linux-kernel - [PATCH v3] staging: ion: Fix ion_cma

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Date:   Fri, 15 Dec 2017 19:59:47 -0800
From:   John Stultz <john.stultz@...aro.org>
To:     lkml <linux-kernel@...r.kernel.org>
Cc:     John Stultz <john.stultz@...aro.org>,
        Laura Abbott <labbott@...hat.com>,
        Sumit Semwal <sumit.semwal@...aro.org>,
        Benjamin Gaignard <benjamin.gaignard@...aro.org>,
        Archit Taneja <architt@...eaurora.org>,
        Greg KH <gregkh@...uxfoundation.org>,
        Daniel Vetter <daniel@...ll.ch>,
        Dmitry Shmidt <dimitrysh@...gle.com>,
        Todd Kjos <tkjos@...gle.com>,
        Amit Pundir <amit.pundir@...aro.org>
Subject: [PATCH v3] staging: ion: Fix ion_cma_heap allocations

In trying to add support for drm_hwcomposer to HiKey,
I've needed to utilize the ION CMA heap, and I've noticed
problems with allocations on newer kernels failing.

It seems back with 204f672255c2 ("ion: Use CMA APIs directly"),
the ion_cma_heap code was modified to use the CMA API, but
kept the arguments as buffer lengths rather then number of pages.

This results in errors as we don't have enough pages in CMA to
satisfy the exaggerated requests.

This patch converts the ion_cma_heap CMA API usage to properly
request pages.

It also fixes a minor issue in the allocation where in the error
path, the cma_release is called with the buffer->size value which
hasn't yet been set.

Cc: Laura Abbott <labbott@...hat.com>
Cc: Sumit Semwal <sumit.semwal@...aro.org>
Cc: Benjamin Gaignard <benjamin.gaignard@...aro.org>
Cc: Archit Taneja <architt@...eaurora.org>
Cc: Greg KH <gregkh@...uxfoundation.org>
Cc: Daniel Vetter <daniel@...ll.ch>
Cc: Dmitry Shmidt <dimitrysh@...gle.com>
Cc: Todd Kjos <tkjos@...gle.com>
Cc: Amit Pundir <amit.pundir@...aro.org>
Fixes: 204f672255c2 ("staging: android: ion: Use CMA APIs directly")
Acked-by: Laura Abbott <labbott@...hat.com>
Signed-off-by: John Stultz <john.stultz@...aro.org>
---
v2: Fix build errors when CONFIG_CMA_ALIGNMENT isn't defined
v3: Make CMA heap depend on DMA_CMA instead of just CMA to address
    the undefined CONFIG_CMA_ALIGNMENT issue.

 drivers/staging/android/ion/Kconfig        |  2 +-
 drivers/staging/android/ion/ion_cma_heap.c | 15 +++++++++++----
 2 files changed, 12 insertions(+), 5 deletions(-)

diff --git a/drivers/staging/android/ion/Kconfig b/drivers/staging/android/ion/Kconfig
index a517b2d..8f64941 100644
--- a/drivers/staging/android/ion/Kconfig
+++ b/drivers/staging/android/ion/Kconfig
@@ -37,7 +37,7 @@ config ION_CHUNK_HEAP
 
 config ION_CMA_HEAP
 	bool "Ion CMA heap support"
-	depends on ION && CMA
+	depends on ION && DMA_CMA
 	help
 	  Choose this option to enable CMA heaps with Ion. This heap is backed
 	  by the Contiguous Memory Allocator (CMA). If your system has these
diff --git a/drivers/staging/android/ion/ion_cma_heap.c b/drivers/staging/android/ion/ion_cma_heap.c
index dd5545d..86196ff 100644
--- a/drivers/staging/android/ion/ion_cma_heap.c
+++ b/drivers/staging/android/ion/ion_cma_heap.c
@@ -39,9 +39,15 @@ static int ion_cma_allocate(struct ion_heap *heap, struct ion_buffer *buffer,
 	struct ion_cma_heap *cma_heap = to_cma_heap(heap);
 	struct sg_table *table;
 	struct page *pages;
+	unsigned long size = PAGE_ALIGN(len);
+	unsigned long nr_pages = size >> PAGE_SHIFT;
+	unsigned long align = get_order(size);
 	int ret;
 
-	pages = cma_alloc(cma_heap->cma, len, 0, GFP_KERNEL);
+	if (align > CONFIG_CMA_ALIGNMENT)
+		align = CONFIG_CMA_ALIGNMENT;
+
+	pages = cma_alloc(cma_heap->cma, nr_pages, align, GFP_KERNEL);
 	if (!pages)
 		return -ENOMEM;
 
@@ -53,7 +59,7 @@ static int ion_cma_allocate(struct ion_heap *heap, struct ion_buffer *buffer,
 	if (ret)
 		goto free_mem;
 
-	sg_set_page(table->sgl, pages, len, 0);
+	sg_set_page(table->sgl, pages, size, 0);
 
 	buffer->priv_virt = pages;
 	buffer->sg_table = table;
@@ -62,7 +68,7 @@ static int ion_cma_allocate(struct ion_heap *heap, struct ion_buffer *buffer,
 free_mem:
 	kfree(table);
 err:
-	cma_release(cma_heap->cma, pages, buffer->size);
+	cma_release(cma_heap->cma, pages, nr_pages);
 	return -ENOMEM;
 }
 
@@ -70,9 +76,10 @@ static void ion_cma_free(struct ion_buffer *buffer)
 {
 	struct ion_cma_heap *cma_heap = to_cma_heap(buffer->heap);
 	struct page *pages = buffer->priv_virt;
+	unsigned long nr_pages = PAGE_ALIGN(buffer->size) >> PAGE_SHIFT;
 
 	/* release memory */
-	cma_release(cma_heap->cma, pages, buffer->size);
+	cma_release(cma_heap->cma, pages, nr_pages);
 	/* release sg table */
 	sg_free_table(buffer->sg_table);
 	kfree(buffer->sg_table);
-- 
2.7.4