From: Muhammad Hamza Farooq <[email protected]> The wake up method is called with the port lock held. The st_int_write method calls port->ops->write with tries to acquire the lock again, causing CPU to wait infinitely. Right way to do is to write data to port in worker thread.
Signed-off-by: Muhammad Hamza Farooq <[email protected]> Signed-off-by: Jacob Siverskog <[email protected]> --- drivers/misc/ti-st/st_core.c | 18 ++++++++++++++++-- include/linux/ti_wilink_st.h | 1 + 2 files changed, 17 insertions(+), 2 deletions(-) diff --git a/drivers/misc/ti-st/st_core.c b/drivers/misc/ti-st/st_core.c index c8c6a36..6e3af8b 100644 --- a/drivers/misc/ti-st/st_core.c +++ b/drivers/misc/ti-st/st_core.c @@ -460,6 +460,13 @@ static void st_int_enqueue(struct st_data_s *st_gdata, struct sk_buff *skb) * - TTY layer when write's finished * - st_write (in context of the protocol stack) */ +static void work_fn_write_wakeup(struct work_struct *work) +{ + struct st_data_s *st_gdata = container_of(work, struct st_data_s, + work_write_wakeup); + + st_tx_wakeup((void *)st_gdata); +} void st_tx_wakeup(struct st_data_s *st_data) { struct sk_buff *skb; @@ -812,8 +819,12 @@ static void st_tty_wakeup(struct tty_struct *tty) /* don't do an wakeup for now */ clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags); - /* call our internal wakeup */ - st_tx_wakeup((void *)st_gdata); + /* + * schedule the internal wakeup instead of calling directly to + * avoid lockup (port->lock needed in tty->ops->write is + * already taken here + */ + schedule_work(&st_gdata->work_write_wakeup); } static void st_tty_flush_buffer(struct tty_struct *tty) @@ -881,6 +892,9 @@ int st_core_init(struct st_data_s **core_data) pr_err("unable to un-register ldisc"); return err; } + + INIT_WORK(&st_gdata->work_write_wakeup, work_fn_write_wakeup); + *core_data = st_gdata; return 0; } diff --git a/include/linux/ti_wilink_st.h b/include/linux/ti_wilink_st.h index c78dcfe..9b366ee 100644 --- a/include/linux/ti_wilink_st.h +++ b/include/linux/ti_wilink_st.h @@ -158,6 +158,7 @@ struct st_data_s { unsigned long ll_state; void *kim_data; struct tty_struct *tty; + struct work_struct work_write_wakeup; }; /* -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
