2022-12-16 20:20:23

by Keith Busch

Subject: [PATCHv2 08/11] dmapool: consolidate page initialization

From: Keith Busch <[email protected]>

Various fields of the dma pool are set in different places. Move it all
to one function.

Signed-off-by: Keith Busch <[email protected]>
---
mm/dmapool.c | 11 +++++------
1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/mm/dmapool.c b/mm/dmapool.c
index f77e2af4941de..33d20ceff18c5 100644
--- a/mm/dmapool.c
+++ b/mm/dmapool.c
@@ -202,6 +202,8 @@ static void pool_initialise_page(struct dma_pool *pool, struct dma_page *page)
unsigned int offset = 0;
unsigned int next_boundary = pool->boundary;

+ page->in_use = 0;
+ page->offset = 0;
do {
unsigned int next = offset + pool->size;
if (unlikely((next + pool->size) >= next_boundary)) {
@@ -211,6 +213,8 @@ static void pool_initialise_page(struct dma_pool *pool, struct dma_page *page)
*(int *)(page->vaddr + offset) = next;
offset = next;
} while (offset < pool->allocation);
+
+ list_add(&page->page_list, &pool->page_list);
}

static struct dma_page *pool_alloc_page(struct dma_pool *pool, gfp_t mem_flags)
@@ -229,10 +233,6 @@ static struct dma_page *pool_alloc_page(struct dma_pool *pool, gfp_t mem_flags)
#ifdef DMAPOOL_DEBUG
memset(page->vaddr, POOL_POISON_FREED, pool->allocation);
#endif
- pool_initialise_page(pool, page);
- page->in_use = 0;
- page->offset = 0;
-
return page;
}

@@ -354,8 +354,7 @@ void *dma_pool_alloc(struct dma_pool *pool, gfp_t mem_flags,
return NULL;

spin_lock_irqsave(&pool->lock, flags);
-
- list_add(&page->page_list, &pool->page_list);
+ pool_initialise_page(pool, page);
ready:
page->in_use++;
offset = page->offset;
--
2.30.2

2022-12-23 17:44:22

by Christoph Hellwig

Subject: Re: [PATCHv2 08/11] dmapool: consolidate page initialization

> + page->in_use = 0;
> + page->offset = 0;

This move makes total sense to me.

> return NULL;
>
> spin_lock_irqsave(&pool->lock, flags);
> -
> - list_add(&page->page_list, &pool->page_list);
> + pool_initialise_page(pool, page);

.. but this now moves all of pool_initialise_page inside the
pool->lock critical section. Is that really a good idea?