Merge remote-tracking branch 'linus/master' into patchwork

There are some patches that depends on media-v3.16-rc6.
So, merge back from upstream before applying them.

* linus/master: (1123 commits)
  drm/nouveau: ltc/gf100-: fix cbc issues on certain boards
  drm/bochs: add missing drm_connector_register call
  drm/cirrus: add missing drm_connector_register call
  staging: vt6655: buffer overflow in ioctl
  USB: storage: Add quirks for Entrega/Xircom USB to SCSI converters
  USB: storage: Add quirk for Ariston Technologies iConnect USB to SCSI adapter
  USB: storage: Add quirk for Adaptec USBConnect 2000 USB-to-SCSI Adapter
  USB: EHCI: unlink QHs even after the controller has stopped
  [SCSI] fix for bidi use after free
  [SCSI] fix regression that accidentally disabled block-based tcq
  [SCSI] libiscsi: fix potential buffer overrun in __iscsi_conn_send_pdu
  drm/radeon: Fix typo 'addr' -> 'entry' in rs400_gart_set_page
  drm/nouveau/runpm: fix module unload
  drm/radeon/px: fix module unload
  vgaswitcheroo: add vga_switcheroo_fini_domain_pm_ops
  drm/radeon: don't reset dma on r6xx-evergreen init
  drm/radeon: don't reset sdma on CIK init
  drm/radeon: don't reset dma on NI/SI init
  drm/radeon/dpm: fix resume on mullins
  drm/radeon: Disable HDP flush before every CS again for < r600
  ...

1 files changed, 85 insertions, 5 deletions

diff --git a/fs/aio.c b/fs/aio.c
index ae635872affb..733750096b71 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -141,6 +141,7 @@ struct kioctx {
 
 	struct {
 		unsigned	tail;
+		unsigned	completed_events;
 		spinlock_t	completion_lock;
 	} ____cacheline_aligned_in_smp;
 
@@ -792,6 +793,8 @@ void exit_aio(struct mm_struct *mm)
 
 	for (i = 0; i < table->nr; ++i) {
 		struct kioctx *ctx = table->table[i];
+		struct completion requests_done =
+			COMPLETION_INITIALIZER_ONSTACK(requests_done);
 
 		if (!ctx)
 			continue;
@@ -803,7 +806,10 @@ void exit_aio(struct mm_struct *mm)
 		 * that it needs to unmap the area, just set it to 0.
 		 */
 		ctx->mmap_size = 0;
-		kill_ioctx(mm, ctx, NULL);
+		kill_ioctx(mm, ctx, &requests_done);
+
+		/* Wait until all IO for the context are done. */
+		wait_for_completion(&requests_done);
 	}
 
 	RCU_INIT_POINTER(mm->ioctx_table, NULL);
@@ -857,6 +863,68 @@ out:
 	return ret;
 }
 
+/* refill_reqs_available
+ *	Updates the reqs_available reference counts used for tracking the
+ *	number of free slots in the completion ring.  This can be called
+ *	from aio_complete() (to optimistically update reqs_available) or
+ *	from aio_get_req() (the we're out of events case).  It must be
+ *	called holding ctx->completion_lock.
+ */
+static void refill_reqs_available(struct kioctx *ctx, unsigned head,
+                                  unsigned tail)
+{
+	unsigned events_in_ring, completed;
+
+	/* Clamp head since userland can write to it. */
+	head %= ctx->nr_events;
+	if (head <= tail)
+		events_in_ring = tail - head;
+	else
+		events_in_ring = ctx->nr_events - (head - tail);
+
+	completed = ctx->completed_events;
+	if (events_in_ring < completed)
+		completed -= events_in_ring;
+	else
+		completed = 0;
+
+	if (!completed)
+		return;
+
+	ctx->completed_events -= completed;
+	put_reqs_available(ctx, completed);
+}
+
+/* user_refill_reqs_available
+ *	Called to refill reqs_available when aio_get_req() encounters an
+ *	out of space in the completion ring.
+ */
+static void user_refill_reqs_available(struct kioctx *ctx)
+{
+	spin_lock_irq(&ctx->completion_lock);
+	if (ctx->completed_events) {
+		struct aio_ring *ring;
+		unsigned head;
+
+		/* Access of ring->head may race with aio_read_events_ring()
+		 * here, but that's okay since whether we read the old version
+		 * or the new version, and either will be valid.  The important
+		 * part is that head cannot pass tail since we prevent
+		 * aio_complete() from updating tail by holding
+		 * ctx->completion_lock.  Even if head is invalid, the check
+		 * against ctx->completed_events below will make sure we do the
+		 * safe/right thing.
+		 */
+		ring = kmap_atomic(ctx->ring_pages[0]);
+		head = ring->head;
+		kunmap_atomic(ring);
+
+		refill_reqs_available(ctx, head, ctx->tail);
+	}
+
+	spin_unlock_irq(&ctx->completion_lock);
+}
+
 /* aio_get_req
  *	Allocate a slot for an aio request.
  * Returns NULL if no requests are free.
@@ -865,8 +933,11 @@ static inline struct kiocb *aio_get_req(struct kioctx *ctx)
 {
 	struct kiocb *req;
 
-	if (!get_reqs_available(ctx))
-		return NULL;
+	if (!get_reqs_available(ctx)) {
+		user_refill_reqs_available(ctx);
+		if (!get_reqs_available(ctx))
+			return NULL;
+	}
 
 	req = kmem_cache_alloc(kiocb_cachep, GFP_KERNEL|__GFP_ZERO);
 	if (unlikely(!req))
@@ -925,8 +996,8 @@ void aio_complete(struct kiocb *iocb, long res, long res2)
 	struct kioctx	*ctx = iocb->ki_ctx;
 	struct aio_ring	*ring;
 	struct io_event	*ev_page, *event;
+	unsigned tail, pos, head;
 	unsigned long	flags;
-	unsigned tail, pos;
 
 	/*
 	 * Special case handling for sync iocbs:
@@ -987,10 +1058,14 @@ void aio_complete(struct kiocb *iocb, long res, long res2)
 	ctx->tail = tail;
 
 	ring = kmap_atomic(ctx->ring_pages[0]);
+	head = ring->head;
 	ring->tail = tail;
 	kunmap_atomic(ring);
 	flush_dcache_page(ctx->ring_pages[0]);
 
+	ctx->completed_events++;
+	if (ctx->completed_events > 1)
+		refill_reqs_available(ctx, head, tail);
 	spin_unlock_irqrestore(&ctx->completion_lock, flags);
 
 	pr_debug("added to ring %p at [%u]\n", iocb, tail);
@@ -1005,7 +1080,6 @@ void aio_complete(struct kiocb *iocb, long res, long res2)
 
 	/* everything turned out well, dispose of the aiocb. */
 	kiocb_free(iocb);
-	put_reqs_available(ctx, 1);
 
 	/*
 	 * We have to order our ring_info tail store above and test
@@ -1042,6 +1116,12 @@ static long aio_read_events_ring(struct kioctx *ctx,
 	tail = ring->tail;
 	kunmap_atomic(ring);
 
+	/*
+	 * Ensure that once we've read the current tail pointer, that
+	 * we also see the events that were stored up to the tail.
+	 */
+	smp_rmb();
+
 	pr_debug("h%u t%u m%u\n", head, tail, ctx->nr_events);
 
 	if (head == tail)