[PATCH v3 0/2] Add scope-based cleanup capability to eventfd_ctx

[PATCH v3 0/2] Add scope-based cleanup capability to eventfd_ctx

[Bence Csokas]

Add __free() support to eventfd and update drm_syncobj to use it as an
example consumer.

A minor discrepancy I encountered is whether to put a semicolon after
DEFINE_FREE(). It seems some in-tree code does, some doesn't. In the end,
I followed the example set in core-api/cleanup.rst, and omitted it.

Signed-off-by: Bence Csokas <bence.csokas@arm.com>
---
Changes in v3:
- IS_ERR_OR_NULL() moved into DEFINE_FREE() body
- Link to v2: https://patch.msgid.link/20260915-efd-autofree-v2-0-06d2c9d1547f@arm.com

Changes in v2:
- IS_ERR_OR_NULL() check, instead of NULLing out pointer on IS_ERR
- Link to v1: https://patch.msgid.link/20260909-efd-autofree-v1-0-c6c3c19cc702@arm.com

To: Alexander Viro <viro@zeniv.linux.org.uk>
To: Christian Brauner <brauner@kernel.org>
To: Jan Kara <jack@suse.cz>
To: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
To: Maxime Ripard <mripard@kernel.org>
To: Thomas Zimmermann <tzimmermann@suse.de>
To: David Airlie <airlied@gmail.com>
To: Simona Vetter <simona@ffwll.ch>
Cc: linux-fsdevel@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: dri-devel@lists.freedesktop.org

---
Bence Csokas (2):
      eventfd: Add scope-based cleanup capability
      drm/syncobj: Use scope-based cleanup for eventfd_ctx

 drivers/gpu/drm/drm_syncobj.c | 8 +++-----
 include/linux/eventfd.h       | 3 +++
 2 files changed, 6 insertions(+), 5 deletions(-)
---
base-commit: d135ab453a7400a34930bdda1ef4bdc8acfac80e
change-id: 20260826-efd-autofree-766608e8d8aa

Best regards,
--  
Bence Csokas <bence.csokas@arm.com>

[PATCH v3 1/2] eventfd: Add scope-based cleanup capability

[Bence Csokas]

Allow eventfd_ctx_put() to be used with the RAII-inspired __free() API.

Signed-off-by: Bence Csokas <bence.csokas@arm.com>
---
 include/linux/eventfd.h | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/include/linux/eventfd.h b/include/linux/eventfd.h
index e32bee4345fb..48c40f8c4dfd 100644
--- a/include/linux/eventfd.h
+++ b/include/linux/eventfd.h
@@ -10,6 +10,7 @@
 #define _LINUX_EVENTFD_H
 
 #include <linux/wait.h>
+#include <linux/cleanup.h>
 #include <linux/err.h>
 #include <linux/percpu-defs.h>
 #include <linux/percpu.h>
@@ -89,5 +90,7 @@ static inline void eventfd_signal(struct eventfd_ctx *ctx)
 	eventfd_signal_mask(ctx, 0);
 }
 
+DEFINE_FREE(eventfd, struct eventfd_ctx *, if (!IS_ERR_OR_NULL(_T)) eventfd_ctx_put(_T))
+
 #endif /* _LINUX_EVENTFD_H */
 

-- 
2.56.0

[PATCH v3 2/2] drm/syncobj: Use scope-based cleanup for eventfd_ctx

[Bence Csokas]

Now that eventfd supports __free(), use it in drm_syncobj_eventfd_ioctl().

Signed-off-by: Bence Csokas <bence.csokas@arm.com>
---
 drivers/gpu/drm/drm_syncobj.c | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/drm_syncobj.c b/drivers/gpu/drm/drm_syncobj.c
index f1d4da168545..40bedd30b2fc 100644
--- a/drivers/gpu/drm/drm_syncobj.c
+++ b/drivers/gpu/drm/drm_syncobj.c
@@ -1429,9 +1429,9 @@ int
 drm_syncobj_eventfd_ioctl(struct drm_device *dev, void *data,
 			  struct drm_file *file_private)
 {
+	struct eventfd_ctx *ev_fd_ctx __free(eventfd) = NULL;
 	struct drm_syncobj_eventfd *args = data;
 	struct drm_syncobj *syncobj;
-	struct eventfd_ctx *ev_fd_ctx;
 	struct syncobj_eventfd_entry *entry;
 	int ret;
 
@@ -1457,10 +1457,10 @@ drm_syncobj_eventfd_ioctl(struct drm_device *dev, void *data,
 	entry = kzalloc_obj(*entry);
 	if (!entry) {
 		ret = -ENOMEM;
-		goto err_kzalloc;
+		goto err_fdget;
 	}
 	entry->syncobj = syncobj;
-	entry->ev_fd_ctx = ev_fd_ctx;
+	entry->ev_fd_ctx = no_free_ptr(ev_fd_ctx);
 	entry->point = args->point;
 	entry->flags = args->flags;
 
@@ -1469,8 +1469,6 @@ drm_syncobj_eventfd_ioctl(struct drm_device *dev, void *data,
 
 	return 0;
 
-err_kzalloc:
-	eventfd_ctx_put(ev_fd_ctx);
 err_fdget:
 	drm_syncobj_put(syncobj);
 	return ret;

-- 
2.56.0