[LinuxPPS] safe pps_register_source()

[Rodolfo Giometti]

Hello,

looking at your patch for old LinuxPPS 4.x series I suppose I need to
apply this patch to the new 5.x series...

Please, let me know what do you think about it.

Thanks,

Rodolfo

---

diff --git a/drivers/pps/kapi.c b/drivers/pps/kapi.c
index ccfa123..46ee3ef 100644
--- a/drivers/pps/kapi.c
+++ b/drivers/pps/kapi.c
@@ -119,6 +119,7 @@ int pps_register_source(struct pps_source_info *info, int default_params)
        pps->info = *info;
 
        init_waitqueue_head(&pps->queue);
+       init_completion(&pps->event_done);
        spin_lock_init(&pps->lock);
 
        /* Create the char device */
@@ -178,6 +179,8 @@ void pps_unregister_source(int source)
        idr_remove(&pps_idr, pps->id);
        spin_unlock_irq(&idr_lock);
 
+       wait_for_completion(&pps->event_done);
+
        pps_sysfs_remove_source_entry(pps);
        pps_unregister_cdev(pps);
        kfree(pps);
@@ -251,5 +254,10 @@ void pps_event(int source, int event, void *data)
        kill_fasync(&pps->async_queue, SIGIO, POLL_IN);
 
        spin_unlock_irqrestore(&pps->lock, flags);
+
+       /* This should be done as the very last command since after it the
+        * PPS source may be removed safely.
+        */
+       complete(&pps->event_done);
 }
 EXPORT_SYMBOL(pps_event);
diff --git a/include/linux/pps.h b/include/linux/pps.h
index a513da9..0d66b83 100644
--- a/include/linux/pps.h
+++ b/include/linux/pps.h
@@ -169,6 +169,7 @@ struct pps_device {
        struct device *dev;
        int devno;
        struct fasync_struct *async_queue;      /* fasync method */
+       struct completion event_done;           /* pps_event() has finished */
        spinlock_t lock;
 
        struct class_device class_dev;


-- 

GNU/Linux Solutions                  e-mail:    giometti at enneenne.com
Linux Device Driver                             giometti at gnudd.com
Embedded Systems                     		giometti at linux.it
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