Merge branches 'v3.10/topic/tc2' and 'v3.10/topic/arm64-fvp' of git://git.linaro...

[firefly-linux-kernel-4.4.55.git] / fs / aio.c

diff --git a/fs/aio.c b/fs/aio.c
index 7fe5bdee1630ec7fc89d3bc5d598d427f85e75df..ebd06fd0de89c8e61d7de1712b8c43450347a5c0 100644 (file)
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -141,9 +141,6 @@ static void aio_free_ring(struct kioctx *ctx)
        for (i = 0; i < ctx->nr_pages; i++)
                put_page(ctx->ring_pages[i]);
 
-       if (ctx->mmap_size)
-               vm_munmap(ctx->mmap_base, ctx->mmap_size);
-
        if (ctx->ring_pages && ctx->ring_pages != ctx->internal_pages)
                kfree(ctx->ring_pages);
 }
@@ -322,11 +319,6 @@ static void free_ioctx(struct kioctx *ctx)
 
        aio_free_ring(ctx);
 
-       spin_lock(&aio_nr_lock);
-       BUG_ON(aio_nr - ctx->max_reqs > aio_nr);
-       aio_nr -= ctx->max_reqs;
-       spin_unlock(&aio_nr_lock);
-
        pr_debug("freeing %p\n", ctx);
 
        /*
@@ -431,21 +423,30 @@ static void kill_ioctx_rcu(struct rcu_head *head)
  *     when the processes owning a context have all exited to encourage
  *     the rapid destruction of the kioctx.
  */
-static void kill_ioctx(struct kioctx *ctx)
+static void kill_ioctx(struct mm_struct *mm, struct kioctx *ctx)
 {
        if (!atomic_xchg(&ctx->dead, 1)) {
+               spin_lock(&mm->ioctx_lock);
                hlist_del_rcu(&ctx->list);
-               /* Between hlist_del_rcu() and dropping the initial ref */
-               synchronize_rcu();
+               spin_unlock(&mm->ioctx_lock);
 
                /*
-                * We can't punt to workqueue here because put_ioctx() ->
-                * free_ioctx() will unmap the ringbuffer, and that has to be
-                * done in the original process's context. kill_ioctx_rcu/work()
-                * exist for exit_aio(), as in that path free_ioctx() won't do
-                * the unmap.
+                * It'd be more correct to do this in free_ioctx(), after all
+                * the outstanding kiocbs have finished - but by then io_destroy
+                * has already returned, so io_setup() could potentially return
+                * -EAGAIN with no ioctxs actually in use (as far as userspace
+                *  could tell).
                 */
-               kill_ioctx_work(&ctx->rcu_work);
+               spin_lock(&aio_nr_lock);
+               BUG_ON(aio_nr - ctx->max_reqs > aio_nr);
+               aio_nr -= ctx->max_reqs;
+               spin_unlock(&aio_nr_lock);
+
+               if (ctx->mmap_size)
+                       vm_munmap(ctx->mmap_base, ctx->mmap_size);
+
+               /* Between hlist_del_rcu() and dropping the initial ref */
+               call_rcu(&ctx->rcu_head, kill_ioctx_rcu);
        }
 }
 
@@ -495,10 +496,7 @@ void exit_aio(struct mm_struct *mm)
                 */
                ctx->mmap_size = 0;
 
-               if (!atomic_xchg(&ctx->dead, 1)) {
-                       hlist_del_rcu(&ctx->list);
-                       call_rcu(&ctx->rcu_head, kill_ioctx_rcu);
-               }
+               kill_ioctx(mm, ctx);
        }
 }
 
@@ -856,7 +854,7 @@ SYSCALL_DEFINE2(io_setup, unsigned, nr_events, aio_context_t __user *, ctxp)
        if (!IS_ERR(ioctx)) {
                ret = put_user(ioctx->user_id, ctxp);
                if (ret)
-                       kill_ioctx(ioctx);
+                       kill_ioctx(current->mm, ioctx);
                put_ioctx(ioctx);
        }
 
@@ -874,7 +872,7 @@ SYSCALL_DEFINE1(io_destroy, aio_context_t, ctx)
 {
        struct kioctx *ioctx = lookup_ioctx(ctx);
        if (likely(NULL != ioctx)) {
-               kill_ioctx(ioctx);
+               kill_ioctx(current->mm, ioctx);
                put_ioctx(ioctx);
                return 0;
        }