kcov: refactor common handle ID into kcov_common_handle_id

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>
Acked-by: Jakub Kicinski <kuba@kernel.org>
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>

diff --git a/drivers/usb/usbip/usbip_common.h b/drivers/usb/usbip/usbip_common.h
index 282efca64a01208cf5b189e177ffec53ba9aea00..be4c5e65a7f8c5d8aedf48dc625a1e9bb7144e77 100644 (file)
--- a/drivers/usb/usbip/usbip_common.h
+++ b/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(struct usb_interface *interface)
        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 */

diff --git a/drivers/usb/usbip/vhci_rx.c b/drivers/usb/usbip/vhci_rx.c
index a75f4a898a4127a1844aca28c99fdd4a3b22a5ea..a678e7c8983752b618c3511649f8818be85b7a82 100644 (file)
--- a/drivers/usb/usbip/vhci_rx.c
+++ b/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;

diff --git a/drivers/usb/usbip/vhci_sysfs.c b/drivers/usb/usbip/vhci_sysfs.c
index 5bc8c47788d45039364139eb96d4f45695c3f236..b98d14c43d13d7136ad3b3058a4bbea08447af3b 100644 (file)
--- a/drivers/usb/usbip/vhci_sysfs.c
+++ b/drivers/usb/usbip/vhci_sysfs.c
@@ -425,7 +425,7 @@ static ssize_t attach_store(struct device *dev, struct device_attribute *attr,
        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);

diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h
index 4fe99765c5c73c204a12c13483fb92edcfb97741..0192ade6e749102a083748764f9e8298b2ae79e0 100644 (file)
--- a/drivers/vhost/vhost.h
+++ b/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;

diff --git a/include/linux/kcov.h b/include/linux/kcov.h
index 0143358874b07b6896625395f2b649f63cb298ba..cdb72b3859d87e747c88485b1587b4f5f136bff5 100644 (file)
--- a/include/linux/kcov.h
+++ b/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(struct task_struct *t) {}
 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) {}

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 2bcf78a4de7b9edb0d1342319d4340c0a9997eeb..a3fe418f7ced8235bf4b527051a1a9d16d1a1acf 100644 (file)
--- a/include/linux/skbuff.h
+++ b/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_inet(struct sk_buff *skb)
 }
 
 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)

diff --git a/include/linux/types.h b/include/linux/types.h
index 608050dbca6a7c374dfc42b6aa6f40a234c8287c..93166b0b0617ad4ab951b7d7e20d3e35727121ec 100644 (file)
--- a/include/linux/types.h
+++ b/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

diff --git a/kernel/kcov.c b/kernel/kcov.c
index 0b369e88c7c9bec04b822ff4f2f4b2fed4a28b9c..a43e33a28adb9872827ced4904fabd9783a74cb6 100644 (file)
--- a/kernel/kcov.c
+++ b/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);