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* [Intel-gfx] [PATCH] drm/i915/gem: Delay tracking the GEM context until it is registered
@ 2020-07-23 18:33 Chris Wilson
  2020-07-23 18:35 ` Chris Wilson
                   ` (7 more replies)
  0 siblings, 8 replies; 12+ messages in thread
From: Chris Wilson @ 2020-07-23 18:33 UTC (permalink / raw)
  To: intel-gfx; +Cc: stable, Chris Wilson

Avoid exposing a partially constructed context by deferring the
list_add() from the initial construction to the end of registration.
Otherwise, if we peek into the list of contexts from inside debugfs, we
may see the partially constructed context and change down some dangling
incomplete pointers.

Reported-by: CQ Tang <cq.tang@intel.com>
Fixes: b91715417244 ("drm/i915: Extend CONTEXT_CREATE to set parameters upon construction")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: CQ Tang <cq.tang@intel.com>
Cc: <stable@vger.kernel.org> # v5.2+
---
 drivers/gpu/drm/i915/gem/i915_gem_context.c | 16 +++++++++++-----
 1 file changed, 11 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_context.c b/drivers/gpu/drm/i915/gem/i915_gem_context.c
index d0bdb6d447ed..efc4ba34c06e 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_context.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_context.c
@@ -713,6 +713,7 @@ __create_context(struct drm_i915_private *i915)
 	ctx->i915 = i915;
 	ctx->sched.priority = I915_USER_PRIORITY(I915_PRIORITY_NORMAL);
 	mutex_init(&ctx->mutex);
+	INIT_LIST_HEAD(&ctx->link);
 
 	spin_lock_init(&ctx->stale.lock);
 	INIT_LIST_HEAD(&ctx->stale.engines);
@@ -740,10 +741,6 @@ __create_context(struct drm_i915_private *i915)
 	for (i = 0; i < ARRAY_SIZE(ctx->hang_timestamp); i++)
 		ctx->hang_timestamp[i] = jiffies - CONTEXT_FAST_HANG_JIFFIES;
 
-	spin_lock(&i915->gem.contexts.lock);
-	list_add_tail(&ctx->link, &i915->gem.contexts.list);
-	spin_unlock(&i915->gem.contexts.lock);
-
 	return ctx;
 
 err_free:
@@ -931,6 +928,7 @@ static int gem_context_register(struct i915_gem_context *ctx,
 				struct drm_i915_file_private *fpriv,
 				u32 *id)
 {
+	struct drm_i915_private *i915 = ctx->i915;
 	struct i915_address_space *vm;
 	int ret;
 
@@ -949,8 +947,16 @@ static int gem_context_register(struct i915_gem_context *ctx,
 	/* And finally expose ourselves to userspace via the idr */
 	ret = xa_alloc(&fpriv->context_xa, id, ctx, xa_limit_32b, GFP_KERNEL);
 	if (ret)
-		put_pid(fetch_and_zero(&ctx->pid));
+		goto err_pid;
+
+	spin_lock(&i915->gem.contexts.lock);
+	list_add_tail(&ctx->link, &i915->gem.contexts.list);
+	spin_unlock(&i915->gem.contexts.lock);
+
+	return 0;
 
+err_pid:
+	put_pid(fetch_and_zero(&ctx->pid));
 	return ret;
 }
 
-- 
2.20.1

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^ permalink raw reply related	[flat|nested] 12+ messages in thread
end of thread, other threads:[~2020-07-24 12:56 UTC | newest]

Thread overview: 12+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2020-07-23 18:33 [Intel-gfx] [PATCH] drm/i915/gem: Delay tracking the GEM context until it is registered Chris Wilson
2020-07-23 18:35 ` Chris Wilson
2020-07-24 11:55   ` Mika Kuoppala
2020-07-24 12:06     ` Chris Wilson
2020-07-24 12:31       ` Mika Kuoppala
2020-07-23 18:46 ` [Intel-gfx] ✗ Fi.CI.SPARSE: warning for " Patchwork
2020-07-23 19:07 ` [Intel-gfx] ✓ Fi.CI.BAT: success " Patchwork
2020-07-23 22:49 ` [Intel-gfx] ✓ Fi.CI.IGT: " Patchwork
2020-07-24 12:07 ` [Intel-gfx] [PATCH] " Chris Wilson
2020-07-24 12:34 ` [Intel-gfx] ✗ Fi.CI.CHECKPATCH: warning for drm/i915/gem: Delay tracking the GEM context until it is registered (rev2) Patchwork
2020-07-24 12:34 ` [Intel-gfx] ✗ Fi.CI.SPARSE: " Patchwork
2020-07-24 12:56 ` [Intel-gfx] ✗ Fi.CI.BAT: failure " Patchwork

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