[PATCH] drm/i915: release context ID when context creation fails

[Sang-Hoon Choi <csh0052@gmail.com>]

On graphics version 13 and later, xa_alloc() reserves a context ID before
i915_gem_create_context() is called. If context creation fails, the
reserved entry is left in context_xa, making the ID unavailable to later
context allocations on the same DRM file.

Release the unused XArray reservation on the failure path.

Fixes: ca06f9363836 ("drm/i915: Finalize contexts in GEM_CONTEXT_CREATE on version 13+")
Reported-by: Changyul Lee <lcy8047@gmail.com>
Assisted-by: LLM
Signed-off-by: Sang-Hoon Choi <csh0052@gmail.com>
---
Compile-tested the affected object with x86_64 allmodconfig
and W=1 (GCC 13.3.0). Base: mainline 3b7cab693ba2bab63774bf5b988e8a61b2ef0f32.
No hardware testing or runtime failure reproduction was performed.

 drivers/gpu/drm/i915/gem/i915_gem_context.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_context.c b/drivers/gpu/drm/i915/gem/i915_gem_context.c
index c58ffa5a8fa6..4eb715c2da1c 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_context.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_context.c
@@ -2421,6 +2421,7 @@ int i915_gem_context_create_ioctl(struct drm_device *dev, void *data,
 		ctx = i915_gem_create_context(i915, ext_data.pc);
 		if (IS_ERR(ctx)) {
 			ret = PTR_ERR(ctx);
+			xa_release(&ext_data.fpriv->context_xa, id);
 			goto err_pc;
 		}