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drm/i915/gem: Delay tracking the GEM context until it is registered 

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 chase down some dangling
incomplete pointers.

Reported-by: CQ Tang <cq.tang@intel.com>
Fixes: 3aa9945a52 ("drm/i915: Separate GEM context construction and registration to userspace")
References: f6e8aa3871 ("drm/i915: Report the number of closed vma held by each context in debugfs")
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+
Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200730092856.23615-1-chris@chris-wilson.co.uk
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
(cherry picked from commit eb4dedae92)
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
This commit is contained in:
Chris Wilson 2020-07-30 10:28:56 +01:00 committed by Jani Nikula
parent 856deb866d
commit e7d95527f2
1 changed files with 11 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

16
drivers/gpu/drm/i915/gem/i915_gem_context.c
View File

@ -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;
}