2014-02-18 15:35:49

by Mateusz Guzik

[permalink] [raw]
Subject: [PATCH] aio: simplify exit_aio

Since there are no other callers which can manipulate ioctx_table at
this stage it is not necessary to reload table pointer each time nor
to traverse it under rcu_read_lock

While here convert the loop to more readable for () and fix the
comment (aio_free_ring -> kill_ioctx).

Signed-off-by: Mateusz Guzik <[email protected]>
---
fs/aio.c | 33 +++++++++++++++------------------
1 file changed, 15 insertions(+), 18 deletions(-)

diff --git a/fs/aio.c b/fs/aio.c
index 062a5f6..0701181 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -766,38 +766,35 @@ void exit_aio(struct mm_struct *mm)
{
struct kioctx_table *table;
struct kioctx *ctx;
- unsigned i = 0;
+ unsigned i;

- while (1) {
- rcu_read_lock();
- table = rcu_dereference(mm->ioctx_table);
-
- do {
- if (!table || i >= table->nr) {
- rcu_read_unlock();
- rcu_assign_pointer(mm->ioctx_table, NULL);
- if (table)
- kfree(table);
- return;
- }
+ rcu_read_lock();
+ table = rcu_dereference(mm->ioctx_table);
+ rcu_read_unlock();

- ctx = table->table[i++];
- } while (!ctx);
+ if (!table)
+ return;

- rcu_read_unlock();
+ for (i = 0; i < table->nr; i++) {
+ ctx = table->table[i];
+ if (!ctx)
+ continue;

/*
* We don't need to bother with munmap() here -
* exit_mmap(mm) is coming and it'll unmap everything.
- * Since aio_free_ring() uses non-zero ->mmap_size
+ * Since kill_ioctx() uses non-zero ->mmap_size
* as indicator that it needs to unmap the area,
- * just set it to 0; aio_free_ring() is the only
+ * just set it to 0; kill_ioctx() is the only
* place that uses ->mmap_size, so it's safe.
*/
ctx->mmap_size = 0;

kill_ioctx(mm, ctx);
}
+
+ rcu_assign_pointer(mm->ioctx_table, NULL);
+ kfree(table);
}

static void put_reqs_available(struct kioctx *ctx, unsigned nr)
--
1.8.3.1