394/nodemgr.c b/drivers/ieee1394/nodemgr.c
index 04b62eca647b..2e6dc5990cef 100644
--- a/drivers/ieee1394/nodemgr.c
+++ b/drivers/ieee1394/nodemgr.c
@@ -12,8 +12,8 @@
 #include <linux/kernel.h>
 #include <linux/list.h>
 #include <linux/slab.h>
-#include <linux/completion.h>
 #include <linux/delay.h>
+#include <linux/kthread.h>
 #include <linux/moduleparam.h>
 #include <asm/atomic.h>
 
@@ -163,11 +163,7 @@ static DECLARE_MUTEX(nodemgr_serialize);
 struct host_info {
         struct hpsb_host *host;
         struct list_head list;
-        struct completion exited;
-        struct semaphore reset_sem;
-        int pid;
-        char daemon_name[15];
-        int kill_me;
+        struct task_struct *thread;
 };
 
 static int nodemgr_bus_match(struct device * dev, struct device_driver * drv);
@@ -1477,9 +1473,8 @@ static void nodemgr_node_probe(struct host_info *hi, int generation)
         /* If we had a bus reset while we were scanning the bus, it is
          * possible that we did not probe all nodes.  In that case, we
          * skip the clean up for now, since we could remove nodes that
-         * were still on the bus.  The bus reset increased hi->reset_sem,
-         * so there's a bus scan pending which will do the clean up
-         * eventually.
+         * were still on the bus.  Another bus scan is pending which will
+         * do the clean up eventually.
          *
          * Now let's tell the bus to rescan our devices. This may seem
          * like overhead, but the driver-model core will only scan a
@@ -1607,41 +1602,37 @@ static int nodemgr_host_thread(void *__hi)
 {
         struct host_info *hi = (struct host_info *)__hi;
         struct hpsb_host *host = hi->host;
-        int reset_cycles = 0;
-
-        /* No userlevel access needed */
-        daemonize(hi->daemon_name);
+        unsigned int g, generation = get_hpsb_generation(host) - 1;
+        int i, reset_cycles = 0;
 
         /* Setup our device-model entries */
         nodemgr_create_host_dev_files(host);
 
-        /* Sit and wait for a signal to probe the nodes on the bus. This
-         * happens when we get a bus reset. */
-        while (1) {
-                unsigned int generation = 0;
-                int i;
+        for (;;) {
+                /* Sleep until next bus reset */
+                set_current_state(TASK_INTERRUPTIBLE);
+                if (get_hpsb_generation(host) == generation)
+                        schedule();
+                __set_current_state(TASK_RUNNING);
+
+                /* Thread may have been woken up to freeze or to exit */
+                if (try_to_freeze())
+                        continue;
+                if (kthread_should_stop())
+                        goto exit;
 
-                if (down_interruptible(&hi->reset_sem) ||
-                    down_interruptible(&nodemgr_serialize)) {
+                if (down_interruptible(&nodemgr_serialize)) {
                         if (try_to_freeze())
                                 continue;
-                        printk("NodeMgr: received unexpected signal?!\n" );
-                        break;
-                }
-
-                if (hi->kill_me) {
-                        up(&nodemgr_serialize);
-                        break;
+                        goto exit;
                 }
 
                 /* Pause for 1/4 second in 1/16 second intervals,
                  * to make sure things settle down. */
+                g = get_hpsb_generation(host);
                 for (i = 0; i < 4 ; i++) {
-                        set_current_state(TASK_INTERRUPTIBLE);
-                        if (msleep_interruptible(63)) {
-                                up(&nodemgr_serialize);
-                                goto caught_signal;
-                        }
+                        if (msleep_interruptible(63) || kthread_should_stop())
+                                goto unlock_exit;
 
                         /* Now get the generation in which the node ID's we collect
                          * are valid.  During the bus scan we will use this generation
@@ -1652,14 +1643,8 @@ static int nodemgr_host_thread(void *__hi)
 
                         /* If we get a reset before we are done waiting, then
                          * start the the waiting over again */
-                        while (!down_trylock(&hi->reset_sem))
-                                i = 0;
-
-                        /* Check the kill_me again */
-                        if (hi->kill_me) {
-                                up(&nodemgr_serialize);
-                                goto caught_signal;
-                        }
+                        if (generation != g)
+                                g = generation, i = 0;
                 }
 
                 if (!nodemgr_check_irm_capability(host, reset_cycles) ||
@@ -1685,11 +1670,11 @@ static int nodemgr_host_thread(void *__hi)
 
                 up(&nodemgr_serialize);
         }
-
-caught_signal:
+unlock_exit:
+        up(&nodemgr_serialize);
+exit:
         HPSB_VERBOSE("NodeMgr: Exiting thread");
-
-        complete_and_exit(&hi->exited, 0);
+        return 0;
 }
 
 int nodemgr_for_each_host(void *__data, int (*cb)(struct hpsb_host *, void *))
@@ -1749,41 +1734,27 @@ static void nodemgr_add_host(struct hpsb_host *host)
         struct host_info *hi;
 
         hi = hpsb_create_hostinfo(&nodemgr_highlevel, host, sizeof(*hi));
-
         if (!hi) {
-                HPSB_ERR ("NodeMgr: out of memory in add host");
+                HPSB_ERR("NodeMgr: out of memory in add host");
                 return;
         }
-
         hi->host = host;
-        init_completion(&hi->exited);
-        sema_init(&hi->reset_sem, 0);
-
-        sprintf(hi->daemon_name, "knodemgrd_%d", host->id);
-
-        hi->pid = kernel_thread(nodemgr_host_thread, hi, CLONE_KERNEL);
-
-        if (hi->pid < 0) {
-                HPSB_ERR ("NodeMgr: failed to start %s thread for %s",
-                          hi->daemon_name, host->driver->name);
+        hi->thread = kthread_run(nodemgr_host_thread, hi, "knodemgrd_%d",
+                                 host->id);
+        if (IS_ERR(hi->thread)) {
+                HPSB_ERR("NodeMgr: cannot start thread for host %d", host->id);
                 hpsb_destroy_hostinfo(&nodemgr_highlevel, host);
-                return;
         }
-
-        return;
 }
 
 static void nodemgr_host_reset(struct hpsb_host *host)
 {
         struct host_info *hi = hpsb_get_hostinfo(&nodemgr_highlevel, host);
 
-        if (hi != NULL) {
-                HPSB_VERBOSE("NodeMgr: Processing host reset for %s", hi->daemon_name);
-                up(&hi->reset_sem);
-        } else
-                HPSB_ERR ("NodeMgr: could not process reset of unused host");
-
-        return;
+        if (hi) {
+                HPSB_VERBOSE("NodeMgr: Processing reset for host %d", host->id);
+                wake_up_process(hi->thread);
+        }
 }
 
 static void nodemgr_remove_host(struct hpsb_host *host)
@@ -1791,18 +1762,9 @@ static void nodemgr_remove_host(struct hpsb_host *host)
         struct host_info *hi = hpsb_get_hostinfo(&nodemgr_highlevel, host);
 
         if (hi) {
-                if (hi->pid >= 0) {
-                        hi->kill_me = 1;
-                        mb();
-                        up(&hi->reset_sem);
-                        wait_for_completion(&hi->exited);
-                        nodemgr_remove_host_dev(&host->device);
-                }
-        } else
-                HPSB_ERR("NodeMgr: host %s does not exist, cannot remove",
-                         host->driver->name);
-
-        return;
+                kthread_stop(hi->thread);
+                nodemgr_remove_host_dev(&host->device);
+        }
 }
 
 static struct hpsb_highlevel nodemgr_highlevel = {