powerpc/pmac: Don't add_timer() twice

If the interrupt and the timeout happen roughly at the same
time, we can get into a situation where the timer function
is run while the interrupt has already been processed. In
this case, the timer function might end up doing an add_timer
on an already pending timer, causing a BUG_ON() to trigger.

Instead, just skip the whole timeout operation if we see that
the timer is pending. The spinlock ensures that the only way
that happens is if we already started a new operation and thus
the timeout can be ignored.
Signed-off-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
parent 2ef822c5
...@@ -366,11 +366,20 @@ static void kw_i2c_timeout(unsigned long data) ...@@ -366,11 +366,20 @@ static void kw_i2c_timeout(unsigned long data)
unsigned long flags; unsigned long flags;
spin_lock_irqsave(&host->lock, flags); spin_lock_irqsave(&host->lock, flags);
/*
* If the timer is pending, that means we raced with the
* irq, in which case we just return
*/
if (timer_pending(&host->timeout_timer))
goto skip;
kw_i2c_handle_interrupt(host, kw_read_reg(reg_isr)); kw_i2c_handle_interrupt(host, kw_read_reg(reg_isr));
if (host->state != state_idle) { if (host->state != state_idle) {
host->timeout_timer.expires = jiffies + KW_POLL_TIMEOUT; host->timeout_timer.expires = jiffies + KW_POLL_TIMEOUT;
add_timer(&host->timeout_timer); add_timer(&host->timeout_timer);
} }
skip:
spin_unlock_irqrestore(&host->lock, flags); spin_unlock_irqrestore(&host->lock, flags);
} }
......
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