| Message ID | 20200415004353.130248-2-walken@google.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Add a new mmap locking API wrapping mmap_sem calls | expand |
On Tue, 14 Apr 2020, Michel Lespinasse wrote: >This change wraps the existing mmap_sem related rwsem calls into a new >mmap locking API. There are two justifications for the new API: > >- At first, it provides an easy hooking point to instrument mmap_sem > locking latencies independently of any other rwsems. > >- In the future, it may be a starting point for replacing the rwsem > implementation with a different one, such as range locks. > >Signed-off-by: Michel Lespinasse <walken@google.com> >Reviewed-by: Daniel Jordan <daniel.m.jordan@oracle.com> Reviewed-by: Davidlohr Bueso <dbueso@suse.de> With one observation below. >+static inline void mmap_downgrade_write_lock(struct mm_struct *mm) >+{ >+ downgrade_write(&mm->mmap_sem); >+} Shouldn't this really be just mmap_downgrade_write()? In locking normally don't add the _lock at the end as it implies the operation of acquiring the lock. Thanks, Davidlohr
On Mon, Apr 20, 2020 at 12:51 PM Davidlohr Bueso <dave@stgolabs.net> wrote: > With one observation below. > > >+static inline void mmap_downgrade_write_lock(struct mm_struct *mm) > >+{ > >+ downgrade_write(&mm->mmap_sem); > >+} > > Shouldn't this really be just mmap_downgrade_write()? In locking > normally don't add the _lock at the end as it implies the operation > of acquiring the lock. Hmmm, I see your point. Actually here the operation is downgrade, so arguably the name should be mmap_write_downgrade ? I'm not sure I like the name though, as it does not make it entirely obvious that the function is a locking primitive.
diff --git a/include/linux/mm.h b/include/linux/mm.h index 5a323422d783..051ec782bdbb 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -15,6 +15,7 @@ #include <linux/atomic.h> #include <linux/debug_locks.h> #include <linux/mm_types.h> +#include <linux/mmap_lock.h> #include <linux/range.h> #include <linux/pfn.h> #include <linux/percpu-refcount.h> diff --git a/include/linux/mmap_lock.h b/include/linux/mmap_lock.h new file mode 100644 index 000000000000..8b5a3cd56118 --- /dev/null +++ b/include/linux/mmap_lock.h @@ -0,0 +1,54 @@ +#ifndef _LINUX_MMAP_LOCK_H +#define _LINUX_MMAP_LOCK_H + +static inline void mmap_init_lock(struct mm_struct *mm) +{ + init_rwsem(&mm->mmap_sem); +} + +static inline void mmap_write_lock(struct mm_struct *mm) +{ + down_write(&mm->mmap_sem); +} + +static inline int mmap_write_lock_killable(struct mm_struct *mm) +{ + return down_write_killable(&mm->mmap_sem); +} + +static inline bool mmap_write_trylock(struct mm_struct *mm) +{ + return down_write_trylock(&mm->mmap_sem) != 0; +} + +static inline void mmap_write_unlock(struct mm_struct *mm) +{ + up_write(&mm->mmap_sem); +} + +static inline void mmap_downgrade_write_lock(struct mm_struct *mm) +{ + downgrade_write(&mm->mmap_sem); +} + +static inline void mmap_read_lock(struct mm_struct *mm) +{ + down_read(&mm->mmap_sem); +} + +static inline int mmap_read_lock_killable(struct mm_struct *mm) +{ + return down_read_killable(&mm->mmap_sem); +} + +static inline bool mmap_read_trylock(struct mm_struct *mm) +{ + return down_read_trylock(&mm->mmap_sem) != 0; +} + +static inline void mmap_read_unlock(struct mm_struct *mm) +{ + up_read(&mm->mmap_sem); +} + +#endif /* _LINUX_MMAP_LOCK_H */