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| author | Dongli Zhang <dongli.zhang@oracle.com> | 2017-06-28 14:57:28 +0200 |
|---|---|---|
| committer | Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> | 2017-07-25 17:31:09 +0200 |
| commit | bd912ef3e46b6edb51bb8af4b73fd2be7817e305 (patch) | |
| tree | 61b5281d5730da8d913a400b63182e64375bdc02 /drivers/block/xen-blkfront.c | |
| parent | xen-blkfront: fix mq start/stop race (diff) | |
| download | linux-bd912ef3e46b6edb51bb8af4b73fd2be7817e305.tar.xz linux-bd912ef3e46b6edb51bb8af4b73fd2be7817e305.zip | |
xen/blkfront: always allocate grants first from per-queue persistent grants
This patch partially reverts 3df0e50 ("xen/blkfront: pseudo support for
multi hardware queues/rings"). The xen-blkfront queue/ring might hang due
to grants allocation failure in the situation when gnttab_free_head is
almost empty while many persistent grants are reserved for this queue/ring.
As persistent grants management was per-queue since 73716df ("xen/blkfront:
make persistent grants pool per-queue"), we should always allocate from
persistent grants first.
Acked-by: Roger Pau Monné <roger.pau@citrix.com>
Signed-off-by: Dongli Zhang <dongli.zhang@oracle.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Diffstat (limited to 'drivers/block/xen-blkfront.c')
| -rw-r--r-- | drivers/block/xen-blkfront.c | 19 |
1 files changed, 11 insertions, 8 deletions
diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c index 04eeb540490f..98e34e4c62b8 100644 --- a/drivers/block/xen-blkfront.c +++ b/drivers/block/xen-blkfront.c @@ -708,6 +708,7 @@ static int blkif_queue_rw_req(struct request *req, struct blkfront_ring_info *ri * existing persistent grants, or if we have to get new grants, * as there are not sufficiently many free. */ + bool new_persistent_gnts = false; struct scatterlist *sg; int num_sg, max_grefs, num_grant; @@ -719,19 +720,21 @@ static int blkif_queue_rw_req(struct request *req, struct blkfront_ring_info *ri */ max_grefs += INDIRECT_GREFS(max_grefs); - /* - * We have to reserve 'max_grefs' grants because persistent - * grants are shared by all rings. - */ - if (max_grefs > 0) - if (gnttab_alloc_grant_references(max_grefs, &setup.gref_head) < 0) { + /* Check if we have enough persistent grants to allocate a requests */ + if (rinfo->persistent_gnts_c < max_grefs) { + new_persistent_gnts = true; + + if (gnttab_alloc_grant_references( + max_grefs - rinfo->persistent_gnts_c, + &setup.gref_head) < 0) { gnttab_request_free_callback( &rinfo->callback, blkif_restart_queue_callback, rinfo, - max_grefs); + max_grefs - rinfo->persistent_gnts_c); return 1; } + } /* Fill out a communications ring structure. */ id = blkif_ring_get_request(rinfo, req, &ring_req); @@ -832,7 +835,7 @@ static int blkif_queue_rw_req(struct request *req, struct blkfront_ring_info *ri if (unlikely(require_extra_req)) rinfo->shadow[extra_id].req = *extra_ring_req; - if (max_grefs > 0) + if (new_persistent_gnts) gnttab_free_grant_references(setup.gref_head); return 0; |