diff options
| author | Michal Ostrowski <mostrows@watson.ibm.com> | 2006-02-18 09:29:59 -0500 |
|---|---|---|
| committer | Paul Mackerras <paulus@samba.org> | 2006-02-24 11:36:40 +1100 |
| commit | fb5c594c2acc441f0d2d8f457484a0e0e9285db3 (patch) | |
| tree | 0465b7b5fb518f21f6d4689e027f0f04bb3ebe35 /drivers/char | |
| parent | 4558f417f49595337b7e9cc3e92bc0856c588ac1 (diff) | |
[PATCH] Fix race condition in hvc console.
tty_schedule_flip() would schedule a thread that would call flush_to_ldisc().
If tty_buffer_request_room() gets called prior to that thread running --
which is likely in this loop in hvc_poll(), it would set the active flag
in the tty buffer and consequently flush_to_ldisc() would ignore it.
The result is that input on the hvc console is not processed.
This fix calls tty_flip_buffer_push (and flags the tty as
"low_latency"). The push to the ldisc thus happens synchronously.
Signed-off-by: Michal Ostrowski <mostrows@watson.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>
Diffstat (limited to 'drivers/char')
| -rw-r--r-- | drivers/char/hvc_console.c | 8 |
1 files changed, 5 insertions, 3 deletions
diff --git a/drivers/char/hvc_console.c b/drivers/char/hvc_console.c index 1994a92d473..f65b2e14a48 100644 --- a/drivers/char/hvc_console.c +++ b/drivers/char/hvc_console.c @@ -335,6 +335,8 @@ static int hvc_open(struct tty_struct *tty, struct file * filp) } /* else count == 0 */ tty->driver_data = hp; + tty->low_latency = 1; /* Makes flushes to ldisc synchronous. */ + hp->tty = tty; /* Save for request_irq outside of spin_lock. */ irq = hp->irq; @@ -633,9 +635,6 @@ static int hvc_poll(struct hvc_struct *hp) tty_insert_flip_char(tty, buf[i], 0); } - if (count) - tty_schedule_flip(tty); - /* * Account for the total amount read in one loop, and if above * 64 bytes, we do a quick schedule loop to let the tty grok @@ -656,6 +655,9 @@ static int hvc_poll(struct hvc_struct *hp) bail: spin_unlock_irqrestore(&hp->lock, flags); + if (read_total) + tty_flip_buffer_push(tty); + return poll_mask; } |