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Subject[PATCH 12/15] tty: hvc: hvc_poll may sleep
Date
Introduce points where hvc_poll drops the lock, enables interrupts,
and reschedules.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
drivers/tty/hvc/hvc_console.c | 16 ++++++++++++++--
1 file changed, 14 insertions(+), 2 deletions(-)

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
--
2.17.0
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