Commit d0f278c1 authored by Linus Torvalds's avatar Linus Torvalds

Merge git://git.kvack.org/~bcrl/aio-next

Pull aio fixes from Benjamin LaHaise.

* git://git.kvack.org/~bcrl/aio-next:
  aio: nullify aio->ring_pages after freeing it
  aio: prevent double free in ioctx_alloc
  aio: Fix a trinity splat
parents 533db9b3 ddb8c45b
......@@ -80,6 +80,8 @@ struct kioctx {
struct percpu_ref users;
atomic_t dead;
struct percpu_ref reqs;
unsigned long user_id;
struct __percpu kioctx_cpu *cpu;
......@@ -107,7 +109,6 @@ struct kioctx {
struct page **ring_pages;
long nr_pages;
struct rcu_head rcu_head;
struct work_struct free_work;
struct {
......@@ -250,8 +251,10 @@ static void aio_free_ring(struct kioctx *ctx)
put_aio_ring_file(ctx);
if (ctx->ring_pages && ctx->ring_pages != ctx->internal_pages)
if (ctx->ring_pages && ctx->ring_pages != ctx->internal_pages) {
kfree(ctx->ring_pages);
ctx->ring_pages = NULL;
}
}
static int aio_ring_mmap(struct file *file, struct vm_area_struct *vma)
......@@ -463,26 +466,34 @@ static int kiocb_cancel(struct kioctx *ctx, struct kiocb *kiocb)
return cancel(kiocb);
}
static void free_ioctx_rcu(struct rcu_head *head)
static void free_ioctx(struct work_struct *work)
{
struct kioctx *ctx = container_of(head, struct kioctx, rcu_head);
struct kioctx *ctx = container_of(work, struct kioctx, free_work);
pr_debug("freeing %p\n", ctx);
aio_free_ring(ctx);
free_percpu(ctx->cpu);
kmem_cache_free(kioctx_cachep, ctx);
}
static void free_ioctx_reqs(struct percpu_ref *ref)
{
struct kioctx *ctx = container_of(ref, struct kioctx, reqs);
INIT_WORK(&ctx->free_work, free_ioctx);
schedule_work(&ctx->free_work);
}
/*
* When this function runs, the kioctx has been removed from the "hash table"
* and ctx->users has dropped to 0, so we know no more kiocbs can be submitted -
* now it's safe to cancel any that need to be.
*/
static void free_ioctx(struct work_struct *work)
static void free_ioctx_users(struct percpu_ref *ref)
{
struct kioctx *ctx = container_of(work, struct kioctx, free_work);
struct aio_ring *ring;
struct kioctx *ctx = container_of(ref, struct kioctx, users);
struct kiocb *req;
unsigned cpu, avail;
DEFINE_WAIT(wait);
spin_lock_irq(&ctx->ctx_lock);
......@@ -496,54 +507,8 @@ static void free_ioctx(struct work_struct *work)
spin_unlock_irq(&ctx->ctx_lock);
for_each_possible_cpu(cpu) {
struct kioctx_cpu *kcpu = per_cpu_ptr(ctx->cpu, cpu);
atomic_add(kcpu->reqs_available, &ctx->reqs_available);
kcpu->reqs_available = 0;
}
while (1) {
prepare_to_wait(&ctx->wait, &wait, TASK_UNINTERRUPTIBLE);
ring = kmap_atomic(ctx->ring_pages[0]);
avail = (ring->head <= ring->tail)
? ring->tail - ring->head
: ctx->nr_events - ring->head + ring->tail;
atomic_add(avail, &ctx->reqs_available);
ring->head = ring->tail;
kunmap_atomic(ring);
if (atomic_read(&ctx->reqs_available) >= ctx->nr_events - 1)
break;
schedule();
}
finish_wait(&ctx->wait, &wait);
WARN_ON(atomic_read(&ctx->reqs_available) > ctx->nr_events - 1);
aio_free_ring(ctx);
pr_debug("freeing %p\n", ctx);
/*
* Here the call_rcu() is between the wait_event() for reqs_active to
* hit 0, and freeing the ioctx.
*
* aio_complete() decrements reqs_active, but it has to touch the ioctx
* after to issue a wakeup so we use rcu.
*/
call_rcu(&ctx->rcu_head, free_ioctx_rcu);
}
static void free_ioctx_ref(struct percpu_ref *ref)
{
struct kioctx *ctx = container_of(ref, struct kioctx, users);
INIT_WORK(&ctx->free_work, free_ioctx);
schedule_work(&ctx->free_work);
percpu_ref_kill(&ctx->reqs);
percpu_ref_put(&ctx->reqs);
}
static int ioctx_add_table(struct kioctx *ctx, struct mm_struct *mm)
......@@ -602,6 +567,16 @@ static int ioctx_add_table(struct kioctx *ctx, struct mm_struct *mm)
}
}
static void aio_nr_sub(unsigned nr)
{
spin_lock(&aio_nr_lock);
if (WARN_ON(aio_nr - nr > aio_nr))
aio_nr = 0;
else
aio_nr -= nr;
spin_unlock(&aio_nr_lock);
}
/* ioctx_alloc
* Allocates and initializes an ioctx. Returns an ERR_PTR if it failed.
*/
......@@ -639,8 +614,11 @@ static struct kioctx *ioctx_alloc(unsigned nr_events)
ctx->max_reqs = nr_events;
if (percpu_ref_init(&ctx->users, free_ioctx_ref))
goto out_freectx;
if (percpu_ref_init(&ctx->users, free_ioctx_users))
goto err;
if (percpu_ref_init(&ctx->reqs, free_ioctx_reqs))
goto err;
spin_lock_init(&ctx->ctx_lock);
spin_lock_init(&ctx->completion_lock);
......@@ -651,10 +629,10 @@ static struct kioctx *ioctx_alloc(unsigned nr_events)
ctx->cpu = alloc_percpu(struct kioctx_cpu);
if (!ctx->cpu)
goto out_freeref;
goto err;
if (aio_setup_ring(ctx) < 0)
goto out_freepcpu;
goto err;
atomic_set(&ctx->reqs_available, ctx->nr_events - 1);
ctx->req_batch = (ctx->nr_events - 1) / (num_possible_cpus() * 4);
......@@ -666,7 +644,8 @@ static struct kioctx *ioctx_alloc(unsigned nr_events)
if (aio_nr + nr_events > (aio_max_nr * 2UL) ||
aio_nr + nr_events < aio_nr) {
spin_unlock(&aio_nr_lock);
goto out_cleanup;
err = -EAGAIN;
goto err;
}
aio_nr += ctx->max_reqs;
spin_unlock(&aio_nr_lock);
......@@ -675,23 +654,18 @@ static struct kioctx *ioctx_alloc(unsigned nr_events)
err = ioctx_add_table(ctx, mm);
if (err)
goto out_cleanup_put;
goto err_cleanup;
pr_debug("allocated ioctx %p[%ld]: mm=%p mask=0x%x\n",
ctx, ctx->user_id, mm, ctx->nr_events);
return ctx;
out_cleanup_put:
percpu_ref_put(&ctx->users);
out_cleanup:
err = -EAGAIN;
aio_free_ring(ctx);
out_freepcpu:
err_cleanup:
aio_nr_sub(ctx->max_reqs);
err:
free_percpu(ctx->cpu);
out_freeref:
free_percpu(ctx->reqs.pcpu_count);
free_percpu(ctx->users.pcpu_count);
out_freectx:
put_aio_ring_file(ctx);
kmem_cache_free(kioctx_cachep, ctx);
pr_debug("error allocating ioctx %d\n", err);
return ERR_PTR(err);
......@@ -726,10 +700,7 @@ static void kill_ioctx(struct mm_struct *mm, struct kioctx *ctx)
* -EAGAIN with no ioctxs actually in use (as far as userspace
* could tell).
*/
spin_lock(&aio_nr_lock);
BUG_ON(aio_nr - ctx->max_reqs > aio_nr);
aio_nr -= ctx->max_reqs;
spin_unlock(&aio_nr_lock);
aio_nr_sub(ctx->max_reqs);
if (ctx->mmap_size)
vm_munmap(ctx->mmap_base, ctx->mmap_size);
......@@ -861,6 +832,8 @@ static inline struct kiocb *aio_get_req(struct kioctx *ctx)
if (unlikely(!req))
goto out_put;
percpu_ref_get(&ctx->reqs);
req->ki_ctx = ctx;
return req;
out_put:
......@@ -930,12 +903,6 @@ void aio_complete(struct kiocb *iocb, long res, long res2)
return;
}
/*
* Take rcu_read_lock() in case the kioctx is being destroyed, as we
* need to issue a wakeup after incrementing reqs_available.
*/
rcu_read_lock();
if (iocb->ki_list.next) {
unsigned long flags;
......@@ -1010,7 +977,7 @@ void aio_complete(struct kiocb *iocb, long res, long res2)
if (waitqueue_active(&ctx->wait))
wake_up(&ctx->wait);
rcu_read_unlock();
percpu_ref_put(&ctx->reqs);
}
EXPORT_SYMBOL(aio_complete);
......@@ -1421,6 +1388,7 @@ static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb,
return 0;
out_put_req:
put_reqs_available(ctx, 1);
percpu_ref_put(&ctx->reqs);
kiocb_free(req);
return ret;
}
......
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