XArray: Add xa_cmpxchg_irq and xa_cmpxchg_bh (55f3f7ea) · Commits · 戴 / test

Documentation/core-api/xarray.rst

+4 −1

Original line number	Diff line number	Diff line
		@@ -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

include/linux/xarray.h

+54 −0

Original line number	Diff line number	Diff line
		@@ -553,6 +553,60 @@ static inline void xa_cmpxchg(struct xarray xa, unsigned long index,
		return curr;
		}

		/**
		* 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.

mm/shmem.c

+1 −3

Original line number	Diff line number	Diff line
		@@ -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));

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