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XArray: Add xa_store_bh() and xa_store_irq()

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

Signed-off-by: Matthew Wilcox <willy@infradead.org>
This commit is contained in:
Matthew Wilcox 2018-10-26 14:41:29 -04:00
parent 9c16bb8890
commit 84e5acb76d
2 changed files with 56 additions and 1 deletions
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5
Documentation/core-api/xarray.rst
View File

@ -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

52
include/linux/xarray.h
View File

@ -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.