Re: [PATCH 1/2] scsi: core: cleanup scsi_dev_queue_ready()

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On 2023/9/24 14:27, Wenchao Hao wrote:
On 2023/9/22 20:50, Damien Le Moal wrote:
On 2023/09/22 2:38, Wenchao Hao wrote:
This is just a cleanup for scsi_dev_queue_ready() to avoid
redundant goto and if statement, it did not change the origin
logic.

Signed-off-by: Wenchao Hao <haowenchao2@xxxxxxxxxx>
---
  drivers/scsi/scsi_lib.c | 35 ++++++++++++++++++-----------------
  1 file changed, 18 insertions(+), 17 deletions(-)

diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index ca5eb058d5c7..f3e388127dbd 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -1254,28 +1254,29 @@ static inline int scsi_dev_queue_ready(struct request_queue *q,
      int token;
      token = sbitmap_get(&sdev->budget_map);
-    if (atomic_read(&sdev->device_blocked)) {
-        if (token < 0)
-            goto out;
+    if (token < 0)
+        return -1;

This is changing how this function works...


I don't think so...
The origin function flow:

static inline int scsi_dev_queue_ready(struct request_queue *q,
                   struct scsi_device *sdev)
{
     ...
     token = sbitmap_get(&sdev->budget_map);
     if (atomic_read(&sdev->device_blocked)) {
         if (token < 0)
             goto out;
     }
     return token;
out:
     return -1
}

If the token is less than 0, it would always return -1. So we can found
it's not necessary to check token after atomic_read().

-        if (scsi_device_busy(sdev) > 1)
-            goto out_dec;
+    /*
+     * device_blocked is not set at mostly time, so check it first
+     * and return token when it is not set.
+     */
+    if (!atomic_read(&sdev->device_blocked))
+        return token;

...because you reversed the tests order.

As explained in comment, the device_blocked is not set at mostly time,
so when it's not set, just return the token.


Friendly ping...




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