Commit 6a8679c0 authored by Chris Wilson's avatar Chris Wilson
Browse files

drm/i915: Mark the GEM context link as RCU protected 



The only protection for intel_context.gem_cotext is granted by RCU, so
annotate it as a rcu protected pointer and carefully dereference it in
the few occasions we need to use it.

Fixes: 9f3ccd40 ("drm/i915: Drop GEM context as a direct link from i915_request")
Signed-off-by: default avatarChris Wilson <chris@chris-wilson.co.uk>
Cc: Andi Shyti <andi.shyti@intel.com>
Acked-by: default avatarAndi Shyti <andi.shyti@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191222233558.2201901-1-chris@chris-wilson.co.uk
parent 76f9764c

drivers/gpu/drm/i915/gem/i915_gem_context.c

+3 −2
Original line number Diff line number Diff line
@@ -212,8 +212,8 @@ context_get_vm_rcu(struct i915_gem_context *ctx) 
static void intel_context_set_gem(struct intel_context *ce,

				  struct i915_gem_context *ctx)

{

	GEM_BUG_ON(ce->gem_context);

	ce->gem_context = ctx;

	GEM_BUG_ON(rcu_access_pointer(ce->gem_context));

	RCU_INIT_POINTER(ce->gem_context, ctx);



	if (!test_bit(CONTEXT_ALLOC_BIT, &ce->flags))

		ce->ring = __intel_context_ring_size(SZ_16K);
@@ -244,6 +244,7 @@ static void __free_engines(struct i915_gem_engines *e, unsigned int count) 
		if (!e->engines[count])

			continue;



		RCU_INIT_POINTER(e->engines[count]->gem_context, NULL);

		intel_context_put(e->engines[count]);

	}

	kfree(e);

drivers/gpu/drm/i915/gt/intel_context_types.h

+1 −1
Original line number Diff line number Diff line
@@ -44,7 +44,7 @@ struct intel_context { 
#define intel_context_inflight_count(ce) ptr_unmask_bits((ce)->inflight, 2)



	struct i915_address_space *vm;

	struct i915_gem_context *gem_context;

	struct i915_gem_context __rcu *gem_context;



	struct list_head signal_link;

	struct list_head signals;

drivers/gpu/drm/i915/gt/intel_reset.c

+20 −6
Original line number Diff line number Diff line
@@ -85,20 +85,27 @@ static bool mark_guilty(struct i915_request *rq) 
	bool banned;

	int i;



	ctx = rq->context->gem_context;

	rcu_read_lock();

	ctx = rcu_dereference(rq->context->gem_context);

	if (ctx && !kref_get_unless_zero(&ctx->ref))

		ctx = NULL;

	rcu_read_unlock();

	if (!ctx)

		return false;



	if (i915_gem_context_is_closed(ctx)) {

		intel_context_set_banned(rq->context);

		return true;

		banned = true;

		goto out;

	}



	atomic_inc(&ctx->guilty_count);



	/* Cool contexts are too cool to be banned! (Used for reset testing.) */

	if (!i915_gem_context_is_bannable(ctx))

		return false;

	if (!i915_gem_context_is_bannable(ctx)) {

		banned = false;

		goto out;

	}



	dev_notice(ctx->i915->drm.dev,

		   "%s context reset due to GPU hang\n",
@@ -122,13 +129,20 @@ static bool mark_guilty(struct i915_request *rq) 


	client_mark_guilty(ctx, banned);



out:

	i915_gem_context_put(ctx);

	return banned;

}



static void mark_innocent(struct i915_request *rq)

{

	if (rq->context->gem_context)

		atomic_inc(&rq->context->gem_context->active_count);

	struct i915_gem_context *ctx;



	rcu_read_lock();

	ctx = rcu_dereference(rq->context->gem_context);

	if (ctx)

		atomic_inc(&ctx->active_count);

	rcu_read_unlock();

}



void __i915_request_reset(struct i915_request *rq, bool guilty)

drivers/gpu/drm/i915/gt/intel_ring_submission.c

+1 −1
Original line number Diff line number Diff line
@@ -1550,7 +1550,7 @@ static int remap_l3_slice(struct i915_request *rq, int slice) 


static int remap_l3(struct i915_request *rq)

{

	struct i915_gem_context *ctx = rq->context->gem_context;

	struct i915_gem_context *ctx = i915_request_gem_context(rq);

	int i, err;



	if (!ctx || !ctx->remap_slice)

drivers/gpu/drm/i915/i915_gpu_error.c

+26 −14
Original line number Diff line number Diff line
@@ -1221,7 +1221,7 @@ static void error_record_engine_registers(struct i915_gpu_state *error, 
static void record_request(const struct i915_request *request,

			   struct drm_i915_error_request *erq)

{

	const struct i915_gem_context *ctx = request->context->gem_context;

	const struct i915_gem_context *ctx;



	erq->flags = request->fence.flags;

	erq->context = request->fence.context;
@@ -1231,7 +1231,13 @@ static void record_request(const struct i915_request *request, 
	erq->start = i915_ggtt_offset(request->ring->vma);

	erq->head = request->head;

	erq->tail = request->tail;

	erq->pid = ctx && ctx->pid ? pid_nr(ctx->pid) : 0;



	erq->pid = 0;

	rcu_read_lock();

	ctx = rcu_dereference(request->context->gem_context);

	if (ctx)

		erq->pid = pid_nr(ctx->pid);

	rcu_read_unlock();

}



static void engine_record_requests(struct intel_engine_cs *engine,
@@ -1298,14 +1304,18 @@ static void error_record_engine_execlists(const struct intel_engine_cs *engine, 
static bool record_context(struct drm_i915_error_context *e,

			   const struct i915_request *rq)

{

	const struct i915_gem_context *ctx = rq->context->gem_context;

	struct i915_gem_context *ctx;

	struct task_struct *task;

	bool capture;



	rcu_read_lock();

	ctx = rcu_dereference(rq->context->gem_context);

	if (ctx && !kref_get_unless_zero(&ctx->ref))

		ctx = NULL;

	rcu_read_unlock();

	if (!ctx)

		return false;



	if (ctx->pid) {

		struct task_struct *task;



	rcu_read_lock();

	task = pid_task(ctx->pid, PIDTYPE_PID);

	if (task) {
@@ -1313,13 +1323,15 @@ static bool record_context(struct drm_i915_error_context *e, 
		e->pid = task->pid;

	}

	rcu_read_unlock();

	}



	e->sched_attr = ctx->sched;

	e->guilty = atomic_read(&ctx->guilty_count);

	e->active = atomic_read(&ctx->active_count);



	return i915_gem_context_no_error_capture(ctx);

	capture = i915_gem_context_no_error_capture(ctx);



	i915_gem_context_put(ctx);

	return capture;

}



struct capture_vma {

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