Hi,
On 4.04.2016 15:57, Michal Nazarewicz wrote:
On Sat, Apr 02 2016, Alan Stern wrote:
On Sat, 2 Apr 2016, Michal Nazarewicz wrote:
Because of all that, I think the best course of action is to just check
whether the thread is running and conditionally start it in fsg_bind,
i.e.:
--- a/drivers/usb/gadget/function/f_mass_storage.c
+++ b/drivers/usb/gadget/function/f_mass_storage.c
@@ -2979,20 +2979,7 @@ EXPORT_SYMBOL_GPL(fsg_common_set_inquiry_string);
int fsg_common_run_thread(struct fsg_common *common)
{
- common->state = FSG_STATE_IDLE;
- /* Tell the thread to start working */
- common->thread_task =
- kthread_create(fsg_main_thread, common, "file-storage");
- if (IS_ERR(common->thread_task)) {
- common->state = FSG_STATE_TERMINATED;
- return PTR_ERR(common->thread_task);
- }
-
- DBG(common, "I/O thread pid: %d\n", task_pid_nr(common->thread_task));
-
- wake_up_process(common->thread_task);
-
- return 0;
+ /* kill this function and all call sites */
}
EXPORT_SYMBOL_GPL(fsg_common_run_thread);
@@ -3005,6 +2992,7 @@ static void fsg_common_release(struct kref *ref)
if (common->state != FSG_STATE_TERMINATED) {
raise_exception(common, FSG_STATE_EXIT);
wait_for_completion(&common->thread_notifier);
+ common->thread_task = NULL;
}
for (i = 0; i < ARRAY_SIZE(common->luns); ++i) {
@@ -3050,9 +3038,21 @@ static int fsg_bind(struct usb_configuration *c, struct usb_function *f)
if (ret)
return ret;
fsg_common_set_inquiry_string(fsg->common, NULL, NULL);
- ret = fsg_common_run_thread(fsg->common);
- if (ret)
+ }
+
+ if (!common->thread_task) {
+ common->state = FSG_STATE_IDLE;
+ common->thread_task =
+ kthread_create(fsg_main_thread, common, "file-storage");
+ if (IS_ERR(common->thread_task)) {
+ int ret = PTR_ERR(common->thread_task);
+ common->thread_task = NULL;
+ common->state = FSG_STATE_TERMINATED;
return ret;
+ }
+ DBG(common, "I/O thread pid: %d\n",
+ task_pid_nr(common->thread_task));
+ wake_up_process(common->thread_task);
}
fsg->gadget = gadget;
This should get rid of all the confusion and just do the right thing.
Who and when is going to destroy the thread if one does
"/sys/bus/platform/drivers/musb-hdrc# echo musb-hdrc.0.auto > unbind"?
Wouldn't some kind of refcounting make sense here?
Regards,
Ivo
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