Since commit 77873803363c "net_dma: mark broken" we no longer pin dma engines active for the network-receive-offload use case. As a result the ->free_chan_resources() that occurs after the driver self-test no longer has a NET_DMA induced ->alloc_chan_resources() to back it up. A late firing irq can lead to ksoftirqd spinning indefinitely due to the tasklet_disable() performed by ->free_chan_resources(). Only ->alloc_chan_resources() can clear this condition in affected kernels. This problem has been present since commit 3e037454bcfa "I/OAT: Add support for MSI and MSI-X" in 2.6.24, but is now exposed. Given the NET_DMA use case is deprecated we can revisit moving the driver to use threaded irqs. For now, just tear down the irq and tasklet properly by: 1/ Disable the irq from triggering the tasklet 2/ Disable the irq from re-arming 3/ Flush inflight interrupts 4/ Flush the timer 5/ Flush inflight tasklets References: https://lkml.org/lkml/2014/1/27/282 https://lkml.org/lkml/2014/2/19/672 Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Cc: Ingo Molnar <mingo@xxxxxxx> Cc: Steven Rostedt <rostedt@xxxxxxxxxxx> Cc: <stable@xxxxxxxxxxxxxxx> Reported-by: Mike Galbraith <bitbucket@xxxxxxxxx> Reported-by: Stanislav Fomichev <stfomichev@xxxxxxxxxxxxxx> Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx> --- Passes my testing, but would appreciate a tested-by. drivers/dma/ioat/dma.c | 52 +++++++++++++++++++++++++++++++++++++++------ drivers/dma/ioat/dma.h | 1 + drivers/dma/ioat/dma_v2.c | 11 ++++------ drivers/dma/ioat/dma_v3.c | 3 +++ 4 files changed, 54 insertions(+), 13 deletions(-) diff --git a/drivers/dma/ioat/dma.c b/drivers/dma/ioat/dma.c index 87529181efcc..4e3549a16132 100644 --- a/drivers/dma/ioat/dma.c +++ b/drivers/dma/ioat/dma.c @@ -77,7 +77,8 @@ static irqreturn_t ioat_dma_do_interrupt(int irq, void *data) attnstatus = readl(instance->reg_base + IOAT_ATTNSTATUS_OFFSET); for_each_set_bit(bit, &attnstatus, BITS_PER_LONG) { chan = ioat_chan_by_index(instance, bit); - tasklet_schedule(&chan->cleanup_task); + if (test_bit(IOAT_RUN, &chan->state)) + tasklet_schedule(&chan->cleanup_task); } writeb(intrctrl, instance->reg_base + IOAT_INTRCTRL_OFFSET); @@ -93,7 +94,8 @@ static irqreturn_t ioat_dma_do_interrupt_msix(int irq, void *data) { struct ioat_chan_common *chan = data; - tasklet_schedule(&chan->cleanup_task); + if (test_bit(IOAT_RUN, &chan->state)) + tasklet_schedule(&chan->cleanup_task); return IRQ_HANDLED; } @@ -116,7 +118,6 @@ void ioat_init_channel(struct ioatdma_device *device, struct ioat_chan_common *c chan->timer.function = device->timer_fn; chan->timer.data = data; tasklet_init(&chan->cleanup_task, device->cleanup_fn, data); - tasklet_disable(&chan->cleanup_task); } /** @@ -354,13 +355,49 @@ static int ioat1_dma_alloc_chan_resources(struct dma_chan *c) writel(((u64) chan->completion_dma) >> 32, chan->reg_base + IOAT_CHANCMP_OFFSET_HIGH); - tasklet_enable(&chan->cleanup_task); + set_bit(IOAT_RUN, &chan->state); ioat1_dma_start_null_desc(ioat); /* give chain to dma device */ dev_dbg(to_dev(chan), "%s: allocated %d descriptors\n", __func__, ioat->desccount); return ioat->desccount; } +void ioat_stop(struct ioat_chan_common *chan) +{ + struct ioatdma_device *device = chan->device; + struct pci_dev *pdev = device->pdev; + int chan_id = chan_num(chan); + struct msix_entry *msix; + + /* 1/ stop irq from firing tasklets + * 2/ stop the tasklet from re-arming irqs + */ + clear_bit(IOAT_RUN, &chan->state); + + /* flush inflight interrupts */ + switch (device->irq_mode) { + case IOAT_MSIX: + msix = &device->msix_entries[chan_id]; + synchronize_irq(msix->vector); + break; + case IOAT_MSI: + case IOAT_INTX: + synchronize_irq(pdev->irq); + break; + default: + break; + } + + /* flush inflight timers */ + del_timer_sync(&chan->timer); + + /* flush inflight tasklet runs */ + tasklet_kill(&chan->cleanup_task); + + /* final cleanup now that everything is quiesced and can't re-arm */ + device->cleanup_fn((unsigned long) &chan->common); +} + /** * ioat1_dma_free_chan_resources - release all the descriptors * @chan: the channel to be cleaned @@ -379,9 +416,7 @@ static void ioat1_dma_free_chan_resources(struct dma_chan *c) if (ioat->desccount == 0) return; - tasklet_disable(&chan->cleanup_task); - del_timer_sync(&chan->timer); - ioat1_cleanup(ioat); + ioat_stop(chan); /* Delay 100ms after reset to allow internal DMA logic to quiesce * before removing DMA descriptor resources. @@ -526,8 +561,11 @@ ioat1_dma_prep_memcpy(struct dma_chan *c, dma_addr_t dma_dest, static void ioat1_cleanup_event(unsigned long data) { struct ioat_dma_chan *ioat = to_ioat_chan((void *) data); + struct ioat_chan_common *chan = &ioat->base; ioat1_cleanup(ioat); + if (!test_bit(IOAT_RUN, &chan->state)) + return; writew(IOAT_CHANCTRL_RUN, ioat->base.reg_base + IOAT_CHANCTRL_OFFSET); } diff --git a/drivers/dma/ioat/dma.h b/drivers/dma/ioat/dma.h index 11fb877ddca9..e982f00a9843 100644 --- a/drivers/dma/ioat/dma.h +++ b/drivers/dma/ioat/dma.h @@ -356,6 +356,7 @@ bool ioat_cleanup_preamble(struct ioat_chan_common *chan, void ioat_kobject_add(struct ioatdma_device *device, struct kobj_type *type); void ioat_kobject_del(struct ioatdma_device *device); int ioat_dma_setup_interrupts(struct ioatdma_device *device); +void ioat_stop(struct ioat_chan_common *chan); extern const struct sysfs_ops ioat_sysfs_ops; extern struct ioat_sysfs_entry ioat_version_attr; extern struct ioat_sysfs_entry ioat_cap_attr; diff --git a/drivers/dma/ioat/dma_v2.c b/drivers/dma/ioat/dma_v2.c index 5d3affe7e976..8d1058085eeb 100644 --- a/drivers/dma/ioat/dma_v2.c +++ b/drivers/dma/ioat/dma_v2.c @@ -190,8 +190,11 @@ static void ioat2_cleanup(struct ioat2_dma_chan *ioat) void ioat2_cleanup_event(unsigned long data) { struct ioat2_dma_chan *ioat = to_ioat2_chan((void *) data); + struct ioat_chan_common *chan = &ioat->base; ioat2_cleanup(ioat); + if (!test_bit(IOAT_RUN, &chan->state)) + return; writew(IOAT_CHANCTRL_RUN, ioat->base.reg_base + IOAT_CHANCTRL_OFFSET); } @@ -553,10 +556,10 @@ int ioat2_alloc_chan_resources(struct dma_chan *c) ioat->issued = 0; ioat->tail = 0; ioat->alloc_order = order; + set_bit(IOAT_RUN, &chan->state); spin_unlock_bh(&ioat->prep_lock); spin_unlock_bh(&chan->cleanup_lock); - tasklet_enable(&chan->cleanup_task); ioat2_start_null_desc(ioat); /* check that we got off the ground */ @@ -566,7 +569,6 @@ int ioat2_alloc_chan_resources(struct dma_chan *c) } while (i++ < 20 && !is_ioat_active(status) && !is_ioat_idle(status)); if (is_ioat_active(status) || is_ioat_idle(status)) { - set_bit(IOAT_RUN, &chan->state); return 1 << ioat->alloc_order; } else { u32 chanerr = readl(chan->reg_base + IOAT_CHANERR_OFFSET); @@ -809,11 +811,8 @@ void ioat2_free_chan_resources(struct dma_chan *c) if (!ioat->ring) return; - tasklet_disable(&chan->cleanup_task); - del_timer_sync(&chan->timer); - device->cleanup_fn((unsigned long) c); + ioat_stop(chan); device->reset_hw(chan); - clear_bit(IOAT_RUN, &chan->state); spin_lock_bh(&chan->cleanup_lock); spin_lock_bh(&ioat->prep_lock); diff --git a/drivers/dma/ioat/dma_v3.c b/drivers/dma/ioat/dma_v3.c index 820817e97e62..b9b38a1cf92f 100644 --- a/drivers/dma/ioat/dma_v3.c +++ b/drivers/dma/ioat/dma_v3.c @@ -464,8 +464,11 @@ static void ioat3_cleanup(struct ioat2_dma_chan *ioat) static void ioat3_cleanup_event(unsigned long data) { struct ioat2_dma_chan *ioat = to_ioat2_chan((void *) data); + struct ioat_chan_common *chan = &ioat->base; ioat3_cleanup(ioat); + if (!test_bit(IOAT_RUN, &chan->state)) + return; writew(IOAT_CHANCTRL_RUN, ioat->base.reg_base + IOAT_CHANCTRL_OFFSET); } -- To unsubscribe from this list: send the line "unsubscribe dmaengine" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
