[PATCH] USB: File-Storage gadget: use the kthread API

This patch (as566) converts the File-Storage gadget over to the kthread
API.  The new code doesn't use kthread_stop because the control thread
needs to terminate asynchronously when it receives a signal.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

 drivers/usb/gadget/file_storage.c |   32 +++++++++++++-------------------
 1 file changed, 13 insertions(+), 19 deletions(-)

1 files changed, 13 insertions, 19 deletions

diff --git a/drivers/usb/gadget/file_storage.c b/drivers/usb/gadget/file_storage.c
index a41d9d4baee3..241c570e541c 100644
--- a/drivers/usb/gadget/file_storage.c
+++ b/drivers/usb/gadget/file_storage.c
@@ -224,6 +224,7 @@
 #include <linux/fs.h>
 #include <linux/init.h>
 #include <linux/kernel.h>
+#include <linux/kthread.h>
 #include <linux/limits.h>
 #include <linux/list.h>
 #include <linux/module.h>
@@ -669,7 +670,6 @@ struct fsg_dev {
         wait_queue_head_t       thread_wqh;
         int                     thread_wakeup_needed;
         struct completion       thread_notifier;
-        int                     thread_pid;
         struct task_struct      *thread_task;
         sigset_t                thread_signal_mask;
 
@@ -1084,7 +1084,6 @@ static void wakeup_thread(struct fsg_dev *fsg)
 static void raise_exception(struct fsg_dev *fsg, enum fsg_state new_state)
 {
         unsigned long           flags;
-        struct task_struct      *thread_task;
 
         /* Do nothing if a higher-priority exception is already in progress.
          * If a lower-or-equal priority exception is in progress, preempt it
@@ -1093,9 +1092,9 @@ static void raise_exception(struct fsg_dev *fsg, enum fsg_state new_state)
         if (fsg->state <= new_state) {
                 fsg->exception_req_tag = fsg->ep0_req_tag;
                 fsg->state = new_state;
-                thread_task = fsg->thread_task;
-                if (thread_task)
-                        send_sig_info(SIGUSR1, SEND_SIG_FORCED, thread_task);
+                if (fsg->thread_task)
+                        send_sig_info(SIGUSR1, SEND_SIG_FORCED,
+                                        fsg->thread_task);
         }
         spin_unlock_irqrestore(&fsg->lock, flags);
 }
@@ -3383,11 +3382,6 @@ static int fsg_main_thread(void *fsg_)
 {
         struct fsg_dev          *fsg = (struct fsg_dev *) fsg_;
 
-        fsg->thread_task = current;
-
-        /* Release all our userspace resources */
-        daemonize("file-storage-gadget");
-
         /* Allow the thread to be killed by a signal, but set the signal mask
          * to block everything but INT, TERM, KILL, and USR1. */
         siginitsetinv(&fsg->thread_signal_mask, sigmask(SIGINT) |
@@ -3400,9 +3394,6 @@ static int fsg_main_thread(void *fsg_)
          * that expects a __user pointer and it will work okay. */
         set_fs(get_ds());
 
-        /* Wait for the gadget registration to finish up */
-        wait_for_completion(&fsg->thread_notifier);
-
         /* The main loop */
         while (fsg->state != FSG_STATE_TERMINATED) {
                 if (exception_in_progress(fsg) || signal_pending(current)) {
@@ -3440,8 +3431,9 @@ static int fsg_main_thread(void *fsg_)
                 spin_unlock_irq(&fsg->lock);
                 }
 
+        spin_lock_irq(&fsg->lock);
         fsg->thread_task = NULL;
-        flush_signals(current);
+        spin_unlock_irq(&fsg->lock);
 
         /* In case we are exiting because of a signal, unregister the
          * gadget driver and close the backing file. */
@@ -3959,10 +3951,12 @@ static int __init fsg_bind(struct usb_gadget *gadget)
                 sprintf(&serial[i], "%02X", c);
         }
 
-        if ((rc = kernel_thread(fsg_main_thread, fsg, (CLONE_VM | CLONE_FS |
-                        CLONE_FILES))) < 0)
+        fsg->thread_task = kthread_create(fsg_main_thread, fsg,
+                        "file-storage-gadget");
+        if (IS_ERR(fsg->thread_task)) {
+                rc = PTR_ERR(fsg->thread_task);
                 goto out;
-        fsg->thread_pid = rc;
+        }
 
         INFO(fsg, DRIVER_DESC ", version: " DRIVER_VERSION "\n");
         INFO(fsg, "Number of LUNs=%d\n", fsg->nluns);
@@ -3994,7 +3988,7 @@ static int __init fsg_bind(struct usb_gadget *gadget)
         DBG(fsg, "removable=%d, stall=%d, buflen=%u\n",
                         mod_data.removable, mod_data.can_stall,
                         mod_data.buflen);
-        DBG(fsg, "I/O thread pid: %d\n", fsg->thread_pid);
+        DBG(fsg, "I/O thread pid: %d\n", fsg->thread_task->pid);
         return 0;
 
 autoconf_fail:
@@ -4093,7 +4087,7 @@ static int __init fsg_init(void)
         set_bit(REGISTERED, &fsg->atomic_bitflags);
 
         /* Tell the thread to start working */
-        complete(&fsg->thread_notifier);
+        wake_up_process(fsg->thread_task);
         return 0;
 }
 module_init(fsg_init);