On 10/28/19 1:10 PM, Jason Gunthorpe wrote:
> From: Jason Gunthorpe <jgg@xxxxxxxxxxxx>
>
> Now that we have KERNEL_HEADER_TEST all headers are generally compile
> tested, so relying on makefile tricks to avoid compiling code that depends
> on CONFIG_MMU_NOTIFIER is more annoying.
>
> Instead follow the usual pattern and provide most of the header with only
> the functions stubbed out when CONFIG_MMU_NOTIFIER is disabled. This
> ensures code compiles no matter what the config setting is.
>
> While here, struct mmu_notifier_mm is private to mmu_notifier.c, move it.
and correct a minor spelling error in a comment. Good. :)
>
> Reviewed-by: Jérôme Glisse <jglisse@xxxxxxxxxx>
> Signed-off-by: Jason Gunthorpe <jgg@xxxxxxxxxxxx>
> ---
> include/linux/mmu_notifier.h | 46 +++++++++++++-----------------------
> mm/mmu_notifier.c | 13 ++++++++++
> 2 files changed, 30 insertions(+), 29 deletions(-)
>
Because this is correct as-is, you can add:
Reviewed-by: John Hubbard <jhubbard@xxxxxxxxxx>
...whether or not you take the following recommendation, which is:
you've only done part of the job of making struct mmu_notifier_mm
private to mmu_notifier.c. There's more:
* struct mmu_notifier_mm is referred to in two places now: mm_types.h
and (still) mmu_notifier.h. Therefore:
a) Move the last two traces of it out of mmu_notifier.h, and
b) Put a forward declaration in mm_types.h, which is where it
belongs because that's where it's referred to.
So if you apply this incremental patch on top, I think it's where
you want to be:
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index 2222fa795284..df93a3cc0da9 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -25,6 +25,7 @@
struct address_space;
struct mem_cgroup;
+struct mmu_notifier_mm;
/*
* Each physical page in the system has a struct page associated with
diff --git a/include/linux/mmu_notifier.h b/include/linux/mmu_notifier.h
index 51b92ba013dd..84efd2c51f5c 100644
--- a/include/linux/mmu_notifier.h
+++ b/include/linux/mmu_notifier.h
@@ -8,7 +8,6 @@
#include <linux/srcu.h>
#include <linux/interval_tree.h>
-struct mmu_notifier_mm;
struct mmu_notifier;
struct mmu_notifier_range;
struct mmu_range_notifier;
@@ -263,10 +262,7 @@ struct mmu_notifier_range {
enum mmu_notifier_event event;
};
-static inline int mm_has_notifiers(struct mm_struct *mm)
-{
- return unlikely(mm->mmu_notifier_mm);
-}
+int mm_has_notifiers(struct mm_struct *mm);
struct mmu_notifier *mmu_notifier_get_locked(const struct mmu_notifier_ops *ops,
struct mm_struct *mm);
@@ -477,10 +473,7 @@ static inline void mmu_notifier_invalidate_range(struct mm_struct *mm,
__mmu_notifier_invalidate_range(mm, start, end);
}
-static inline void mmu_notifier_mm_init(struct mm_struct *mm)
-{
- mm->mmu_notifier_mm = NULL;
-}
+void mmu_notifier_mm_init(struct mm_struct *mm);
static inline void mmu_notifier_mm_destroy(struct mm_struct *mm)
{
diff --git a/mm/mmu_notifier.c b/mm/mmu_notifier.c
index 2b7485919ecf..107f9406a92d 100644
--- a/mm/mmu_notifier.c
+++ b/mm/mmu_notifier.c
@@ -47,6 +47,16 @@ struct mmu_notifier_mm {
struct hlist_head deferred_list;
};
+int mm_has_notifiers(struct mm_struct *mm)
+{
+ return unlikely(mm->mmu_notifier_mm);
+}
+
+void mmu_notifier_mm_init(struct mm_struct *mm)
+{
+ mm->mmu_notifier_mm = NULL;
+}
+
/*
* This is a collision-retry read-side/write-side 'lock', a lot like a
* seqcount, however this allows multiple write-sides to hold it at
thanks,
John Hubbard
NVIDIA
> diff --git a/include/linux/mmu_notifier.h b/include/linux/mmu_notifier.h
> index 1bd8e6a09a3c27..12bd603d318ce7 100644
> --- a/include/linux/mmu_notifier.h
> +++ b/include/linux/mmu_notifier.h
> @@ -7,8 +7,9 @@
> #include <linux/mm_types.h>
> #include <linux/srcu.h>
>
> +struct mmu_notifier_mm;
> struct mmu_notifier;
> -struct mmu_notifier_ops;
> +struct mmu_notifier_range;
>
> /**
> * enum mmu_notifier_event - reason for the mmu notifier callback
> @@ -40,36 +41,8 @@ enum mmu_notifier_event {
> MMU_NOTIFY_SOFT_DIRTY,
> };
>
> -#ifdef CONFIG_MMU_NOTIFIER
> -
> -#ifdef CONFIG_LOCKDEP
> -extern struct lockdep_map __mmu_notifier_invalidate_range_start_map;
> -#endif
> -
> -/*
> - * The mmu notifier_mm structure is allocated and installed in
> - * mm->mmu_notifier_mm inside the mm_take_all_locks() protected
> - * critical section and it's released only when mm_count reaches zero
> - * in mmdrop().
> - */
> -struct mmu_notifier_mm {
> - /* all mmu notifiers registerd in this mm are queued in this list */
> - struct hlist_head list;
> - /* to serialize the list modifications and hlist_unhashed */
> - spinlock_t lock;
> -};
> -
> #define MMU_NOTIFIER_RANGE_BLOCKABLE (1 << 0)
>
> -struct mmu_notifier_range {
> - struct vm_area_struct *vma;
> - struct mm_struct *mm;
> - unsigned long start;
> - unsigned long end;
> - unsigned flags;
> - enum mmu_notifier_event event;
> -};
> -
> struct mmu_notifier_ops {
> /*
> * Called either by mmu_notifier_unregister or when the mm is
> @@ -249,6 +222,21 @@ struct mmu_notifier {
> unsigned int users;
> };
>
> +#ifdef CONFIG_MMU_NOTIFIER
> +
> +#ifdef CONFIG_LOCKDEP
> +extern struct lockdep_map __mmu_notifier_invalidate_range_start_map;
> +#endif
> +
> +struct mmu_notifier_range {
> + struct vm_area_struct *vma;
> + struct mm_struct *mm;
> + unsigned long start;
> + unsigned long end;
> + unsigned flags;
> + enum mmu_notifier_event event;
> +};
> +
> static inline int mm_has_notifiers(struct mm_struct *mm)
> {
> return unlikely(mm->mmu_notifier_mm);
> diff --git a/mm/mmu_notifier.c b/mm/mmu_notifier.c
> index 7fde88695f35d6..367670cfd02b7b 100644
> --- a/mm/mmu_notifier.c
> +++ b/mm/mmu_notifier.c
> @@ -27,6 +27,19 @@ struct lockdep_map __mmu_notifier_invalidate_range_start_map = {
> };
> #endif
>
> +/*
> + * The mmu notifier_mm structure is allocated and installed in
> + * mm->mmu_notifier_mm inside the mm_take_all_locks() protected
> + * critical section and it's released only when mm_count reaches zero
> + * in mmdrop().
> + */
> +struct mmu_notifier_mm {
> + /* all mmu notifiers registered in this mm are queued in this list */
> + struct hlist_head list;
> + /* to serialize the list modifications and hlist_unhashed */
> + spinlock_t lock;
> +};
> +
> /*
> * This function can't run concurrently against mmu_notifier_register
> * because mm->mm_users > 0 during mmu_notifier_register and exit_mmap
>
