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authorMatthew Wilcox <willy@infradead.org>2018-11-26 16:08:43 -0500
committerMatthew Wilcox <willy@infradead.org>2018-12-06 08:26:17 -0500
commit55f3f7eab75c10d9b33d122670b5935ab64db50f (patch)
tree6a601ac3c08993730dfade808fe6806e1bfbf98c
parenteff3860bbfedbac6edac57fb0d7f3a60e860c1c3 (diff)
XArray: Add xa_cmpxchg_irq and xa_cmpxchg_bh
These convenience wrappers match the other _irq and _bh wrappers we already have. It turns out I'd already open-coded xa_cmpxchg_irq() in the shmem code, so convert that. Signed-off-by: Matthew Wilcox <willy@infradead.org>
-rw-r--r--Documentation/core-api/xarray.rst5
-rw-r--r--include/linux/xarray.h54
-rw-r--r--mm/shmem.c4
3 files changed, 59 insertions, 4 deletions
diff --git a/Documentation/core-api/xarray.rst b/Documentation/core-api/xarray.rst
index dbe96cb5558e..6a6d67acaf69 100644
--- a/Documentation/core-api/xarray.rst
+++ b/Documentation/core-api/xarray.rst
@@ -187,6 +187,8 @@ Takes xa_lock internally:
* :c:func:`xa_erase_bh`
* :c:func:`xa_erase_irq`
* :c:func:`xa_cmpxchg`
+ * :c:func:`xa_cmpxchg_bh`
+ * :c:func:`xa_cmpxchg_irq`
* :c:func:`xa_store_range`
* :c:func:`xa_alloc`
* :c:func:`xa_alloc_bh`
@@ -263,7 +265,8 @@ using :c:func:`xa_lock_irqsave` in both the interrupt handler and process
context, or :c:func:`xa_lock_irq` in process context and :c:func:`xa_lock`
in the interrupt handler. Some of the more common patterns have helper
functions such as :c:func:`xa_store_bh`, :c:func:`xa_store_irq`,
-:c:func:`xa_erase_bh` and :c:func:`xa_erase_irq`.
+:c:func:`xa_erase_bh`, :c:func:`xa_erase_irq`, :c:func:`xa_cmpxchg_bh`
+and :c:func:`xa_cmpxchg_irq`.
Sometimes you need to protect access to the XArray with a mutex because
that lock sits above another mutex in the locking hierarchy. That does
diff --git a/include/linux/xarray.h b/include/linux/xarray.h
index 564892e19f8c..f492e21c4aa2 100644
--- a/include/linux/xarray.h
+++ b/include/linux/xarray.h
@@ -554,6 +554,60 @@ static inline void *xa_cmpxchg(struct xarray *xa, unsigned long index,
}
/**
+ * xa_cmpxchg_bh() - Conditionally replace an entry in the XArray.
+ * @xa: XArray.
+ * @index: Index into array.
+ * @old: Old value to test against.
+ * @entry: New value to place in array.
+ * @gfp: Memory allocation flags.
+ *
+ * This function is like calling xa_cmpxchg() except it disables softirqs
+ * while holding the array lock.
+ *
+ * Context: Any context. Takes and releases the xa_lock while
+ * disabling softirqs. May sleep if the @gfp flags permit.
+ * Return: The old value at this index or xa_err() if an error happened.
+ */
+static inline void *xa_cmpxchg_bh(struct xarray *xa, unsigned long index,
+ void *old, void *entry, gfp_t gfp)
+{
+ void *curr;
+
+ xa_lock_bh(xa);
+ curr = __xa_cmpxchg(xa, index, old, entry, gfp);
+ xa_unlock_bh(xa);
+
+ return curr;
+}
+
+/**
+ * xa_cmpxchg_irq() - Conditionally replace an entry in the XArray.
+ * @xa: XArray.
+ * @index: Index into array.
+ * @old: Old value to test against.
+ * @entry: New value to place in array.
+ * @gfp: Memory allocation flags.
+ *
+ * This function is like calling xa_cmpxchg() except it disables interrupts
+ * while holding the array lock.
+ *
+ * Context: Process context. Takes and releases the xa_lock while
+ * disabling interrupts. May sleep if the @gfp flags permit.
+ * Return: The old value at this index or xa_err() if an error happened.
+ */
+static inline void *xa_cmpxchg_irq(struct xarray *xa, unsigned long index,
+ void *old, void *entry, gfp_t gfp)
+{
+ void *curr;
+
+ xa_lock_irq(xa);
+ curr = __xa_cmpxchg(xa, index, old, entry, gfp);
+ xa_unlock_irq(xa);
+
+ return curr;
+}
+
+/**
* xa_insert() - Store this entry in the XArray unless another entry is
* already present.
* @xa: XArray.
diff --git a/mm/shmem.c b/mm/shmem.c
index cddc72ac44d8..6adbdd349875 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -661,9 +661,7 @@ static int shmem_free_swap(struct address_space *mapping,
{
void *old;
- xa_lock_irq(&mapping->i_pages);
- old = __xa_cmpxchg(&mapping->i_pages, index, radswap, NULL, 0);
- xa_unlock_irq(&mapping->i_pages);
+ old = xa_cmpxchg_irq(&mapping->i_pages, index, radswap, NULL, 0);
if (old != radswap)
return -ENOENT;
free_swap_and_cache(radix_to_swp_entry(radswap));