From 45b1a97cb6e49d099ab9064d2a5102a5e0ec4b08 Mon Sep 17 00:00:00 2001 From: Juergen Gross Date: Fri, 17 Jan 2020 15:39:55 +0100 Subject: [PATCH] xen/blkfront: limit allocated memory size to actual use case MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit Today the Xen blkfront driver allocates memory for one struct blkfront_ring_info for each communication ring. This structure is statically sized for the maximum supported configuration resulting in a size of more than 90 kB. As the main size contributor is one array inside the struct, the memory allocation can easily be limited by moving this array to be the last structure element and to allocate only the memory for the actually needed array size. Acked-by: Roger Pau Monné Signed-off-by: Juergen Gross Signed-off-by: Jens Axboe --- drivers/block/xen-blkfront.c | 8 +++----- 1 file changed, 3 insertions(+), 5 deletions(-) diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c index c02be06c52995..61491167da199 100644 --- a/drivers/block/xen-blkfront.c +++ b/drivers/block/xen-blkfront.c @@ -151,9 +151,6 @@ MODULE_PARM_DESC(max_ring_page_order, "Maximum order of pages to be used for the #define BLK_RING_SIZE(info) \ __CONST_RING_SIZE(blkif, XEN_PAGE_SIZE * (info)->nr_ring_pages) -#define BLK_MAX_RING_SIZE \ - __CONST_RING_SIZE(blkif, XEN_PAGE_SIZE * XENBUS_MAX_RING_GRANTS) - /* * ring-ref%u i=(-1UL) would take 11 characters + 'ring-ref' is 8, so 19 * characters are enough. Define to 20 to keep consistent with backend. @@ -177,12 +174,12 @@ struct blkfront_ring_info { unsigned int evtchn, irq; struct work_struct work; struct gnttab_free_callback callback; - struct blk_shadow shadow[BLK_MAX_RING_SIZE]; struct list_head indirect_pages; struct list_head grants; unsigned int persistent_gnts_c; unsigned long shadow_free; struct blkfront_info *dev_info; + struct blk_shadow shadow[]; }; /* @@ -1915,7 +1912,8 @@ static int negotiate_mq(struct blkfront_info *info) info->nr_rings = 1; info->rinfo = kvcalloc(info->nr_rings, - sizeof(struct blkfront_ring_info), + struct_size(info->rinfo, shadow, + BLK_RING_SIZE(info)), GFP_KERNEL); if (!info->rinfo) { xenbus_dev_fatal(info->xbdev, -ENOMEM, "allocating ring_info structure"); -- 2.39.5