Merge tag 'v4.12-rc6' into patchwork

Linux 4.12-rc6

* tag 'v4.12-rc6': (813 commits)
  Linux 4.12-rc6
  mm: larger stack guard gap, between vmas
  virtio_balloon: disable VIOMMU support
  mm: correct the comment when reclaimed pages exceed the scanned pages
  userfaultfd: shmem: handle coredumping in handle_userfault()
  mm: numa: avoid waiting on freed migrated pages
  swap: cond_resched in swap_cgroup_prepare()
  mm/memory-failure.c: use compound_head() flags for huge pages
  perf unwind: Report module before querying isactivation in dwfl unwind
  fs: pass on flags in compat_writev
  objtool: Add fortify_panic as __noreturn function
  powerpc/debug: Add missing warn flag to WARN_ON's non-builtin path
  USB: gadgetfs, dummy-hcd, net2280: fix locking for callbacks
  drm: mxsfb_crtc: Reset the eLCDIF controller
  drm/mgag200: Fix to always set HiPri for G200e4 V2
  i2c: ismt: fix wrong device address when unmap the data buffer
  i2c: rcar: use correct length when unmapping DMA
  powerpc/xive: Fix offset for store EOI MMIOs
  drm/tegra: Correct idr_alloc() minimum id
  drm/tegra: Fix lockup on a use of staging API
  ...

Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>

1 files changed, 20 insertions, 0 deletions

diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index ed2573e149fa..710a005c6b7a 100644
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -344,6 +344,26 @@ static inline bool css_tryget_online(struct cgroup_subsys_state *css)
 }
 
 /**
+ * css_is_dying - test whether the specified css is dying
+ * @css: target css
+ *
+ * Test whether @css is in the process of offlining or already offline.  In
+ * most cases, ->css_online() and ->css_offline() callbacks should be
+ * enough; however, the actual offline operations are RCU delayed and this
+ * test returns %true also when @css is scheduled to be offlined.
+ *
+ * This is useful, for example, when the use case requires synchronous
+ * behavior with respect to cgroup removal.  cgroup removal schedules css
+ * offlining but the css can seem alive while the operation is being
+ * delayed.  If the delay affects user visible semantics, this test can be
+ * used to resolve the situation.
+ */
+static inline bool css_is_dying(struct cgroup_subsys_state *css)
+{
+	return !(css->flags & CSS_NO_REF) && percpu_ref_is_dying(&css->refcnt);
+}
+
+/**
  * css_put - put a css reference
  * @css: target css
  *