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Date: Tue, 6 Jan 2015 21:19:03 +0800 From: Bob Liu <bob.liu@...cle.com> To: xen-devel@...ts.xen.org Cc: konrad.wilk@...cle.com, linux-kernel@...r.kernel.org, david.vrabel@...rix.com, roger.pau@...rix.com, junxiao.bi@...cle.com, Bob Liu <bob.liu@...cle.com> Subject: [PATCH] xen/blkfront: restart request queue when there is enough persistent_gnts_c When there is no enough free grants, gnttab_alloc_grant_references() will fail and block request queue will stop. If the system is always lack of grants, blkif_restart_queue_callback() can't be scheduled and block request queue can't be restart(block I/O hang). But when there are former requests complete, some grants may free to persistent_gnts_c, we can give the request queue another chance to restart and avoid block hang. Reported-by: Junxiao Bi <junxiao.bi@...cle.com> Signed-off-by: Bob Liu <bob.liu@...cle.com> --- drivers/block/xen-blkfront.c | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c index 2236c6f..dd30f99 100644 --- a/drivers/block/xen-blkfront.c +++ b/drivers/block/xen-blkfront.c @@ -1125,6 +1125,17 @@ static void blkif_completion(struct blk_shadow *s, struct blkfront_info *info, } } } + + /* + * Request queue would be stopped if failed to alloc enough grants and + * won't be restarted until gnttab_free_count >= info->callback->count. + * + * But there is another case, once we have enough persistent grants we + * can try to restart the request queue instead of continue to wait for + * 'gnttab_free_count'. + */ + if (info->persistent_gnts_c >= info->callback.count) + schedule_work(&info->work); } static irqreturn_t blkif_interrupt(int irq, void *dev_id) -- 1.7.10.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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