From 2c561246524c3319473bf47b558354f7ff47f0cf Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Tue, 3 Feb 2015 12:55:31 +0100 Subject: block: Simplify bsg complete all It took me a few tries to figure out what this code did; lets rewrite it into a more regular form. The thing that makes this one 'special' is the BSG_F_BLOCK flag, if that is not set we're not supposed/allowed to block and should spin wait for completion. The (new) io_wait_event() will never see a false condition in case of the spinning and we will therefore not block. Cc: Linus Torvalds Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Jens Axboe --- block/bsg.c | 72 +++++++++++++++++++++---------------------------------------- 1 file changed, 25 insertions(+), 47 deletions(-) (limited to 'block') diff --git a/block/bsg.c b/block/bsg.c index 276e869e686c..d214e929ce18 100644 --- a/block/bsg.c +++ b/block/bsg.c @@ -136,42 +136,6 @@ static inline struct hlist_head *bsg_dev_idx_hash(int index) return &bsg_device_list[index & (BSG_LIST_ARRAY_SIZE - 1)]; } -static int bsg_io_schedule(struct bsg_device *bd) -{ - DEFINE_WAIT(wait); - int ret = 0; - - spin_lock_irq(&bd->lock); - - BUG_ON(bd->done_cmds > bd->queued_cmds); - - /* - * -ENOSPC or -ENODATA? I'm going for -ENODATA, meaning "I have no - * work to do", even though we return -ENOSPC after this same test - * during bsg_write() -- there, it means our buffer can't have more - * bsg_commands added to it, thus has no space left. - */ - if (bd->done_cmds == bd->queued_cmds) { - ret = -ENODATA; - goto unlock; - } - - if (!test_bit(BSG_F_BLOCK, &bd->flags)) { - ret = -EAGAIN; - goto unlock; - } - - prepare_to_wait(&bd->wq_done, &wait, TASK_UNINTERRUPTIBLE); - spin_unlock_irq(&bd->lock); - io_schedule(); - finish_wait(&bd->wq_done, &wait); - - return ret; -unlock: - spin_unlock_irq(&bd->lock); - return ret; -} - static int blk_fill_sgv4_hdr_rq(struct request_queue *q, struct request *rq, struct sg_io_v4 *hdr, struct bsg_device *bd, fmode_t has_write_perm) @@ -482,6 +446,30 @@ static int blk_complete_sgv4_hdr_rq(struct request *rq, struct sg_io_v4 *hdr, return ret; } +static bool bsg_complete(struct bsg_device *bd) +{ + bool ret = false; + bool spin; + + do { + spin_lock_irq(&bd->lock); + + BUG_ON(bd->done_cmds > bd->queued_cmds); + + /* + * All commands consumed. + */ + if (bd->done_cmds == bd->queued_cmds) + ret = true; + + spin = !test_bit(BSG_F_BLOCK, &bd->flags); + + spin_unlock_irq(&bd->lock); + } while (!ret && spin); + + return ret; +} + static int bsg_complete_all_commands(struct bsg_device *bd) { struct bsg_command *bc; @@ -492,17 +480,7 @@ static int bsg_complete_all_commands(struct bsg_device *bd) /* * wait for all commands to complete */ - ret = 0; - do { - ret = bsg_io_schedule(bd); - /* - * look for -ENODATA specifically -- we'll sometimes get - * -ERESTARTSYS when we've taken a signal, but we can't - * return until we're done freeing the queue, so ignore - * it. The signal will get handled when we're done freeing - * the bsg_device. - */ - } while (ret != -ENODATA); + io_wait_event(bd->wq_done, bsg_complete(bd)); /* * discard done commands -- cgit v1.2.3