null_blk: allow zero poll queues

There isn't any reason to not allow zero poll queues from user
viewpoint.

Also sometimes we need to compare io poll between poll mode and irq
mode, so not allowing poll queues is bad.

Fixes: 15dfc662ef31 ("null_blk: Fix handling of submit_queues and poll_queues attributes")
Cc: Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20211203023935.3424042-1-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/drivers/block/null_blk/main.c b/drivers/block/null_blk/main.c
index 54f7d490f8ebb6ebf55a85d1bdae6f038b276882..b4ff5ae1f70ce994696f8b631ec42a3e658f1444 100644 (file)
--- a/drivers/block/null_blk/main.c
+++ b/drivers/block/null_blk/main.c
@@ -340,9 +340,9 @@ static int nullb_update_nr_hw_queues(struct nullb_device *dev,
                return 0;
 
        /*
-        * Make sure at least one queue exists for each of submit and poll.
+        * Make sure at least one submit queue exists.
         */
-       if (!submit_queues || !poll_queues)
+       if (!submit_queues)
                return -EINVAL;
 
        /*
@@ -1917,8 +1917,6 @@ static int null_validate_conf(struct nullb_device *dev)
 
        if (dev->poll_queues > g_poll_queues)
                dev->poll_queues = g_poll_queues;
-       else if (dev->poll_queues == 0)
-               dev->poll_queues = 1;
        dev->prev_poll_queues = dev->poll_queues;
 
        dev->queue_mode = min_t(unsigned int, dev->queue_mode, NULL_Q_MQ);