Merge branch 'fixes' into arm/soc

Merge in a few pending fixes from pre-5.1 that didn't get sent in:

MAINTAINERS: update arch/arm/mach-davinci
ARM: dts: ls1021: Fix SGMII PCS link remaining down after PHY disconnect
ARM: dts: imx6q-logicpd: Reduce inrush current on USBH1
ARM: dts: imx6q-logicpd: Reduce inrush current on start
ARM: dts: imx: Fix the AR803X phy-mode
ARM: dts: sun8i: a33: Reintroduce default pinctrl muxing
arm64: dts: allwinner: a64: Rename hpvcc-supply to cpvdd-supply
ARM: sunxi: fix a leaked reference by adding missing of_node_put
ARM: sunxi: fix a leaked reference by adding missing of_node_put

Signed-off-by: Olof Johansson <olof@lixom.net>

1 files changed, 21 insertions, 0 deletions

diff --git a/include/linux/sched/mm.h b/include/linux/sched/mm.h
index 0cd9f10423fb..a3fda9f024c3 100644
--- a/include/linux/sched/mm.h
+++ b/include/linux/sched/mm.h
@@ -49,6 +49,27 @@ static inline void mmdrop(struct mm_struct *mm)
 		__mmdrop(mm);
 }
 
+/*
+ * This has to be called after a get_task_mm()/mmget_not_zero()
+ * followed by taking the mmap_sem for writing before modifying the
+ * vmas or anything the coredump pretends not to change from under it.
+ *
+ * NOTE: find_extend_vma() called from GUP context is the only place
+ * that can modify the "mm" (notably the vm_start/end) under mmap_sem
+ * for reading and outside the context of the process, so it is also
+ * the only case that holds the mmap_sem for reading that must call
+ * this function. Generally if the mmap_sem is hold for reading
+ * there's no need of this check after get_task_mm()/mmget_not_zero().
+ *
+ * This function can be obsoleted and the check can be removed, after
+ * the coredump code will hold the mmap_sem for writing before
+ * invoking the ->core_dump methods.
+ */
+static inline bool mmget_still_valid(struct mm_struct *mm)
+{
+	return likely(!mm->core_state);
+}
+
 /**
  * mmget() - Pin the address space associated with a &struct mm_struct.
  * @mm: The address space to pin.