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author | Mitchel Humpherys <mitchelh@codeaurora.org> | 2014-02-17 21:58:39 (GMT) |
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committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2014-02-18 19:05:08 (GMT) |
commit | 53a91c68fa7b5f3ca45d2f1c88bf36a988b74e81 (patch) | |
tree | 09ecd833ab1fd77bbdf0b0e0ac4cd8655a396ec9 /drivers/staging/android/ion/ion_priv.h | |
parent | b9daf0b60b8a6a5151fca0e8cbb2dab763a3e92a (diff) | |
download | linux-53a91c68fa7b5f3ca45d2f1c88bf36a988b74e81.tar.xz |
staging: ion: Add private buffer flag to skip page pooling on free
Currently, when we free a buffer it might actually just go back into a
heap-specific page pool rather than going back to the system. This poses
a problem because sometimes (like when we're running a shrinker in low
memory conditions) we need to force the memory associated with the
buffer to truly be relinquished to the system rather than just going
back into a page pool.
There isn't a use case for this flag by Ion clients, so make it a
private flag. The main use case right now is to provide a mechanism for
the deferred free code to force stale buffers to bypass page pooling.
Cc: Colin Cross <ccross@android.com>
Cc: Android Kernel Team <kernel-team@android.com>
Signed-off-by: Mitchel Humpherys <mitchelh@codeaurora.org>
[jstultz: Minor commit subject tweak]
Signed-off-by: John Stultz <john.stultz@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/staging/android/ion/ion_priv.h')
-rw-r--r-- | drivers/staging/android/ion/ion_priv.h | 42 |
1 files changed, 41 insertions, 1 deletions
diff --git a/drivers/staging/android/ion/ion_priv.h b/drivers/staging/android/ion/ion_priv.h index bcf9d19..1eba3f2 100644 --- a/drivers/staging/android/ion/ion_priv.h +++ b/drivers/staging/android/ion/ion_priv.h @@ -38,6 +38,7 @@ struct ion_buffer *ion_handle_buffer(struct ion_handle *handle); * @dev: back pointer to the ion_device * @heap: back pointer to the heap the buffer came from * @flags: buffer specific flags + * @private_flags: internal buffer specific flags * @size: size of the buffer * @priv_virt: private data to the buffer representable as * a void * @@ -66,6 +67,7 @@ struct ion_buffer { struct ion_device *dev; struct ion_heap *heap; unsigned long flags; + unsigned long private_flags; size_t size; union { void *priv_virt; @@ -98,7 +100,11 @@ void ion_buffer_destroy(struct ion_buffer *buffer); * @map_user map memory to userspace * * allocate, phys, and map_user return 0 on success, -errno on error. - * map_dma and map_kernel return pointer on success, ERR_PTR on error. + * map_dma and map_kernel return pointer on success, ERR_PTR on + * error. @free will be called with ION_PRIV_FLAG_SHRINKER_FREE set in + * the buffer's private_flags when called from a shrinker. In that + * case, the pages being free'd must be truly free'd back to the + * system, not put in a page pool or otherwise cached. */ struct ion_heap_ops { int (*allocate)(struct ion_heap *heap, @@ -123,6 +129,17 @@ struct ion_heap_ops { #define ION_HEAP_FLAG_DEFER_FREE (1 << 0) /** + * private flags - flags internal to ion + */ +/* + * Buffer is being freed from a shrinker function. Skip any possible + * heap-specific caching mechanism (e.g. page pools). Guarantees that + * any buffer storage that came from the system allocator will be + * returned to the system allocator. + */ +#define ION_PRIV_FLAG_SHRINKER_FREE (1 << 0) + +/** * struct ion_heap - represents a heap in the system * @node: rb node to put the heap on the device's tree of heaps * @dev: back pointer to the ion_device @@ -258,6 +275,29 @@ void ion_heap_freelist_add(struct ion_heap *heap, struct ion_buffer *buffer); size_t ion_heap_freelist_drain(struct ion_heap *heap, size_t size); /** + * ion_heap_freelist_shrink - drain the deferred free + * list, skipping any heap-specific + * pooling or caching mechanisms + * + * @heap: the heap + * @size: amount of memory to drain in bytes + * + * Drains the indicated amount of memory from the deferred freelist immediately. + * Returns the total amount freed. The total freed may be higher depending + * on the size of the items in the list, or lower if there is insufficient + * total memory on the freelist. + * + * Unlike with @ion_heap_freelist_drain, don't put any pages back into + * page pools or otherwise cache the pages. Everything must be + * genuinely free'd back to the system. If you're free'ing from a + * shrinker you probably want to use this. Note that this relies on + * the heap.ops.free callback honoring the ION_PRIV_FLAG_SHRINKER_FREE + * flag. + */ +size_t ion_heap_freelist_shrink(struct ion_heap *heap, + size_t size); + +/** * ion_heap_freelist_size - returns the size of the freelist in bytes * @heap: the heap */ |