tty: hvc: use mutex instead of spinlock for hvc_structs lock

This allows hvc operations to sleep under the lock.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

diff --git a/drivers/tty/hvc/hvc_console.c b/drivers/tty/hvc/hvc_console.c
index 7709fcc707f4e62322a0247687b7872d99724060..fddb63322c6786333920cc5c9837d2da5c9cb9bf 100644 (file)
--- a/drivers/tty/hvc/hvc_console.c
+++ b/drivers/tty/hvc/hvc_console.c
@@ -73,7 +73,7 @@ static LIST_HEAD(hvc_structs);
  * Protect the list of hvc_struct instances from inserts and removals during
  * list traversal.
  */
-static DEFINE_SPINLOCK(hvc_structs_lock);
+static DEFINE_MUTEX(hvc_structs_mutex);
 
 /*
  * This value is used to assign a tty->index value to a hvc_struct based
@@ -83,7 +83,7 @@ static DEFINE_SPINLOCK(hvc_structs_lock);
 static int last_hvc = -1;
 
 /*
- * Do not call this function with either the hvc_structs_lock or the hvc_struct
+ * Do not call this function with either the hvc_structs_mutex or the hvc_struct
  * lock held.  If successful, this function increments the kref reference
  * count against the target hvc_struct so it should be released when finished.
  */
@@ -92,25 +92,24 @@ static struct hvc_struct *hvc_get_by_index(int index)
        struct hvc_struct *hp;
        unsigned long flags;
 
-       spin_lock(&hvc_structs_lock);
+       mutex_lock(&hvc_structs_mutex);
 
        list_for_each_entry(hp, &hvc_structs, next) {
                spin_lock_irqsave(&hp->lock, flags);
                if (hp->index == index) {
                        tty_port_get(&hp->port);
                        spin_unlock_irqrestore(&hp->lock, flags);
-                       spin_unlock(&hvc_structs_lock);
+                       mutex_unlock(&hvc_structs_mutex);
                        return hp;
                }
                spin_unlock_irqrestore(&hp->lock, flags);
        }
        hp = NULL;
+       mutex_unlock(&hvc_structs_mutex);
 
-       spin_unlock(&hvc_structs_lock);
        return hp;
 }
 
-
 /*
  * Initial console vtermnos for console API usage prior to full console
  * initialization.  Any vty adapter outside this range will not have usable
@@ -224,13 +223,13 @@ static void hvc_port_destruct(struct tty_port *port)
        struct hvc_struct *hp = container_of(port, struct hvc_struct, port);
        unsigned long flags;
 
-       spin_lock(&hvc_structs_lock);
+       mutex_lock(&hvc_structs_mutex);
 
        spin_lock_irqsave(&hp->lock, flags);
        list_del(&(hp->next));
        spin_unlock_irqrestore(&hp->lock, flags);
 
-       spin_unlock(&hvc_structs_lock);
+       mutex_unlock(&hvc_structs_mutex);
 
        kfree(hp);
 }
@@ -733,11 +732,11 @@ static int khvcd(void *unused)
                try_to_freeze();
                wmb();
                if (!cpus_are_in_xmon()) {
-                       spin_lock(&hvc_structs_lock);
+                       mutex_lock(&hvc_structs_mutex);
                        list_for_each_entry(hp, &hvc_structs, next) {
                                poll_mask |= hvc_poll(hp);
                        }
-                       spin_unlock(&hvc_structs_lock);
+                       mutex_unlock(&hvc_structs_mutex);
                } else
                        poll_mask |= HVC_POLL_READ;
                if (hvc_kicked)
@@ -871,7 +870,7 @@ struct hvc_struct *hvc_alloc(uint32_t vtermno, int data,
 
        INIT_WORK(&hp->tty_resize, hvc_set_winsz);
        spin_lock_init(&hp->lock);
-       spin_lock(&hvc_structs_lock);
+       mutex_lock(&hvc_structs_mutex);
 
        /*
         * find index to use:
@@ -891,7 +890,7 @@ struct hvc_struct *hvc_alloc(uint32_t vtermno, int data,
        vtermnos[i] = vtermno;
 
        list_add_tail(&(hp->next), &hvc_structs);
-       spin_unlock(&hvc_structs_lock);
+       mutex_unlock(&hvc_structs_mutex);
 
        /* check if we need to re-register the kernel console */
        hvc_check_console(i);