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authorLinus Torvalds <torvalds@linux-foundation.org>2009-10-14 08:59:49 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2009-10-14 08:59:49 -0700
commit45242006e19c6f99945554e4d7d5680caf6ed9ad (patch)
tree7b3561169050d242469df55ed338e752c9a35c48 /drivers/char
parent80f506918fdaaca6b574ba931536a58ce015c7be (diff)
Make flush_to_ldisc properly handle parallel calls
Diffstat (limited to 'drivers/char')
-rw-r--r--drivers/char/tty_buffer.c29
1 files changed, 13 insertions, 16 deletions
diff --git a/drivers/char/tty_buffer.c b/drivers/char/tty_buffer.c
index 3108991c5c8..0296612cc7d 100644
--- a/drivers/char/tty_buffer.c
+++ b/drivers/char/tty_buffer.c
@@ -402,28 +402,26 @@ static void flush_to_ldisc(struct work_struct *work)
container_of(work, struct tty_struct, buf.work.work);
unsigned long flags;
struct tty_ldisc *disc;
- struct tty_buffer *tbuf, *head;
- char *char_buf;
- unsigned char *flag_buf;
disc = tty_ldisc_ref(tty);
if (disc == NULL) /* !TTY_LDISC */
return;
spin_lock_irqsave(&tty->buf.lock, flags);
- /* So we know a flush is running */
- set_bit(TTY_FLUSHING, &tty->flags);
- head = tty->buf.head;
- if (head != NULL) {
- tty->buf.head = NULL;
- for (;;) {
- int count = head->commit - head->read;
+
+ if (!test_and_set_bit(TTY_FLUSHING, &tty->flags)) {
+ struct tty_buffer *head;
+ while ((head = tty->buf.head) != NULL) {
+ int count;
+ char *char_buf;
+ unsigned char *flag_buf;
+
+ count = head->commit - head->read;
if (!count) {
if (head->next == NULL)
break;
- tbuf = head;
- head = head->next;
- tty_buffer_free(tty, tbuf);
+ tty->buf.head = head->next;
+ tty_buffer_free(tty, head);
continue;
}
/* Ldisc or user is trying to flush the buffers
@@ -445,9 +443,9 @@ static void flush_to_ldisc(struct work_struct *work)
flag_buf, count);
spin_lock_irqsave(&tty->buf.lock, flags);
}
- /* Restore the queue head */
- tty->buf.head = head;
+ clear_bit(TTY_FLUSHING, &tty->flags);
}
+
/* We may have a deferred request to flush the input buffer,
if so pull the chain under the lock and empty the queue */
if (test_bit(TTY_FLUSHPENDING, &tty->flags)) {
@@ -455,7 +453,6 @@ static void flush_to_ldisc(struct work_struct *work)
clear_bit(TTY_FLUSHPENDING, &tty->flags);
wake_up(&tty->read_wait);
}
- clear_bit(TTY_FLUSHING, &tty->flags);
spin_unlock_irqrestore(&tty->buf.lock, flags);
tty_ldisc_deref(disc);