[PATCH] PATCH: usb-storage: use kthread API

This patch is originally from Alan Stern (as569).  It has been rediffed
against a current tree.

This patch converts usb-storage to use the kthread API for creating its
control and scanning threads.  The new code doesn't use kthread_stop
because the threads need (or will need in the future) to exit
asynchronously.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Matthew Dharm <mdharm-usb@one-eyed-alien.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

2 files changed, 21 insertions, 45 deletions

diff --git a/drivers/usb/storage/usb.c b/drivers/usb/storage/usb.c
index c1a902691bc6..3847ebed2aa4 100644
--- a/drivers/usb/storage/usb.c
+++ b/drivers/usb/storage/usb.c
@@ -54,6 +54,7 @@
 #include <linux/module.h>
 #include <linux/init.h>
 #include <linux/slab.h>
+#include <linux/kthread.h>
 
 #include <scsi/scsi.h>
 #include <scsi/scsi_cmnd.h>
@@ -310,22 +311,7 @@ static int usb_stor_control_thread(void * __us)
         struct us_data *us = (struct us_data *)__us;
         struct Scsi_Host *host = us_to_host(us);
 
-        lock_kernel();
-
-        /*
-         * This thread doesn't need any user-level access,
-         * so get rid of all our resources.
-         */
-        daemonize("usb-storage");
         current->flags |= PF_NOFREEZE;
-        unlock_kernel();
-
-        /* acquire a reference to the host, so it won't be deallocated
-         * until we're ready to exit */
-        scsi_host_get(host);
-
-        /* signal that we've started the thread */
-        complete(&(us->notify));
 
         for(;;) {
                 US_DEBUGP("*** thread sleeping.\n");
@@ -768,6 +754,7 @@ static int get_pipes(struct us_data *us)
 static int usb_stor_acquire_resources(struct us_data *us)
 {
         int p;
+        struct task_struct *th;
 
         us->current_urb = usb_alloc_urb(0, GFP_KERNEL);
         if (!us->current_urb) {
@@ -784,17 +771,19 @@ static int usb_stor_acquire_resources(struct us_data *us)
         }
 
         /* Start up our control thread */
-        p = kernel_thread(usb_stor_control_thread, us, CLONE_VM);
-        if (p < 0) {
+        th = kthread_create(usb_stor_control_thread, us, "usb-storage");
+        if (IS_ERR(th)) {
                 printk(KERN_WARNING USB_STORAGE 
                        "Unable to start control thread\n");
-                return p;
+                return PTR_ERR(th);
         }
-        us->pid = p;
-        atomic_inc(&total_threads);
 
-        /* Wait for the thread to start */
-        wait_for_completion(&(us->notify));
+        /* Take a reference to the host for the control thread and
+         * count it among all the threads we have launched.  Then
+         * start it up. */
+        scsi_host_get(us_to_host(us));
+        atomic_inc(&total_threads);
+        wake_up_process(th);
 
         return 0;
 }
@@ -890,21 +879,6 @@ static int usb_stor_scan_thread(void * __us)
 {
         struct us_data *us = (struct us_data *)__us;
 
-        /*
-         * This thread doesn't need any user-level access,
-         * so get rid of all our resources.
-         */
-        lock_kernel();
-        daemonize("usb-stor-scan");
-        unlock_kernel();
-
-        /* Acquire a reference to the host, so it won't be deallocated
-         * until we're ready to exit */
-        scsi_host_get(us_to_host(us));
-
-        /* Signal that we've started the thread */
-        complete(&(us->notify));
-
         printk(KERN_DEBUG
                 "usb-storage: device found at %d\n", us->pusb_dev->devnum);
 
@@ -949,6 +923,7 @@ static int storage_probe(struct usb_interface *intf,
         struct us_data *us;
         const int id_index = id - storage_usb_ids; 
         int result;
+        struct task_struct *th;
 
         US_DEBUGP("USB Mass Storage device detected\n");
 
@@ -1029,17 +1004,21 @@ static int storage_probe(struct usb_interface *intf,
         }
 
         /* Start up the thread for delayed SCSI-device scanning */
-        result = kernel_thread(usb_stor_scan_thread, us, CLONE_VM);
-        if (result < 0) {
+        th = kthread_create(usb_stor_scan_thread, us, "usb-stor-scan");
+        if (IS_ERR(th)) {
                 printk(KERN_WARNING USB_STORAGE 
                        "Unable to start the device-scanning thread\n");
                 quiesce_and_remove_host(us);
+                result = PTR_ERR(th);
                 goto BadDevice;
         }
-        atomic_inc(&total_threads);
 
-        /* Wait for the thread to start */
-        wait_for_completion(&(us->notify));
+        /* Take a reference to the host for the scanning thread and
+         * count it among all the threads we have launched.  Then
+         * start it up. */
+        scsi_host_get(us_to_host(us));
+        atomic_inc(&total_threads);
+        wake_up_process(th);
 
         return 0;
 
diff --git a/drivers/usb/storage/usb.h b/drivers/usb/storage/usb.h
index dfa4dc71dd3e..98b09711a739 100644
--- a/drivers/usb/storage/usb.h
+++ b/drivers/usb/storage/usb.h
@@ -161,9 +161,6 @@ struct us_data {
         struct scsi_cmnd        *srb;            /* current srb         */
         unsigned int            tag;             /* current dCBWTag     */
 
-        /* thread information */
-        int                     pid;             /* control thread       */
-
         /* control and bulk communications data */
         struct urb              *current_urb;    /* USB requests         */
         struct usb_ctrlrequest  *cr;             /* control requests     */