+ kcov-refactor-common-handle-id-into-kcov_common_handle_id.patch added to mm-nonmm-unstable branch

+ kcov-refactor-common-handle-id-into-kcov_common_handle_id.patch added to mm-nonmm-unstable branch

[Andrew Morton]

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The patch titled
     Subject: kcov: refactor common handle ID into kcov_common_handle_id
has been added to the -mm mm-nonmm-unstable branch.  Its filename is
     kcov-refactor-common-handle-id-into-kcov_common_handle_id.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/kcov-refactor-common-handle-id-into-kcov_common_handle_id.patch

This patch will later appear in the mm-nonmm-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------
From: Jann Horn <jannh@google.com>
Subject: kcov: refactor common handle ID into kcov_common_handle_id
Date: Thu, 30 Apr 2026 16:15:33 +0200

Store common handle IDs in "struct kcov_common_handle_id", which consumes
no space in non-KCOV builds.

This cleanup removes #ifdef boilerplate code from subsystems that
integrate with KCOV (in particular in usbip_common.h and skbuff.h, see the
diffstat).

This should also make it easier to add KCOV remote coverage to more
subsystems in the future.

Link: https://lore.kernel.org/20260430-kcov-refactor-common-handle-v1-1-23a0c7a0ba38@google.com
Signed-off-by: Jann Horn <jannh@google.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Eugenio Pérez <eperezma@redhat.com>
Cc: Hongren (Zenithal) Zheng <i@zenithal.me>
Cc: Jann Horn <jannh@google.com>
Cc: Jason Wang <jasowang@redhat.com>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Valentina Manea <valentina.manea.m@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 drivers/usb/usbip/usbip_common.h |   29 +----------------------------
 drivers/usb/usbip/vhci_rx.c      |    4 ++--
 drivers/usb/usbip/vhci_sysfs.c   |    2 +-
 drivers/vhost/vhost.h            |    2 +-
 include/linux/kcov.h             |   12 ++++++------
 include/linux/skbuff.h           |   14 +++-----------
 include/linux/types.h            |    6 ++++++
 kernel/kcov.c                    |    6 +++---
 8 files changed, 23 insertions(+), 52 deletions(-)

--- a/drivers/usb/usbip/usbip_common.h~kcov-refactor-common-handle-id-into-kcov_common_handle_id
+++ a/drivers/usb/usbip/usbip_common.h
@@ -282,9 +282,7 @@ struct usbip_device {
 		void (*unusable)(struct usbip_device *);
 	} eh_ops;
 
-#ifdef CONFIG_KCOV
-	u64 kcov_handle;
-#endif
+	struct kcov_common_handle_id kcov_handle;
 };
 
 #define kthread_get_run(threadfn, data, namefmt, ...)			   \
@@ -339,29 +337,4 @@ static inline int interface_to_devnum(st
 	return udev->devnum;
 }
 
-#ifdef CONFIG_KCOV
-
-static inline void usbip_kcov_handle_init(struct usbip_device *ud)
-{
-	ud->kcov_handle = kcov_common_handle();
-}
-
-static inline void usbip_kcov_remote_start(struct usbip_device *ud)
-{
-	kcov_remote_start_common(ud->kcov_handle);
-}
-
-static inline void usbip_kcov_remote_stop(void)
-{
-	kcov_remote_stop();
-}
-
-#else /* CONFIG_KCOV */
-
-static inline void usbip_kcov_handle_init(struct usbip_device *ud) { }
-static inline void usbip_kcov_remote_start(struct usbip_device *ud) { }
-static inline void usbip_kcov_remote_stop(void) { }
-
-#endif /* CONFIG_KCOV */
-
 #endif /* __USBIP_COMMON_H */
--- a/drivers/usb/usbip/vhci_rx.c~kcov-refactor-common-handle-id-into-kcov_common_handle_id
+++ a/drivers/usb/usbip/vhci_rx.c
@@ -261,9 +261,9 @@ int vhci_rx_loop(void *data)
 		if (usbip_event_happened(ud))
 			break;
 
-		usbip_kcov_remote_start(ud);
+		kcov_remote_start_common(ud->kcov_handle);
 		vhci_rx_pdu(ud);
-		usbip_kcov_remote_stop();
+		kcov_remote_stop();
 	}
 
 	return 0;
--- a/drivers/usb/usbip/vhci_sysfs.c~kcov-refactor-common-handle-id-into-kcov_common_handle_id
+++ a/drivers/usb/usbip/vhci_sysfs.c
@@ -425,7 +425,7 @@ static ssize_t attach_store(struct devic
 	vdev->ud.tcp_rx     = tcp_rx;
 	vdev->ud.tcp_tx     = tcp_tx;
 	vdev->ud.status     = VDEV_ST_NOTASSIGNED;
-	usbip_kcov_handle_init(&vdev->ud);
+	vdev->ud.kcov_handle = kcov_common_handle();
 
 	spin_unlock(&vdev->ud.lock);
 	spin_unlock_irqrestore(&vhci->lock, flags);
--- a/drivers/vhost/vhost.h~kcov-refactor-common-handle-id-into-kcov_common_handle_id
+++ a/drivers/vhost/vhost.h
@@ -44,7 +44,7 @@ struct vhost_worker {
 	/* Used to serialize device wide flushing with worker swapping. */
 	struct mutex		mutex;
 	struct llist_head	work_list;
-	u64			kcov_handle;
+	struct kcov_common_handle_id kcov_handle;
 	u32			id;
 	int			attachment_cnt;
 	bool			killed;
--- a/include/linux/kcov.h~kcov-refactor-common-handle-id-into-kcov_common_handle_id
+++ a/include/linux/kcov.h
@@ -43,11 +43,11 @@ do {						\
 /* See Documentation/dev-tools/kcov.rst for usage details. */
 void kcov_remote_start(u64 handle);
 void kcov_remote_stop(void);
-u64 kcov_common_handle(void);
+struct kcov_common_handle_id kcov_common_handle(void);
 
-static inline void kcov_remote_start_common(u64 id)
+static inline void kcov_remote_start_common(struct kcov_common_handle_id id)
 {
-	kcov_remote_start(kcov_remote_handle(KCOV_SUBSYSTEM_COMMON, id));
+	kcov_remote_start(kcov_remote_handle(KCOV_SUBSYSTEM_COMMON, id.val));
 }
 
 static inline void kcov_remote_start_usb(u64 id)
@@ -99,11 +99,11 @@ static inline void kcov_prepare_switch(s
 static inline void kcov_finish_switch(struct task_struct *t) {}
 static inline void kcov_remote_start(u64 handle) {}
 static inline void kcov_remote_stop(void) {}
-static inline u64 kcov_common_handle(void)
+static inline struct kcov_common_handle_id kcov_common_handle(void)
 {
-	return 0;
+	return (struct kcov_common_handle_id){};
 }
-static inline void kcov_remote_start_common(u64 id) {}
+static inline void kcov_remote_start_common(struct kcov_common_handle_id id) {}
 static inline void kcov_remote_start_usb(u64 id) {}
 static inline void kcov_remote_start_usb_softirq(u64 id) {}
 static inline void kcov_remote_stop_softirq(void) {}
--- a/include/linux/skbuff.h~kcov-refactor-common-handle-id-into-kcov_common_handle_id
+++ a/include/linux/skbuff.h
@@ -1082,9 +1082,7 @@ struct sk_buff {
 	__u16			network_header;
 	__u16			mac_header;
 
-#ifdef CONFIG_KCOV
-	u64			kcov_handle;
-#endif
+	struct kcov_common_handle_id kcov_handle;
 
 	); /* end headers group */
 
@@ -5437,20 +5435,14 @@ static inline void skb_reset_csum_not_in
 }
 
 static inline void skb_set_kcov_handle(struct sk_buff *skb,
-				       const u64 kcov_handle)
+				       struct kcov_common_handle_id kcov_handle)
 {
-#ifdef CONFIG_KCOV
 	skb->kcov_handle = kcov_handle;
-#endif
 }
 
-static inline u64 skb_get_kcov_handle(struct sk_buff *skb)
+static inline struct kcov_common_handle_id skb_get_kcov_handle(struct sk_buff *skb)
 {
-#ifdef CONFIG_KCOV
 	return skb->kcov_handle;
-#else
-	return 0;
-#endif
 }
 
 static inline void skb_mark_for_recycle(struct sk_buff *skb)
--- a/include/linux/types.h~kcov-refactor-common-handle-id-into-kcov_common_handle_id
+++ a/include/linux/types.h
@@ -224,6 +224,12 @@ struct ustat {
 	char			f_fpack[6];
 };
 
+struct kcov_common_handle_id {
+#ifdef CONFIG_KCOV
+	u64 val;
+#endif
+};
+
 /**
  * struct callback_head - callback structure for use with RCU and task_work
  * @next: next update requests in a list
--- a/kernel/kcov.c~kcov-refactor-common-handle-id-into-kcov_common_handle_id
+++ a/kernel/kcov.c
@@ -1083,11 +1083,11 @@ void kcov_remote_stop(void)
 EXPORT_SYMBOL(kcov_remote_stop);
 
 /* See the comment before kcov_remote_start() for usage details. */
-u64 kcov_common_handle(void)
+struct kcov_common_handle_id kcov_common_handle(void)
 {
 	if (!in_task())
-		return 0;
-	return current->kcov_handle;
+		return (struct kcov_common_handle_id){ .val = 0 };
+	return (struct kcov_common_handle_id){ .val = current->kcov_handle };
 }
 EXPORT_SYMBOL(kcov_common_handle);
 
_

Patches currently in -mm which might be from jannh@google.com are

kcov-refactor-common-handle-id-into-kcov_common_handle_id.patch