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ioat: fix tasklet tear down 

Since commit 7787380336 "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 3e037454bc "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: Ingo Molnar <mingo@elte.hu>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: <stable@vger.kernel.org>
Reported-by: Mike Galbraith <bitbucket@online.de>
Reported-by: Stanislav Fomichev <stfomichev@yandex-team.ru>
Tested-by: Mike Galbraith <bitbucket@online.de>
Tested-by: Stanislav Fomichev <stfomichev@yandex-team.ru>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
This commit is contained in:
Dan Williams 2014-02-19 16:19:35 -08:00
parent 6d0abeca32
commit da87ca4d4c
4 changed files with 54 additions and 13 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

52
drivers/dma/ioat/dma.c
View File

@ -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);
}

1
drivers/dma/ioat/dma.h
View File

@ -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;

11
drivers/dma/ioat/dma_v2.c
View File

@ -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);

3
drivers/dma/ioat/dma_v3.c
View File

@ -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);
}