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| author | Peter Zijlstra <peterz@infradead.org> | 2020-03-04 13:02:41 +0100 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2020-03-06 11:06:18 +0100 |
| commit | 222993395ed38f3751287f4bd82ef46b3eb3a66d (patch) | |
| tree | 6b3dd02dcc21765cbeacb30b316b67f4d8101ed6 | |
| parent | 3867913c45b478dec7f9a60b950ad88a14e2a748 (diff) | |
| download | linux-222993395ed38f3751287f4bd82ef46b3eb3a66d.tar.gz linux-222993395ed38f3751287f4bd82ef46b3eb3a66d.tar.bz2 linux-222993395ed38f3751287f4bd82ef46b3eb3a66d.zip | |
futex: Remove pointless mmgrap() + mmdrop()
We always set 'key->private.mm' to 'current->mm', getting an extra
reference on 'current->mm' is quite pointless, because as long as the
task is blocked it isn't going to go away.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
| -rw-r--r-- | kernel/futex.c | 14 |
1 files changed, 1 insertions, 13 deletions
diff --git a/kernel/futex.c b/kernel/futex.c index e14f7cd45dbd..3463c916605a 100644 --- a/kernel/futex.c +++ b/kernel/futex.c @@ -331,17 +331,6 @@ static void compat_exit_robust_list(struct task_struct *curr); static inline void compat_exit_robust_list(struct task_struct *curr) { } #endif -static inline void futex_get_mm(union futex_key *key) -{ - mmgrab(key->private.mm); - /* - * Ensure futex_get_mm() implies a full barrier such that - * get_futex_key() implies a full barrier. This is relied upon - * as smp_mb(); (B), see the ordering comment above. - */ - smp_mb__after_atomic(); -} - /* * Reflects a new waiter being added to the waitqueue. */ @@ -432,7 +421,7 @@ static void get_futex_key_refs(union futex_key *key) smp_mb(); /* explicit smp_mb(); (B) */ break; case FUT_OFF_MMSHARED: - futex_get_mm(key); /* implies smp_mb(); (B) */ + smp_mb(); /* explicit smp_mb(); (B) */ break; default: /* @@ -465,7 +454,6 @@ static void drop_futex_key_refs(union futex_key *key) case FUT_OFF_INODE: break; case FUT_OFF_MMSHARED: - mmdrop(key->private.mm); break; } } |