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tty: hvc: hvc_poll() may sleep

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Introduce points where hvc_poll drops the lock, enables interrupts,
and reschedules.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This commit is contained in:
Nicholas Piggin 2018-05-01 00:55:55 +10:00 committed by Michael Ellerman
parent ec97eaad13
commit cfb5946b55
1 changed files with 14 additions and 2 deletions
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16
drivers/tty/hvc/hvc_console.c
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@ -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