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path: root/drivers/char/tty_ldisc.c
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Diffstat (limited to 'drivers/char/tty_ldisc.c')
-rw-r--r--drivers/char/tty_ldisc.c82
1 files changed, 42 insertions, 40 deletions
diff --git a/drivers/char/tty_ldisc.c b/drivers/char/tty_ldisc.c
index e48af9f7921..aafdbaebc16 100644
--- a/drivers/char/tty_ldisc.c
+++ b/drivers/char/tty_ldisc.c
@@ -145,48 +145,33 @@ int tty_unregister_ldisc(int disc)
}
EXPORT_SYMBOL(tty_unregister_ldisc);
-
-/**
- * tty_ldisc_try_get - try and reference an ldisc
- * @disc: ldisc number
- *
- * Attempt to open and lock a line discipline into place. Return
- * the line discipline refcounted or an error.
- */
-
-static struct tty_ldisc *tty_ldisc_try_get(int disc)
+static struct tty_ldisc_ops *get_ldops(int disc)
{
unsigned long flags;
- struct tty_ldisc *ld;
- struct tty_ldisc_ops *ldops;
- int err = -EINVAL;
-
- ld = kmalloc(sizeof(struct tty_ldisc), GFP_KERNEL);
- if (ld == NULL)
- return ERR_PTR(-ENOMEM);
+ struct tty_ldisc_ops *ldops, *ret;
spin_lock_irqsave(&tty_ldisc_lock, flags);
- ld->ops = NULL;
+ ret = ERR_PTR(-EINVAL);
ldops = tty_ldiscs[disc];
- /* Check the entry is defined */
if (ldops) {
- /* If the module is being unloaded we can't use it */
- if (!try_module_get(ldops->owner))
- err = -EAGAIN;
- else {
- /* lock it */
+ ret = ERR_PTR(-EAGAIN);
+ if (try_module_get(ldops->owner)) {
ldops->refcount++;
- ld->ops = ldops;
- atomic_set(&ld->users, 1);
- err = 0;
+ ret = ldops;
}
}
spin_unlock_irqrestore(&tty_ldisc_lock, flags);
- if (err) {
- kfree(ld);
- return ERR_PTR(err);
- }
- return ld;
+ return ret;
+}
+
+static void put_ldops(struct tty_ldisc_ops *ldops)
+{
+ unsigned long flags;
+
+ spin_lock_irqsave(&tty_ldisc_lock, flags);
+ ldops->refcount--;
+ module_put(ldops->owner);
+ spin_unlock_irqrestore(&tty_ldisc_lock, flags);
}
/**
@@ -205,14 +190,31 @@ static struct tty_ldisc *tty_ldisc_try_get(int disc)
static struct tty_ldisc *tty_ldisc_get(int disc)
{
struct tty_ldisc *ld;
+ struct tty_ldisc_ops *ldops;
if (disc < N_TTY || disc >= NR_LDISCS)
return ERR_PTR(-EINVAL);
- ld = tty_ldisc_try_get(disc);
- if (IS_ERR(ld)) {
+
+ /*
+ * Get the ldisc ops - we may need to request them to be loaded
+ * dynamically and try again.
+ */
+ ldops = get_ldops(disc);
+ if (IS_ERR(ldops)) {
request_module("tty-ldisc-%d", disc);
- ld = tty_ldisc_try_get(disc);
+ ldops = get_ldops(disc);
+ if (IS_ERR(ldops))
+ return ERR_CAST(ldops);
}
+
+ ld = kmalloc(sizeof(struct tty_ldisc), GFP_KERNEL);
+ if (ld == NULL) {
+ put_ldops(ldops);
+ return ERR_PTR(-ENOMEM);
+ }
+
+ ld->ops = ldops;
+ atomic_set(&ld->users, 1);
return ld;
}
@@ -234,13 +236,13 @@ static void tty_ldiscs_seq_stop(struct seq_file *m, void *v)
static int tty_ldiscs_seq_show(struct seq_file *m, void *v)
{
int i = *(loff_t *)v;
- struct tty_ldisc *ld;
+ struct tty_ldisc_ops *ldops;
- ld = tty_ldisc_try_get(i);
- if (IS_ERR(ld))
+ ldops = get_ldops(i);
+ if (IS_ERR(ldops))
return 0;
- seq_printf(m, "%-10s %2d\n", ld->ops->name ? ld->ops->name : "???", i);
- put_ldisc(ld);
+ seq_printf(m, "%-10s %2d\n", ldops->name ? ldops->name : "???", i);
+ put_ldops(ldops);
return 0;
}