Commit 07779a76 authored by Chris Wilson's avatar Chris Wilson

drm/i915: Mark up the calling context for intel_wakeref_put()

Previously, we assumed we could use mutex_trylock() within an atomic
context, falling back to a worker if contended. However, such trickery
is illegal inside interrupt context, and so we need to always use a
worker under such circumstances. As we normally are in process context,
we can typically use a plain mutex, and only defer to a work when we
know we are being called from an interrupt path.

Fixes: 51fbd8de ("drm/i915/pmu: Atomically acquire the gt_pm wakeref")
References: a0855d24 ("locking/mutex: Complain upon mutex API misuse in IRQ contexts")
References: https://bugs.freedesktop.org/show_bug.cgi?id=111626Signed-off-by: default avatarChris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: default avatarTvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191120125433.3767149-1-chris@chris-wilson.co.uk
parent 8a126392
......@@ -177,7 +177,8 @@ static int __engine_park(struct intel_wakeref *wf)
engine->execlists.no_priolist = false;
intel_gt_pm_put(engine->gt);
/* While gt calls i915_vma_parked(), we have to break the lock cycle */
intel_gt_pm_put_async(engine->gt);
return 0;
}
......
......@@ -31,6 +31,16 @@ static inline void intel_engine_pm_put(struct intel_engine_cs *engine)
intel_wakeref_put(&engine->wakeref);
}
static inline void intel_engine_pm_put_async(struct intel_engine_cs *engine)
{
intel_wakeref_put_async(&engine->wakeref);
}
static inline void intel_engine_pm_flush(struct intel_engine_cs *engine)
{
intel_wakeref_unlock_wait(&engine->wakeref);
}
void intel_engine_init__pm(struct intel_engine_cs *engine);
#endif /* INTEL_ENGINE_PM_H */
......@@ -105,7 +105,6 @@ static int __gt_park(struct intel_wakeref *wf)
static const struct intel_wakeref_ops wf_ops = {
.get = __gt_unpark,
.put = __gt_park,
.flags = INTEL_WAKEREF_PUT_ASYNC,
};
void intel_gt_pm_init_early(struct intel_gt *gt)
......
......@@ -32,6 +32,11 @@ static inline void intel_gt_pm_put(struct intel_gt *gt)
intel_wakeref_put(&gt->wakeref);
}
static inline void intel_gt_pm_put_async(struct intel_gt *gt)
{
intel_wakeref_put_async(&gt->wakeref);
}
static inline int intel_gt_pm_wait_for_idle(struct intel_gt *gt)
{
return intel_wakeref_wait_for_idle(&gt->wakeref);
......
......@@ -1172,7 +1172,7 @@ __execlists_schedule_out(struct i915_request *rq,
intel_engine_context_out(engine);
execlists_context_status_change(rq, INTEL_CONTEXT_SCHEDULE_OUT);
intel_gt_pm_put(engine->gt);
intel_gt_pm_put_async(engine->gt);
/*
* If this is part of a virtual engine, its next request may
......
......@@ -1125,7 +1125,7 @@ int intel_engine_reset(struct intel_engine_cs *engine, const char *msg)
out:
intel_engine_cancel_stop_cs(engine);
reset_finish_engine(engine);
intel_engine_pm_put(engine);
intel_engine_pm_put_async(engine);
return ret;
}
......
......@@ -51,11 +51,12 @@ static int live_engine_pm(void *arg)
pr_err("intel_engine_pm_get_if_awake(%s) failed under %s\n",
engine->name, p->name);
else
intel_engine_pm_put(engine);
intel_engine_pm_put(engine);
intel_engine_pm_put_async(engine);
intel_engine_pm_put_async(engine);
p->critical_section_end();
/* engine wakeref is sync (instant) */
intel_engine_pm_flush(engine);
if (intel_engine_pm_is_awake(engine)) {
pr_err("%s is still awake after flushing pm\n",
engine->name);
......
......@@ -672,12 +672,13 @@ void i915_active_acquire_barrier(struct i915_active *ref)
* populated by i915_request_add_active_barriers() to point to the
* request that will eventually release them.
*/
spin_lock_irqsave_nested(&ref->tree_lock, flags, SINGLE_DEPTH_NESTING);
llist_for_each_safe(pos, next, take_preallocated_barriers(ref)) {
struct active_node *node = barrier_from_ll(pos);
struct intel_engine_cs *engine = barrier_to_engine(node);
struct rb_node **p, *parent;
spin_lock_irqsave_nested(&ref->tree_lock, flags,
SINGLE_DEPTH_NESTING);
parent = NULL;
p = &ref->tree.rb_node;
while (*p) {
......@@ -693,12 +694,12 @@ void i915_active_acquire_barrier(struct i915_active *ref)
}
rb_link_node(&node->node, parent, p);
rb_insert_color(&node->node, &ref->tree);
spin_unlock_irqrestore(&ref->tree_lock, flags);
GEM_BUG_ON(!intel_engine_pm_is_awake(engine));
llist_add(barrier_to_ll(node), &engine->barrier_tasks);
intel_engine_pm_put(engine);
}
spin_unlock_irqrestore(&ref->tree_lock, flags);
}
void i915_request_add_active_barriers(struct i915_request *rq)
......
......@@ -190,7 +190,7 @@ static u64 get_rc6(struct intel_gt *gt)
val = 0;
if (intel_gt_pm_get_if_awake(gt)) {
val = __get_rc6(gt);
intel_gt_pm_put(gt);
intel_gt_pm_put_async(gt);
}
spin_lock_irqsave(&pmu->lock, flags);
......@@ -360,7 +360,7 @@ engines_sample(struct intel_gt *gt, unsigned int period_ns)
skip:
if (unlikely(mmio_lock))
spin_unlock_irqrestore(mmio_lock, flags);
intel_engine_pm_put(engine);
intel_engine_pm_put_async(engine);
}
}
......@@ -398,7 +398,7 @@ frequency_sample(struct intel_gt *gt, unsigned int period_ns)
if (stat)
val = intel_get_cagf(rps, stat);
intel_gt_pm_put(gt);
intel_gt_pm_put_async(gt);
}
add_sample_mult(&pmu->sample[__I915_SAMPLE_FREQ_ACT],
......
......@@ -54,7 +54,8 @@ int __intel_wakeref_get_first(struct intel_wakeref *wf)
static void ____intel_wakeref_put_last(struct intel_wakeref *wf)
{
if (!atomic_dec_and_test(&wf->count))
INTEL_WAKEREF_BUG_ON(atomic_read(&wf->count) <= 0);
if (unlikely(!atomic_dec_and_test(&wf->count)))
goto unlock;
/* ops->put() must reschedule its own release on error/deferral */
......@@ -67,13 +68,12 @@ static void ____intel_wakeref_put_last(struct intel_wakeref *wf)
mutex_unlock(&wf->mutex);
}
void __intel_wakeref_put_last(struct intel_wakeref *wf)
void __intel_wakeref_put_last(struct intel_wakeref *wf, unsigned long flags)
{
INTEL_WAKEREF_BUG_ON(work_pending(&wf->work));
/* Assume we are not in process context and so cannot sleep. */
if (wf->ops->flags & INTEL_WAKEREF_PUT_ASYNC ||
!mutex_trylock(&wf->mutex)) {
if (flags & INTEL_WAKEREF_PUT_ASYNC || !mutex_trylock(&wf->mutex)) {
schedule_work(&wf->work);
return;
}
......
......@@ -9,6 +9,7 @@
#include <linux/atomic.h>
#include <linux/bits.h>
#include <linux/lockdep.h>
#include <linux/mutex.h>
#include <linux/refcount.h>
#include <linux/stackdepot.h>
......@@ -29,9 +30,6 @@ typedef depot_stack_handle_t intel_wakeref_t;
struct intel_wakeref_ops {
int (*get)(struct intel_wakeref *wf);
int (*put)(struct intel_wakeref *wf);
unsigned long flags;
#define INTEL_WAKEREF_PUT_ASYNC BIT(0)
};
struct intel_wakeref {
......@@ -57,7 +55,7 @@ void __intel_wakeref_init(struct intel_wakeref *wf,
} while (0)
int __intel_wakeref_get_first(struct intel_wakeref *wf);
void __intel_wakeref_put_last(struct intel_wakeref *wf);
void __intel_wakeref_put_last(struct intel_wakeref *wf, unsigned long flags);
/**
* intel_wakeref_get: Acquire the wakeref
......@@ -100,10 +98,9 @@ intel_wakeref_get_if_active(struct intel_wakeref *wf)
}
/**
* intel_wakeref_put: Release the wakeref
* @i915: the drm_i915_private device
* intel_wakeref_put_flags: Release the wakeref
* @wf: the wakeref
* @fn: callback for releasing the wakeref, called only on final release.
* @flags: control flags
*
* Release our hold on the wakeref. When there are no more users,
* the runtime pm wakeref will be released after the @fn callback is called
......@@ -116,11 +113,25 @@ intel_wakeref_get_if_active(struct intel_wakeref *wf)
* code otherwise.
*/
static inline void
intel_wakeref_put(struct intel_wakeref *wf)
__intel_wakeref_put(struct intel_wakeref *wf, unsigned long flags)
#define INTEL_WAKEREF_PUT_ASYNC BIT(0)
{
INTEL_WAKEREF_BUG_ON(atomic_read(&wf->count) <= 0);
if (unlikely(!atomic_add_unless(&wf->count, -1, 1)))
__intel_wakeref_put_last(wf);
__intel_wakeref_put_last(wf, flags);
}
static inline void
intel_wakeref_put(struct intel_wakeref *wf)
{
might_sleep();
__intel_wakeref_put(wf, 0);
}
static inline void
intel_wakeref_put_async(struct intel_wakeref *wf)
{
__intel_wakeref_put(wf, INTEL_WAKEREF_PUT_ASYNC);
}
/**
......@@ -185,6 +196,7 @@ intel_wakeref_is_active(const struct intel_wakeref *wf)
static inline void
__intel_wakeref_defer_park(struct intel_wakeref *wf)
{
lockdep_assert_held(&wf->mutex);
INTEL_WAKEREF_BUG_ON(atomic_read(&wf->count));
atomic_set_release(&wf->count, 1);
}
......
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