git: a200c8e51cdb - main - linuxkpi: Add eventfd_*()
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Date: Sun, 25 Jan 2026 16:16:44 UTC
The branch main has been updated by dumbbell:
URL: https://cgit.FreeBSD.org/src/commit/?id=a200c8e51cdb4586ad2eb20d2b45ba367f00beaf
commit a200c8e51cdb4586ad2eb20d2b45ba367f00beaf
Author: Jean-Sébastien Pédron <dumbbell@FreeBSD.org>
AuthorDate: 2025-05-26 18:12:40 +0000
Commit: Jean-Sébastien Pédron <dumbbell@FreeBSD.org>
CommitDate: 2026-01-25 16:04:44 +0000
linuxkpi: Add eventfd_*()
Add <linux/eventfd.h> and expose the `eventfd_*()` API. This is used by
DRM drivers for some time, but the code was commented out so far.
Note that Linux uses `struct eventfd_ctx`, but FreeBSD defines `struct
eventfd`. We define `eventfd_ctx` as a synonym to `eventfd`.
Reviewed by: christos, markj
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D50853
---
sys/compat/linuxkpi/common/include/linux/eventfd.h | 54 +++++++++++++++++++
sys/compat/linuxkpi/common/src/linux_eventfd.c | 63 ++++++++++++++++++++++
sys/compat/linuxkpi/dummy/include/linux/eventfd.h | 0
sys/conf/files | 2 +
sys/modules/linuxkpi/Makefile | 1 +
5 files changed, 120 insertions(+)
diff --git a/sys/compat/linuxkpi/common/include/linux/eventfd.h b/sys/compat/linuxkpi/common/include/linux/eventfd.h
new file mode 100644
index 000000000000..d167d4b7d189
--- /dev/null
+++ b/sys/compat/linuxkpi/common/include/linux/eventfd.h
@@ -0,0 +1,54 @@
+/*-
+ * Copyright (c) 2025 The FreeBSD Foundation
+ * Copyright (c) 2025 Jean-Sébastien Pédron
+ *
+ * This software was developed by Jean-Sébastien Pédron under sponsorship
+ * from the FreeBSD Foundation.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#ifndef _LINUXKPI_LINUX_EVENTFD_H_
+#define _LINUXKPI_LINUX_EVENTFD_H_
+
+#include <sys/eventfd.h>
+
+#include <linux/wait.h>
+#include <linux/err.h>
+#include <linux/percpu-defs.h>
+#include <linux/percpu.h>
+#include <linux/sched.h>
+
+/*
+ * Linux uses `struct eventfd_ctx`, but FreeBSD defines `struct eventfd`. Here,
+ * we define a synonym to the FreeBSD structure. This allows to keep Linux code
+ * unmodified.
+ */
+#define eventfd_ctx eventfd
+
+#define eventfd_ctx_fdget lkpi_eventfd_ctx_fdget
+struct eventfd_ctx *lkpi_eventfd_ctx_fdget(int fd);
+
+#define eventfd_ctx_put lkpi_eventfd_ctx_put
+void lkpi_eventfd_ctx_put(struct eventfd_ctx *ctx);
+
+#endif /* _LINUXKPI_LINUX_EVENTFD_H_ */
diff --git a/sys/compat/linuxkpi/common/src/linux_eventfd.c b/sys/compat/linuxkpi/common/src/linux_eventfd.c
new file mode 100644
index 000000000000..126c6c54b9a5
--- /dev/null
+++ b/sys/compat/linuxkpi/common/src/linux_eventfd.c
@@ -0,0 +1,63 @@
+/*-
+ * Copyright (c) 2025 The FreeBSD Foundation
+ * Copyright (c) 2025 Jean-Sébastien Pédron
+ *
+ * This software was developed by Jean-Sébastien Pédron under sponsorship
+ * from the FreeBSD Foundation.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <sys/param.h>
+#include <sys/file.h>
+#include <sys/filedesc.h>
+
+#include <linux/eventfd.h>
+
+struct eventfd_ctx *
+lkpi_eventfd_ctx_fdget(int fd)
+{
+ struct file *fp;
+ struct eventfd_ctx *ctx;
+
+ /* Lookup file pointer by file descriptor index. */
+ if (fget_unlocked(curthread, fd, &cap_no_rights, &fp) != 0)
+ return (ERR_PTR(-EBADF));
+
+ /*
+ * eventfd_get() bumps the refcount, so we can safely release the
+ * reference on the file itself afterwards.
+ */
+ ctx = eventfd_get(fp);
+ fdrop(fp, curthread);
+
+ if (ctx == NULL)
+ return (ERR_PTR(-EBADF));
+
+ return (ctx);
+}
+
+void
+lkpi_eventfd_ctx_put(struct eventfd_ctx *ctx)
+{
+ eventfd_put(ctx);
+}
diff --git a/sys/compat/linuxkpi/dummy/include/linux/eventfd.h b/sys/compat/linuxkpi/dummy/include/linux/eventfd.h
deleted file mode 100644
index e69de29bb2d1..000000000000
diff --git a/sys/conf/files b/sys/conf/files
index 5f8c9379ddf3..66b84fea1bc0 100644
--- a/sys/conf/files
+++ b/sys/conf/files
@@ -4662,6 +4662,8 @@ compat/linuxkpi/common/src/linux_dmi.c optional compat_linuxkpi \
compile-with "${LINUXKPI_C}"
compat/linuxkpi/common/src/linux_domain.c optional compat_linuxkpi \
compile-with "${LINUXKPI_C}"
+compat/linuxkpi/common/src/linux_eventfd.c optional compat_linuxkpi \
+ compile-with "${LINUXKPI_C}"
compat/linuxkpi/common/src/linux_firmware.c optional compat_linuxkpi \
compile-with "${LINUXKPI_C}"
compat/linuxkpi/common/src/linux_folio.c optional compat_linuxkpi \
diff --git a/sys/modules/linuxkpi/Makefile b/sys/modules/linuxkpi/Makefile
index 77d73f19075a..2090fe76d857 100644
--- a/sys/modules/linuxkpi/Makefile
+++ b/sys/modules/linuxkpi/Makefile
@@ -6,6 +6,7 @@ SRCS= linux_compat.c \
linux_devres.c \
linux_dmi.c \
linux_domain.c \
+ linux_eventfd.c \
linux_firmware.c \
linux_folio.c \
linux_fpu.c \