+ dmapool-link-blocks-across-pages-fix.patch added to mm-unstable branch

[Andrew Morton <akpm@linux-foundation.org>]

The patch titled
     Subject: dmapool: push new blocks in ascending order
has been added to the -mm mm-unstable branch.  Its filename is
     dmapool-link-blocks-across-pages-fix.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/dmapool-link-blocks-across-pages-fix.patch

This patch will later appear in the mm-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------
From: Keith Busch <kbusch@kernel.org>
Subject: dmapool: push new blocks in ascending order
Date: Tue, 21 Feb 2023 08:54:00 -0800

Some users of the dmapool need their allocations to happen in ascending
order.  The recent optimizations pushed the blocks in reverse order, so
restore the previous behavior by linking the next available block from
low-to-high.

usb/chipidea/udc.c qh_pool called "ci_hw_qh".  My initial thought was
dmapool isn't the right API if you need a specific order when allocating
from it, but I can't readily test any changes to that driver.  Restoring
the previous behavior is easy enough.

Link: https://lkml.kernel.org/r/20230221165400.1595247-1-kbusch@meta.com
Fixes: ced6d06a81fb69 ("dmapool: link blocks across pages")
Signed-off-by: Keith Busch <kbusch@kernel.org>
Reported-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
Tested-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
Cc: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---


--- a/mm/dmapool.c~dmapool-link-blocks-across-pages-fix
+++ b/mm/dmapool.c
@@ -301,7 +301,7 @@ EXPORT_SYMBOL(dma_pool_create);
 static void pool_initialise_page(struct dma_pool *pool, struct dma_page *page)
 {
 	unsigned int next_boundary = pool->boundary, offset = 0;
-	struct dma_block *block;
+	struct dma_block *block, *first = NULL, *last = NULL;
 
 	pool_init_page(pool, page);
 	while (offset + pool->size <= pool->allocation) {
@@ -312,11 +312,22 @@ static void pool_initialise_page(struct dma_pool *pool, struct dma_page *page)
 		}
 
 		block = page->vaddr + offset;
-		pool_block_push(pool, block, page->dma + offset);
+		block->dma = page->dma + offset;
+		block->next_block = NULL;
+
+		if (last)
+			last->next_block = block;
+		else
+			first = block;
+		last = block;
+
 		offset += pool->size;
 		pool->nr_blocks++;
 	}
 
+	last->next_block = pool->next_block;
+	pool->next_block = first;
+
 	list_add(&page->page_list, &pool->page_list);
 	pool->nr_pages++;
 }
_

Patches currently in -mm which might be from kbusch@kernel.org are

dmapool-add-alloc-free-performance-test.patch
dmapool-move-debug-code-to-own-functions.patch
dmapool-rearrange-page-alloc-failure-handling.patch
dmapool-consolidate-page-initialization.patch
dmapool-simplify-freeing.patch
dmapool-dont-memset-on-free-twice.patch
dmapool-link-blocks-across-pages.patch
dmapool-link-blocks-across-pages-fix.patch
dmapool-create-destroy-cleanup.patch