Public bug reported:

[Impact]
The way the driver deals with locking the DQ causes performance to suffer.

[Test Case]
Run iozone3 and validate performance is >= previous.

[Fix]
Once a DQ slot is allocated, it must be used. So, currently the driver locks 
the DQ while it builds and sends each task to the hardware, just in case there 
is a failure, so that it can reuse that slot. However - there is a point at 
which we the build/send is guaranteed to succeed, so we can release the lock at 
that point allowing new slots to be allocated.

[Regression Risk]
All fixes are localized to the hisi_sas drivers, which are drivers for the 
controllers in the hip06/hip07 SoCs, where we have directly tested these 
updates.

** Affects: linux (Ubuntu)
     Importance: Undecided
         Status: Incomplete

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https://bugs.launchpad.net/bugs/1774472

Title:
  hisi_sas: improve performance by optimizing DQ locking

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