From: Roger Pau Monne Date: Mon, 18 Mar 2013 16:49:35 +0000 (+0100) Subject: xen-blkfront: pre-allocate pages for requests X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=9c1e050caeb4d1250f8ceef1180a8b3d0db6c624;p=GitHub%2Fexynos8895%2Fandroid_kernel_samsung_universal8895.git xen-blkfront: pre-allocate pages for requests This prevents us from having to call alloc_page while we are preparing the request. Since blkfront was calling alloc_page with a spinlock held we used GFP_ATOMIC, which can fail if we are requesting a lot of pages since it is using the emergency memory pools. Allocating all the pages at init prevents us from having to call alloc_page, thus preventing possible failures. Signed-off-by: Roger Pau Monné Cc: Konrad Rzeszutek Wilk Cc: xen-devel@lists.xen.org Signed-off-by: Konrad Rzeszutek Wilk --- diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c index 97324cd18f4b..c64043323399 100644 --- a/drivers/block/xen-blkfront.c +++ b/drivers/block/xen-blkfront.c @@ -165,6 +165,69 @@ static int add_id_to_freelist(struct blkfront_info *info, return 0; } +static int fill_grant_buffer(struct blkfront_info *info, int num) +{ + struct page *granted_page; + struct grant *gnt_list_entry, *n; + int i = 0; + + while(i < num) { + gnt_list_entry = kzalloc(sizeof(struct grant), GFP_NOIO); + if (!gnt_list_entry) + goto out_of_memory; + + granted_page = alloc_page(GFP_NOIO); + if (!granted_page) { + kfree(gnt_list_entry); + goto out_of_memory; + } + + gnt_list_entry->pfn = page_to_pfn(granted_page); + gnt_list_entry->gref = GRANT_INVALID_REF; + list_add(&gnt_list_entry->node, &info->persistent_gnts); + i++; + } + + return 0; + +out_of_memory: + list_for_each_entry_safe(gnt_list_entry, n, + &info->persistent_gnts, node) { + list_del(&gnt_list_entry->node); + __free_page(pfn_to_page(gnt_list_entry->pfn)); + kfree(gnt_list_entry); + i--; + } + BUG_ON(i != 0); + return -ENOMEM; +} + +static struct grant *get_grant(grant_ref_t *gref_head, + struct blkfront_info *info) +{ + struct grant *gnt_list_entry; + unsigned long buffer_mfn; + + BUG_ON(list_empty(&info->persistent_gnts)); + gnt_list_entry = list_first_entry(&info->persistent_gnts, struct grant, + node); + list_del(&gnt_list_entry->node); + + if (gnt_list_entry->gref != GRANT_INVALID_REF) { + info->persistent_gnts_c--; + return gnt_list_entry; + } + + /* Assign a gref to this page */ + gnt_list_entry->gref = gnttab_claim_grant_reference(gref_head); + BUG_ON(gnt_list_entry->gref == -ENOSPC); + buffer_mfn = pfn_to_mfn(gnt_list_entry->pfn); + gnttab_grant_foreign_access_ref(gnt_list_entry->gref, + info->xbdev->otherend_id, + buffer_mfn, 0); + return gnt_list_entry; +} + static const char *op_name(int op) { static const char *const names[] = { @@ -306,7 +369,6 @@ static int blkif_queue_request(struct request *req) */ bool new_persistent_gnts; grant_ref_t gref_head; - struct page *granted_page; struct grant *gnt_list_entry = NULL; struct scatterlist *sg; @@ -370,42 +432,9 @@ static int blkif_queue_request(struct request *req) fsect = sg->offset >> 9; lsect = fsect + (sg->length >> 9) - 1; - if (info->persistent_gnts_c) { - BUG_ON(list_empty(&info->persistent_gnts)); - gnt_list_entry = list_first_entry( - &info->persistent_gnts, - struct grant, node); - list_del(&gnt_list_entry->node); - - ref = gnt_list_entry->gref; - buffer_mfn = pfn_to_mfn(gnt_list_entry->pfn); - info->persistent_gnts_c--; - } else { - ref = gnttab_claim_grant_reference(&gref_head); - BUG_ON(ref == -ENOSPC); - - gnt_list_entry = - kmalloc(sizeof(struct grant), - GFP_ATOMIC); - if (!gnt_list_entry) - return -ENOMEM; - - granted_page = alloc_page(GFP_ATOMIC); - if (!granted_page) { - kfree(gnt_list_entry); - return -ENOMEM; - } - - gnt_list_entry->pfn = - page_to_pfn(granted_page); - gnt_list_entry->gref = ref; - - buffer_mfn = pfn_to_mfn(page_to_pfn( - granted_page)); - gnttab_grant_foreign_access_ref(ref, - info->xbdev->otherend_id, - buffer_mfn, 0); - } + gnt_list_entry = get_grant(&gref_head, info); + ref = gnt_list_entry->gref; + buffer_mfn = pfn_to_mfn(gnt_list_entry->pfn); info->shadow[id].grants_used[i] = gnt_list_entry; @@ -803,17 +832,20 @@ static void blkif_free(struct blkfront_info *info, int suspend) blk_stop_queue(info->rq); /* Remove all persistent grants */ - if (info->persistent_gnts_c) { + if (!list_empty(&info->persistent_gnts)) { list_for_each_entry_safe(persistent_gnt, n, &info->persistent_gnts, node) { list_del(&persistent_gnt->node); - gnttab_end_foreign_access(persistent_gnt->gref, 0, 0UL); + if (persistent_gnt->gref != GRANT_INVALID_REF) { + gnttab_end_foreign_access(persistent_gnt->gref, + 0, 0UL); + info->persistent_gnts_c--; + } __free_page(pfn_to_page(persistent_gnt->pfn)); kfree(persistent_gnt); - info->persistent_gnts_c--; } - BUG_ON(info->persistent_gnts_c != 0); } + BUG_ON(info->persistent_gnts_c != 0); /* No more gnttab callback work. */ gnttab_cancel_free_callback(&info->callback); @@ -1008,6 +1040,12 @@ static int setup_blkring(struct xenbus_device *dev, sg_init_table(info->sg, BLKIF_MAX_SEGMENTS_PER_REQUEST); + /* Allocate memory for grants */ + err = fill_grant_buffer(info, BLK_RING_SIZE * + BLKIF_MAX_SEGMENTS_PER_REQUEST); + if (err) + goto fail; + err = xenbus_grant_ring(dev, virt_to_mfn(info->ring.sring)); if (err < 0) { free_page((unsigned long)sring);