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

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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: 9f3ccd40ac ("drm/i915: Drop GEM context as a direct link from i915_request")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Andi Shyti <andi.shyti@intel.com>
Acked-by: Andi Shyti <andi.shyti@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191222233558.2201901-1-chris@chris-wilson.co.uk
This commit is contained in:
Chris Wilson
2019-12-22 23:35:58 +00:00
parent 76f9764cc3
commit 6a8679c048
7 changed files with 62 additions and 27 deletions
Download Patch File Download Diff File Expand all files Collapse all files

5
drivers/gpu/drm/i915/gem/i915_gem_context.c
View File

@@ -212,8 +212,8 @@ context_get_vm_rcu(struct i915_gem_context *ctx)
static void intel_context_set_gem(struct intel_context *ce, static void intel_context_set_gem(struct intel_context *ce,
struct i915_gem_context *ctx) struct i915_gem_context *ctx)
{ {
GEM_BUG_ON(ce->gem_context); GEM_BUG_ON(rcu_access_pointer(ce->gem_context));
ce->gem_context = ctx; RCU_INIT_POINTER(ce->gem_context, ctx);
if (!test_bit(CONTEXT_ALLOC_BIT, &ce->flags)) if (!test_bit(CONTEXT_ALLOC_BIT, &ce->flags))
ce->ring = __intel_context_ring_size(SZ_16K); 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]) if (!e->engines[count])
continue; continue;
RCU_INIT_POINTER(e->engines[count]->gem_context, NULL);
intel_context_put(e->engines[count]); intel_context_put(e->engines[count]);
} }
kfree(e); kfree(e);

2
drivers/gpu/drm/i915/gt/intel_context_types.h
View File

@@ -44,7 +44,7 @@ struct intel_context {
#define intel_context_inflight_count(ce) ptr_unmask_bits((ce)->inflight, 2) #define intel_context_inflight_count(ce) ptr_unmask_bits((ce)->inflight, 2)
struct i915_address_space *vm; 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 signal_link;
struct list_head signals; struct list_head signals;

26
drivers/gpu/drm/i915/gt/intel_reset.c
View File

@@ -85,20 +85,27 @@ static bool mark_guilty(struct i915_request *rq)
bool banned; bool banned;
int i; 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) if (!ctx)
return false; return false;
if (i915_gem_context_is_closed(ctx)) { if (i915_gem_context_is_closed(ctx)) {
intel_context_set_banned(rq->context); intel_context_set_banned(rq->context);
return true; banned = true;
goto out;
} }
atomic_inc(&ctx->guilty_count); atomic_inc(&ctx->guilty_count);
/* Cool contexts are too cool to be banned! (Used for reset testing.) */ /* Cool contexts are too cool to be banned! (Used for reset testing.) */
if (!i915_gem_context_is_bannable(ctx)) if (!i915_gem_context_is_bannable(ctx)) {
return false; banned = false;
goto out;
}
dev_notice(ctx->i915->drm.dev, dev_notice(ctx->i915->drm.dev,
"%s context reset due to GPU hang\n", "%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); client_mark_guilty(ctx, banned);
out:
i915_gem_context_put(ctx);
return banned; return banned;
} }
static void mark_innocent(struct i915_request *rq) static void mark_innocent(struct i915_request *rq)
{ {
if (rq->context->gem_context) struct i915_gem_context *ctx;
atomic_inc(&rq->context->gem_context->active_count);
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) void __i915_request_reset(struct i915_request *rq, bool guilty)

2
drivers/gpu/drm/i915/gt/intel_ring_submission.c
View File

@@ -1550,7 +1550,7 @@ static int remap_l3_slice(struct i915_request *rq, int slice)
static int remap_l3(struct i915_request *rq) 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; int i, err;
if (!ctx || !ctx->remap_slice) if (!ctx || !ctx->remap_slice)

40
drivers/gpu/drm/i915/i915_gpu_error.c
View File

@@ -1221,7 +1221,7 @@ static void error_record_engine_registers(struct i915_gpu_state *error,
static void record_request(const struct i915_request *request, static void record_request(const struct i915_request *request,
struct drm_i915_error_request *erq) 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->flags = request->fence.flags;
erq->context = request->fence.context; 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->start = i915_ggtt_offset(request->ring->vma);
erq->head = request->head; erq->head = request->head;
erq->tail = request->tail; 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, static void engine_record_requests(struct intel_engine_cs *engine,
@@ -1298,28 +1304,34 @@ static void error_record_engine_execlists(const struct intel_engine_cs *engine,
static bool record_context(struct drm_i915_error_context *e, static bool record_context(struct drm_i915_error_context *e,
const struct i915_request *rq) 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) if (!ctx)
return false; return false;
if (ctx->pid) { rcu_read_lock();
struct task_struct *task; task = pid_task(ctx->pid, PIDTYPE_PID);
if (task) {
rcu_read_lock(); strcpy(e->comm, task->comm);
task = pid_task(ctx->pid, PIDTYPE_PID); e->pid = task->pid;
if (task) {
strcpy(e->comm, task->comm);
e->pid = task->pid;
}
rcu_read_unlock();
} }
rcu_read_unlock();
e->sched_attr = ctx->sched; e->sched_attr = ctx->sched;
e->guilty = atomic_read(&ctx->guilty_count); e->guilty = atomic_read(&ctx->guilty_count);
e->active = atomic_read(&ctx->active_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 { struct capture_vma {

6
drivers/gpu/drm/i915/i915_request.c
View File

@@ -76,7 +76,7 @@ static const char *i915_fence_get_timeline_name(struct dma_fence *fence)
if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags)) if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags))
return "signaled"; return "signaled";
ctx = to_request(fence)->context->gem_context; ctx = i915_request_gem_context(to_request(fence));
if (!ctx) if (!ctx)
return "[" DRIVER_NAME "]"; return "[" DRIVER_NAME "]";
@@ -1312,8 +1312,8 @@ void i915_request_add(struct i915_request *rq)
prev = __i915_request_commit(rq); prev = __i915_request_commit(rq);
if (rq->context->gem_context) if (rcu_access_pointer(rq->context->gem_context))
attr = rq->context->gem_context->sched; attr = i915_request_gem_context(rq)->sched;
/* /*
* Boost actual workloads past semaphores! * Boost actual workloads past semaphores!

8
drivers/gpu/drm/i915/i915_request.h
View File

@@ -28,6 +28,7 @@
#include <linux/dma-fence.h> #include <linux/dma-fence.h>
#include <linux/lockdep.h> #include <linux/lockdep.h>
#include "gem/i915_gem_context_types.h"
#include "gt/intel_context_types.h" #include "gt/intel_context_types.h"
#include "gt/intel_engine_types.h" #include "gt/intel_engine_types.h"
#include "gt/intel_timeline_types.h" #include "gt/intel_timeline_types.h"
@@ -463,6 +464,13 @@ i915_request_timeline(struct i915_request *rq)
lockdep_is_held(&rcu_access_pointer(rq->timeline)->mutex)); lockdep_is_held(&rcu_access_pointer(rq->timeline)->mutex));
} }
static inline struct i915_gem_context *
i915_request_gem_context(struct i915_request *rq)
{
/* Valid only while the request is being constructed (or retired). */
return rcu_dereference_protected(rq->context->gem_context, true);
}
static inline struct intel_timeline * static inline struct intel_timeline *
i915_request_active_timeline(struct i915_request *rq) i915_request_active_timeline(struct i915_request *rq)
{ {