From: Jason Gunthorpe <jgg@xxxxxxxxxxxx>
Only the function calls are stubbed out with static inlines that always
fail. This is the standard way to write a header for an optional component
and makes it easier for drivers that only optionally need HMM_MIRROR.
Reviewed-by: Jérôme Glisse <jglisse@xxxxxxxxxx>
Tested-by: Ralph Campbell <rcampbell@xxxxxxxxxx>
Signed-off-by: Jason Gunthorpe <jgg@xxxxxxxxxxxx>
---
include/linux/hmm.h | 59 ++++++++++++++++++++++++++++++++++++---------
kernel/fork.c | 1 -
2 files changed, 47 insertions(+), 13 deletions(-)
diff --git a/include/linux/hmm.h b/include/linux/hmm.h
index fbb35c78637e57..cb69bf10dc788c 100644
--- a/include/linux/hmm.h
+++ b/include/linux/hmm.h
@@ -62,8 +62,6 @@
#include <linux/kconfig.h>
#include <asm/pgtable.h>
-#ifdef CONFIG_HMM_MIRROR
-
#include <linux/device.h>
#include <linux/migrate.h>
#include <linux/memremap.h>
@@ -374,6 +372,15 @@ struct hmm_mirror {
struct list_head list;
};
+/*
+ * Retry fault if non-blocking, drop mmap_sem and return -EAGAIN in that case.
+ */
+#define HMM_FAULT_ALLOW_RETRY (1 << 0)
+
+/* Don't fault in missing PTEs, just snapshot the current state. */
+#define HMM_FAULT_SNAPSHOT (1 << 1)
+
+#ifdef CONFIG_HMM_MIRROR
int hmm_mirror_register(struct hmm_mirror *mirror, struct mm_struct *mm);
void hmm_mirror_unregister(struct hmm_mirror *mirror);
@@ -383,14 +390,6 @@ void hmm_mirror_unregister(struct hmm_mirror *mirror);
int hmm_range_register(struct hmm_range *range, struct hmm_mirror *mirror);
void hmm_range_unregister(struct hmm_range *range);
-/*
- * Retry fault if non-blocking, drop mmap_sem and return -EAGAIN in that case.
- */
-#define HMM_FAULT_ALLOW_RETRY (1 << 0)
-
-/* Don't fault in missing PTEs, just snapshot the current state. */
-#define HMM_FAULT_SNAPSHOT (1 << 1)
-
long hmm_range_fault(struct hmm_range *range, unsigned int flags);
long hmm_range_dma_map(struct hmm_range *range,
@@ -401,6 +400,44 @@ long hmm_range_dma_unmap(struct hmm_range *range,
struct device *device,
dma_addr_t *daddrs,
bool dirty);
+#else
+int hmm_mirror_register(struct hmm_mirror *mirror, struct mm_struct *mm)
+{
+ return -EOPNOTSUPP;
+}
+
+void hmm_mirror_unregister(struct hmm_mirror *mirror)
+{
+}
+
+int hmm_range_register(struct hmm_range *range, struct hmm_mirror *mirror)
+{
+ return -EOPNOTSUPP;
+}
+
+void hmm_range_unregister(struct hmm_range *range)
+{
+}
+
+static inline long hmm_range_fault(struct hmm_range *range, unsigned int flags)
+{
+ return -EOPNOTSUPP;
+}
+
+static inline long hmm_range_dma_map(struct hmm_range *range,
+ struct device *device, dma_addr_t *daddrs,
+ unsigned int flags)
+{
+ return -EOPNOTSUPP;
+}
+
+static inline long hmm_range_dma_unmap(struct hmm_range *range,
+ struct device *device,
+ dma_addr_t *daddrs, bool dirty)
+{
+ return -EOPNOTSUPP;
+}
+#endif
/*
* HMM_RANGE_DEFAULT_TIMEOUT - default timeout (ms) when waiting for a range
@@ -411,6 +448,4 @@ long hmm_range_dma_unmap(struct hmm_range *range,
*/
#define HMM_RANGE_DEFAULT_TIMEOUT 1000
-#endif /* IS_ENABLED(CONFIG_HMM_MIRROR) */
-
#endif /* LINUX_HMM_H */
diff --git a/kernel/fork.c b/kernel/fork.c
index bcdf5312521036..ca39cfc404e3db 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -40,7 +40,6 @@
#include <linux/binfmts.h>
#include <linux/mman.h>
#include <linux/mmu_notifier.h>
-#include <linux/hmm.h>
#include <linux/fs.h>
#include <linux/mm.h>
#include <linux/vmacache.h>
--
2.24.0
