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Subject[PATCH 11/16] thunderbolt: Use spinlock in ring serialization
Date
This makes it possible to enqueue frames also from atomic context which
is needed for example, when networking packets are sent over a
Thunderbolt cable.

Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Reviewed-by: Michael Jamet <michael.jamet@intel.com>
Reviewed-by: Yehezkel Bernat <yehezkel.bernat@intel.com>
---
drivers/thunderbolt/nhi.c | 26 ++++++++++++++------------
include/linux/thunderbolt.h | 2 +-
2 files changed, 15 insertions(+), 13 deletions(-)

diff --git a/drivers/thunderbolt/nhi.c b/drivers/thunderbolt/nhi.c
index 4704ccd20c84..d1ad37c6eccf 100644
--- a/drivers/thunderbolt/nhi.c
+++ b/drivers/thunderbolt/nhi.c
@@ -212,8 +212,10 @@ static void ring_work(struct work_struct *work)
struct tb_ring *ring = container_of(work, typeof(*ring), work);
struct ring_frame *frame;
bool canceled = false;
+ unsigned long flags;
LIST_HEAD(done);
- mutex_lock(&ring->lock);
+
+ spin_lock_irqsave(&ring->lock, flags);

if (!ring->running) {
/* Move all frames to done and mark them as canceled. */
@@ -241,7 +243,8 @@ static void ring_work(struct work_struct *work)
ring_write_descriptors(ring);

invoke_callback:
- mutex_unlock(&ring->lock); /* allow callbacks to schedule new work */
+ /* allow callbacks to schedule new work */
+ spin_unlock_irqrestore(&ring->lock, flags);
while (!list_empty(&done)) {
frame = list_first_entry(&done, typeof(*frame), list);
/*
@@ -255,15 +258,17 @@ static void ring_work(struct work_struct *work)

int __tb_ring_enqueue(struct tb_ring *ring, struct ring_frame *frame)
{
+ unsigned long flags;
int ret = 0;
- mutex_lock(&ring->lock);
+
+ spin_lock_irqsave(&ring->lock, flags);
if (ring->running) {
list_add_tail(&frame->list, &ring->queue);
ring_write_descriptors(ring);
} else {
ret = -ESHUTDOWN;
}
- mutex_unlock(&ring->lock);
+ spin_unlock_irqrestore(&ring->lock, flags);
return ret;
}
EXPORT_SYMBOL_GPL(__tb_ring_enqueue);
@@ -338,7 +343,7 @@ static struct tb_ring *tb_ring_alloc(struct tb_nhi *nhi, u32 hop, int size,
if (!ring)
goto err;

- mutex_init(&ring->lock);
+ spin_lock_init(&ring->lock);
INIT_LIST_HEAD(&ring->queue);
INIT_LIST_HEAD(&ring->in_flight);
INIT_WORK(&ring->work, ring_work);
@@ -371,8 +376,6 @@ static struct tb_ring *tb_ring_alloc(struct tb_nhi *nhi, u32 hop, int size,
return ring;

err:
- if (ring)
- mutex_destroy(&ring->lock);
kfree(ring);
mutex_unlock(&nhi->lock);
return NULL;
@@ -419,7 +422,7 @@ void tb_ring_start(struct tb_ring *ring)
u32 flags;

mutex_lock(&ring->nhi->lock);
- mutex_lock(&ring->lock);
+ spin_lock_irq(&ring->lock);
if (ring->nhi->going_away)
goto err;
if (ring->running) {
@@ -466,7 +469,7 @@ void tb_ring_start(struct tb_ring *ring)
ring_interrupt_active(ring, true);
ring->running = true;
err:
- mutex_unlock(&ring->lock);
+ spin_unlock_irq(&ring->lock);
mutex_unlock(&ring->nhi->lock);
}
EXPORT_SYMBOL_GPL(tb_ring_start);
@@ -487,7 +490,7 @@ EXPORT_SYMBOL_GPL(tb_ring_start);
void tb_ring_stop(struct tb_ring *ring)
{
mutex_lock(&ring->nhi->lock);
- mutex_lock(&ring->lock);
+ spin_lock_irq(&ring->lock);
dev_info(&ring->nhi->pdev->dev, "stopping %s %d\n",
RING_TYPE(ring), ring->hop);
if (ring->nhi->going_away)
@@ -508,7 +511,7 @@ void tb_ring_stop(struct tb_ring *ring)
ring->running = false;

err:
- mutex_unlock(&ring->lock);
+ spin_unlock_irq(&ring->lock);
mutex_unlock(&ring->nhi->lock);

/*
@@ -568,7 +571,6 @@ void tb_ring_free(struct tb_ring *ring)
* to finish before freeing the ring.
*/
flush_work(&ring->work);
- mutex_destroy(&ring->lock);
kfree(ring);
}
EXPORT_SYMBOL_GPL(tb_ring_free);
diff --git a/include/linux/thunderbolt.h b/include/linux/thunderbolt.h
index fac4ff62c0de..51af0a5fa52f 100644
--- a/include/linux/thunderbolt.h
+++ b/include/linux/thunderbolt.h
@@ -448,7 +448,7 @@ struct tb_nhi {
* @eof_mask: Bit mask used to detect end of frame PDF
*/
struct tb_ring {
- struct mutex lock;
+ spinlock_t lock;
struct tb_nhi *nhi;
int size;
int hop;
--
2.13.5
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