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author | Benjamin Herrenschmidt <benh@kernel.crashing.org> | 2012-04-18 22:16:48 +0000 |
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committer | Benjamin Herrenschmidt <benh@kernel.crashing.org> | 2012-04-23 11:04:28 +1000 |
commit | 3027691e58bfb21f6ea2e9f1d225d11b4e2b20e2 (patch) | |
tree | 4ff705ce7b3b9b51563777b584d90cf4d0b1a348 /arch/powerpc/platforms/powermac/low_i2c.c | |
parent | 2ef822c55371b20548d4f58193c580407a5d738d (diff) | |
download | op-kernel-dev-3027691e58bfb21f6ea2e9f1d225d11b4e2b20e2.zip op-kernel-dev-3027691e58bfb21f6ea2e9f1d225d11b4e2b20e2.tar.gz |
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: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Diffstat (limited to 'arch/powerpc/platforms/powermac/low_i2c.c')
-rw-r--r-- | arch/powerpc/platforms/powermac/low_i2c.c | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/arch/powerpc/platforms/powermac/low_i2c.c b/arch/powerpc/platforms/powermac/low_i2c.c index 996c5ff..03685a3 100644 --- a/arch/powerpc/platforms/powermac/low_i2c.c +++ b/arch/powerpc/platforms/powermac/low_i2c.c @@ -366,11 +366,20 @@ static void kw_i2c_timeout(unsigned long data) unsigned long 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)); if (host->state != state_idle) { host->timeout_timer.expires = jiffies + KW_POLL_TIMEOUT; add_timer(&host->timeout_timer); } + skip: spin_unlock_irqrestore(&host->lock, flags); } |