On 01/12/15 00:15, Dai, Yu wrote:
From: Alex Dai <yu.dai@xxxxxxxxx>
When GuC Work Queue is full, driver will wait GuC for avaliable
space by delaying 1ms. The wait needs to be out of spinlockirq /
unlock. Otherwise, lockup happens because jiffies won't be updated
due to irq is disabled. The unnecessary locks has been cleared.
dev->struct_mutex is used instead where needed.
Issue is found in igt/gem_close_race.
v3: Remove unnecessary whitespace churn
v2: Clean up wq_lock too
v1: Clean up host2guc lock as well
Signed-off-by: Alex Dai <yu.dai@xxxxxxxxx>
A few typos in the commit message, as pointed out by Nick in the
previous review cycle, but the code looks OK so
Reviewed-by: Dave Gordon <david.s.gordon@xxxxxxxxx>
and here's a suggestion for the commit message, with a
bit more background and more 'why' rather than 'what':
: For now, remove the spinlocks that protected the GuC's
: statistics block and work queue; they are only accessed
: by code that already holds the global struct_mutex, and
: so are redundant (until the big struct_mutex rewrite!).
:
: The specific problem that the spinlocks caused was that
: if the work queue was full, the driver would try to
: spinwait for one jiffy, but with interrupts disabled the
: jiffy count would not advance, leading to a system hang.
: The issue was found using test case igt/gem_close_race.
:
: The new version will usleep() instead, still holding
: the struct_mutex but without any spinlocks.
---
drivers/gpu/drm/i915/i915_debugfs.c | 12 ++++++------
drivers/gpu/drm/i915/i915_guc_submission.c | 31 ++++++------------------------
drivers/gpu/drm/i915/intel_guc.h | 4 ----
3 files changed, 12 insertions(+), 35 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
index a728ff1..d6b7817 100644
--- a/drivers/gpu/drm/i915/i915_debugfs.c
+++ b/drivers/gpu/drm/i915/i915_debugfs.c
@@ -2473,15 +2473,15 @@ static int i915_guc_info(struct seq_file *m, void *data)
if (!HAS_GUC_SCHED(dev_priv->dev))
return 0;
+ if (mutex_lock_interruptible(&dev->struct_mutex))
+ return 0;
+
/* Take a local copy of the GuC data, so we can dump it at leisure */
- spin_lock(&dev_priv->guc.host2guc_lock);
guc = dev_priv->guc;
- if (guc.execbuf_client) {
- spin_lock(&guc.execbuf_client->wq_lock);
+ if (guc.execbuf_client)
client = *guc.execbuf_client;
- spin_unlock(&guc.execbuf_client->wq_lock);
- }
- spin_unlock(&dev_priv->guc.host2guc_lock);
+
+ mutex_unlock(&dev->struct_mutex);
seq_printf(m, "GuC total action count: %llu\n", guc.action_count);
seq_printf(m, "GuC action failure count: %u\n", guc.action_fail);
diff --git a/drivers/gpu/drm/i915/i915_guc_submission.c b/drivers/gpu/drm/i915/i915_guc_submission.c
index ed9f100..a7f9785 100644
--- a/drivers/gpu/drm/i915/i915_guc_submission.c
+++ b/drivers/gpu/drm/i915/i915_guc_submission.c
@@ -86,7 +86,6 @@ static int host2guc_action(struct intel_guc *guc, u32 *data, u32 len)
return -EINVAL;
intel_uncore_forcewake_get(dev_priv, FORCEWAKE_ALL);
- spin_lock(&dev_priv->guc.host2guc_lock);
dev_priv->guc.action_count += 1;
dev_priv->guc.action_cmd = data[0];
@@ -119,7 +118,6 @@ static int host2guc_action(struct intel_guc *guc, u32 *data, u32 len)
}
dev_priv->guc.action_status = status;
- spin_unlock(&dev_priv->guc.host2guc_lock);
intel_uncore_forcewake_put(dev_priv, FORCEWAKE_ALL);
return ret;
@@ -292,16 +290,12 @@ static uint32_t select_doorbell_cacheline(struct intel_guc *guc)
const uint32_t cacheline_size = cache_line_size();
uint32_t offset;
- spin_lock(&guc->host2guc_lock);
-
/* Doorbell uses a single cache line within a page */
offset = offset_in_page(guc->db_cacheline);
/* Moving to next cache line to reduce contention */
guc->db_cacheline += cacheline_size;
- spin_unlock(&guc->host2guc_lock);
-
DRM_DEBUG_DRIVER("selected doorbell cacheline 0x%x, next 0x%x, linesize %u\n",
offset, guc->db_cacheline, cacheline_size);
@@ -322,13 +316,11 @@ static uint16_t assign_doorbell(struct intel_guc *guc, uint32_t priority)
const uint16_t end = start + half;
uint16_t id;
- spin_lock(&guc->host2guc_lock);
id = find_next_zero_bit(guc->doorbell_bitmap, end, start);
if (id == end)
id = GUC_INVALID_DOORBELL_ID;
else
bitmap_set(guc->doorbell_bitmap, id, 1);
- spin_unlock(&guc->host2guc_lock);
DRM_DEBUG_DRIVER("assigned %s priority doorbell id 0x%x\n",
hi_pri ? "high" : "normal", id);
@@ -338,9 +330,7 @@ static uint16_t assign_doorbell(struct intel_guc *guc, uint32_t priority)
static void release_doorbell(struct intel_guc *guc, uint16_t id)
{
- spin_lock(&guc->host2guc_lock);
bitmap_clear(guc->doorbell_bitmap, id, 1);
- spin_unlock(&guc->host2guc_lock);
}
/*
@@ -487,16 +477,13 @@ static int guc_get_workqueue_space(struct i915_guc_client *gc, u32 *offset)
struct guc_process_desc *desc;
void *base;
u32 size = sizeof(struct guc_wq_item);
- int ret = 0, timeout_counter = 200;
+ int ret = -ETIMEDOUT, timeout_counter = 200;
base = kmap_atomic(i915_gem_object_get_page(gc->client_obj, 0));
desc = base + gc->proc_desc_offset;
while (timeout_counter-- > 0) {
- ret = wait_for_atomic(CIRC_SPACE(gc->wq_tail, desc->head,
- gc->wq_size) >= size, 1);
-
- if (!ret) {
+ if (CIRC_SPACE(gc->wq_tail, desc->head, gc->wq_size) >= size) {
*offset = gc->wq_tail;
/* advance the tail for next workqueue item */
@@ -505,7 +492,11 @@ static int guc_get_workqueue_space(struct i915_guc_client *gc, u32 *offset)
/* this will break the loop */
timeout_counter = 0;
+ ret = 0;
}
+
+ if (timeout_counter)
+ usleep_range(1000, 2000);
};
kunmap_atomic(base);
@@ -597,15 +588,12 @@ int i915_guc_submit(struct i915_guc_client *client,
{
struct intel_guc *guc = client->guc;
enum intel_ring_id ring_id = rq->ring->id;
- unsigned long flags;
int q_ret, b_ret;
/* Need this because of the deferred pin ctx and ring */
/* Shall we move this right after ring is pinned? */
lr_context_update(rq);
- spin_lock_irqsave(&client->wq_lock, flags);
-
q_ret = guc_add_workqueue_item(client, rq);
if (q_ret == 0)
b_ret = guc_ring_doorbell(client);
@@ -620,12 +608,8 @@ int i915_guc_submit(struct i915_guc_client *client,
} else {
client->retcode = 0;
}
- spin_unlock_irqrestore(&client->wq_lock, flags);
-
- spin_lock(&guc->host2guc_lock);
guc->submissions[ring_id] += 1;
guc->last_seqno[ring_id] = rq->seqno;
- spin_unlock(&guc->host2guc_lock);
return q_ret;
}
@@ -768,7 +752,6 @@ static struct i915_guc_client *guc_client_alloc(struct drm_device *dev,
client->client_obj = obj;
client->wq_offset = GUC_DB_SIZE;
client->wq_size = GUC_WQ_SIZE;
- spin_lock_init(&client->wq_lock);
client->doorbell_offset = select_doorbell_cacheline(guc);
@@ -871,8 +854,6 @@ int i915_guc_submission_init(struct drm_device *dev)
if (!guc->ctx_pool_obj)
return -ENOMEM;
- spin_lock_init(&dev_priv->guc.host2guc_lock);
-
ida_init(&guc->ctx_ids);
guc_create_log(guc);
diff --git a/drivers/gpu/drm/i915/intel_guc.h b/drivers/gpu/drm/i915/intel_guc.h
index 5ba5866..8229522 100644
--- a/drivers/gpu/drm/i915/intel_guc.h
+++ b/drivers/gpu/drm/i915/intel_guc.h
@@ -42,8 +42,6 @@ struct i915_guc_client {
uint32_t wq_offset;
uint32_t wq_size;
-
- spinlock_t wq_lock; /* Protects all data below */
uint32_t wq_tail;
/* GuC submission statistics & status */
@@ -95,8 +93,6 @@ struct intel_guc {
struct i915_guc_client *execbuf_client;
- spinlock_t host2guc_lock; /* Protects all data below */
-
DECLARE_BITMAP(doorbell_bitmap, GUC_MAX_DOORBELLS);
uint32_t db_cacheline; /* Cyclic counter mod pagesize */
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