From 4dec23d7718e6f1f5e1773698d112025169e7d49 Mon Sep 17 00:00:00 2001 From: Dave Jiang Date: Thu, 7 Feb 2013 14:38:32 -0700 Subject: ioatdma: fix race between updating ioat->head and IOAT_COMPLETION_PENDING There is a race that can hit during __cleanup() when the ioat->head pointer is incremented during descriptor submission. The __cleanup() can clear the PENDING flag when it does not see any active descriptors. This causes new submitted descriptors to be ignored because the COMPLETION_PENDING flag is cleared. This was introduced when code was adapted from ioatdma v1 to ioatdma v2. For v2 and v3, IOAT_COMPLETION_PENDING flag will be abandoned and a new flag IOAT_CHAN_ACTIVE will be utilized. This flag will also be protected under the prep_lock when being modified in order to avoid the race. Signed-off-by: Dave Jiang Reviewed-by: Dan Williams Signed-off-by: Vinod Koul --- drivers/dma/ioat/dma_v2.c | 113 ++++++++++++++++++++++++++-------------------- 1 file changed, 64 insertions(+), 49 deletions(-) (limited to 'drivers/dma/ioat/dma_v2.c') diff --git a/drivers/dma/ioat/dma_v2.c b/drivers/dma/ioat/dma_v2.c index b9d6678..e2b2c70 100644 --- a/drivers/dma/ioat/dma_v2.c +++ b/drivers/dma/ioat/dma_v2.c @@ -269,61 +269,22 @@ static void ioat2_restart_channel(struct ioat2_dma_chan *ioat) __ioat2_restart_chan(ioat); } -void ioat2_timer_event(unsigned long data) +static void check_active(struct ioat2_dma_chan *ioat) { - struct ioat2_dma_chan *ioat = to_ioat2_chan((void *) data); struct ioat_chan_common *chan = &ioat->base; - if (test_bit(IOAT_COMPLETION_PENDING, &chan->state)) { - dma_addr_t phys_complete; - u64 status; - - status = ioat_chansts(chan); - - /* when halted due to errors check for channel - * programming errors before advancing the completion state - */ - if (is_ioat_halted(status)) { - u32 chanerr; - - chanerr = readl(chan->reg_base + IOAT_CHANERR_OFFSET); - dev_err(to_dev(chan), "%s: Channel halted (%x)\n", - __func__, chanerr); - if (test_bit(IOAT_RUN, &chan->state)) - BUG_ON(is_ioat_bug(chanerr)); - else /* we never got off the ground */ - return; - } - - /* if we haven't made progress and we have already - * acknowledged a pending completion once, then be more - * forceful with a restart - */ - spin_lock_bh(&chan->cleanup_lock); - if (ioat_cleanup_preamble(chan, &phys_complete)) { - __cleanup(ioat, phys_complete); - } else if (test_bit(IOAT_COMPLETION_ACK, &chan->state)) { - spin_lock_bh(&ioat->prep_lock); - ioat2_restart_channel(ioat); - spin_unlock_bh(&ioat->prep_lock); - } else { - set_bit(IOAT_COMPLETION_ACK, &chan->state); - mod_timer(&chan->timer, jiffies + COMPLETION_TIMEOUT); - } - spin_unlock_bh(&chan->cleanup_lock); - } else { - u16 active; + if (ioat2_ring_active(ioat)) { + mod_timer(&chan->timer, jiffies + COMPLETION_TIMEOUT); + return; + } + if (test_and_clear_bit(IOAT_CHAN_ACTIVE, &chan->state)) + mod_timer(&chan->timer, jiffies + IDLE_TIMEOUT); + else if (ioat->alloc_order > ioat_get_alloc_order()) { /* if the ring is idle, empty, and oversized try to step * down the size */ - spin_lock_bh(&chan->cleanup_lock); - spin_lock_bh(&ioat->prep_lock); - active = ioat2_ring_active(ioat); - if (active == 0 && ioat->alloc_order > ioat_get_alloc_order()) - reshape_ring(ioat, ioat->alloc_order-1); - spin_unlock_bh(&ioat->prep_lock); - spin_unlock_bh(&chan->cleanup_lock); + reshape_ring(ioat, ioat->alloc_order - 1); /* keep shrinking until we get back to our minimum * default size @@ -331,6 +292,60 @@ void ioat2_timer_event(unsigned long data) if (ioat->alloc_order > ioat_get_alloc_order()) mod_timer(&chan->timer, jiffies + IDLE_TIMEOUT); } + +} + +void ioat2_timer_event(unsigned long data) +{ + struct ioat2_dma_chan *ioat = to_ioat2_chan((void *) data); + struct ioat_chan_common *chan = &ioat->base; + dma_addr_t phys_complete; + u64 status; + + status = ioat_chansts(chan); + + /* when halted due to errors check for channel + * programming errors before advancing the completion state + */ + if (is_ioat_halted(status)) { + u32 chanerr; + + chanerr = readl(chan->reg_base + IOAT_CHANERR_OFFSET); + dev_err(to_dev(chan), "%s: Channel halted (%x)\n", + __func__, chanerr); + if (test_bit(IOAT_RUN, &chan->state)) + BUG_ON(is_ioat_bug(chanerr)); + else /* we never got off the ground */ + return; + } + + /* if we haven't made progress and we have already + * acknowledged a pending completion once, then be more + * forceful with a restart + */ + spin_lock_bh(&chan->cleanup_lock); + if (ioat_cleanup_preamble(chan, &phys_complete)) + __cleanup(ioat, phys_complete); + else if (test_bit(IOAT_COMPLETION_ACK, &chan->state)) { + spin_lock_bh(&ioat->prep_lock); + ioat2_restart_channel(ioat); + spin_unlock_bh(&ioat->prep_lock); + spin_unlock_bh(&chan->cleanup_lock); + return; + } else { + set_bit(IOAT_COMPLETION_ACK, &chan->state); + mod_timer(&chan->timer, jiffies + COMPLETION_TIMEOUT); + } + + + if (ioat2_ring_active(ioat)) + mod_timer(&chan->timer, jiffies + COMPLETION_TIMEOUT); + else { + spin_lock_bh(&ioat->prep_lock); + check_active(ioat); + spin_unlock_bh(&ioat->prep_lock); + } + spin_unlock_bh(&chan->cleanup_lock); } static int ioat2_reset_hw(struct ioat_chan_common *chan) @@ -404,7 +419,7 @@ static dma_cookie_t ioat2_tx_submit_unlock(struct dma_async_tx_descriptor *tx) cookie = dma_cookie_assign(tx); dev_dbg(to_dev(&ioat->base), "%s: cookie: %d\n", __func__, cookie); - if (!test_and_set_bit(IOAT_COMPLETION_PENDING, &chan->state)) + if (!test_and_set_bit(IOAT_CHAN_ACTIVE, &chan->state)) mod_timer(&chan->timer, jiffies + COMPLETION_TIMEOUT); /* make descriptor updates visible before advancing ioat->head, -- cgit v1.1