Commit 84e5acb7 authored by Matthew Wilcox's avatar Matthew Wilcox
Browse files

XArray: Add xa_store_bh() and xa_store_irq() 



These convenience wrappers disable interrupts while taking the spinlock.
A number of drivers would otherwise have to open-code these functions.

Signed-off-by: default avatarMatthew Wilcox <willy@infradead.org>
parent 9c16bb88

Documentation/core-api/xarray.rst

+4 −1
Original line number Diff line number Diff line
@@ -167,6 +167,8 @@ Takes RCU read lock: 


Takes xa_lock internally:

 * :c:func:`xa_store`

 * :c:func:`xa_store_bh`

 * :c:func:`xa_store_irq`

 * :c:func:`xa_insert`

 * :c:func:`xa_erase`

 * :c:func:`xa_erase_bh`
@@ -247,7 +249,8 @@ Sharing the XArray with interrupt context is also possible, either 
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_erase_bh` and :c:func:`xa_erase_irq`.

functions such as :c:func:`xa_store_bh`, :c:func:`xa_store_irq`,

:c:func:`xa_erase_bh` and :c:func:`xa_erase_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

+52 −0
Original line number Diff line number Diff line
@@ -426,6 +426,58 @@ static inline int __xa_insert(struct xarray *xa, unsigned long index, 
	return -EEXIST;

}



/**

 * xa_store_bh() - Store this entry in the XArray.

 * @xa: XArray.

 * @index: Index into array.

 * @entry: New entry.

 * @gfp: Memory allocation flags.

 *

 * This function is like calling xa_store() except it disables softirqs

 * while holding the array lock.

 *

 * Context: Any context.  Takes and releases the xa_lock while

 * disabling softirqs.

 * Return: The entry which used to be at this index.

 */

static inline void *xa_store_bh(struct xarray *xa, unsigned long index,

		void *entry, gfp_t gfp)

{

	void *curr;



	xa_lock_bh(xa);

	curr = __xa_store(xa, index, entry, gfp);

	xa_unlock_bh(xa);



	return curr;

}



/**

 * xa_store_irq() - Erase this entry from the XArray.

 * @xa: XArray.

 * @index: Index into array.

 * @entry: New entry.

 * @gfp: Memory allocation flags.

 *

 * This function is like calling xa_store() except it disables interrupts

 * while holding the array lock.

 *

 * Context: Process context.  Takes and releases the xa_lock while

 * disabling interrupts.

 * Return: The entry which used to be at this index.

 */

static inline void *xa_store_irq(struct xarray *xa, unsigned long index,

		void *entry, gfp_t gfp)

{

	void *curr;



	xa_lock_irq(xa);

	curr = __xa_store(xa, index, entry, gfp);

	xa_unlock_irq(xa);



	return curr;

}



/**

 * xa_erase_bh() - Erase this entry from the XArray.

 * @xa: XArray.