From cfb5946b55f1dfd19e042feae1fbff6041e25a98 Mon Sep 17 00:00:00 2001 From: Nicholas Piggin Date: Tue, 1 May 2018 00:55:55 +1000 Subject: tty: hvc: hvc_poll() may sleep Introduce points where hvc_poll drops the lock, enables interrupts, and reschedules. Signed-off-by: Nicholas Piggin Signed-off-by: Michael Ellerman --- drivers/tty/hvc/hvc_console.c | 16 ++++++++++++++-- 1 file changed, 14 insertions(+), 2 deletions(-) (limited to 'drivers/tty') diff --git a/drivers/tty/hvc/hvc_console.c b/drivers/tty/hvc/hvc_console.c index 745ac220fce8..2abfc0b15fbb 100644 --- a/drivers/tty/hvc/hvc_console.c +++ b/drivers/tty/hvc/hvc_console.c @@ -589,7 +589,7 @@ static u32 timeout = MIN_TIMEOUT; #define HVC_POLL_READ 0x00000001 #define HVC_POLL_WRITE 0x00000002 -int hvc_poll(struct hvc_struct *hp) +static int __hvc_poll(struct hvc_struct *hp, bool may_sleep) { struct tty_struct *tty; int i, n, count, poll_mask = 0; @@ -611,6 +611,12 @@ int hvc_poll(struct hvc_struct *hp) timeout = (written_total) ? 0 : MIN_TIMEOUT; } + if (may_sleep) { + spin_unlock_irqrestore(&hp->lock, flags); + cond_resched(); + spin_lock_irqsave(&hp->lock, flags); + } + /* No tty attached, just skip */ tty = tty_port_tty_get(&hp->port); if (tty == NULL) @@ -698,6 +704,11 @@ int hvc_poll(struct hvc_struct *hp) return poll_mask; } + +int hvc_poll(struct hvc_struct *hp) +{ + return __hvc_poll(hp, false); +} EXPORT_SYMBOL_GPL(hvc_poll); /** @@ -736,7 +747,8 @@ static int khvcd(void *unused) if (!cpus_are_in_xmon()) { mutex_lock(&hvc_structs_mutex); list_for_each_entry(hp, &hvc_structs, next) { - poll_mask |= hvc_poll(hp); + poll_mask |= __hvc_poll(hp, true); + cond_resched(); } mutex_unlock(&hvc_structs_mutex); } else -- cgit v1.2.3