Re: [PATCH v4 04/54] scsi: BusLogic: Pass the host pointer directly to several functions

[Khalid Aziz <khalid@gonehiking.org>]

On Mon, Sep 28, 2026 at 12:28:57PM -0700, Bart Van Assche wrote:
> On 9/28/26 11:55 AM, Khalid Aziz wrote:
> > I prefer not to pull in macro definitions from header files into the
> > driver code. This opens up possibility for API inconsistencies if
> > the macro in header file is ever updated.
> The DEF_SCSI_QCMD() macro was introduced in 2010 and there have not
> been any changes to its functionality in the 16 years that passed since
> its introduction. Hence, I think it's unlikely that it will be changed
> in the future.
> 
> > Why not extract struct *scsi_host in blogic_qcmd_lck() from
> > struct *scsi_cmd instead and continue to use DEF_SCSI_QCMD()?
> 
> Because it is the only way to avoid __assume_ctx_lock() in
> blogic_qcmd_lck(). __assume_ctx_lock() should be avoided if
> possible because it defeats the purpose of compile-time thread-safety
> analysis.
> 
> The BusLogic driver is one of the few drivers that releases and
> reacquires shost->host_lock() from inside blogic_qcmd_lck(). Preventing
> that the Clang compiler complains about the spin_unlock_irq() and
> spin_lock_irq() calls in blogic_qcmd_lck() requires adding a
> __must_hold(&shost->host_lock) annotation to the blogic_qcmd_lck()
> function. And adding the __must_hold(&shost->host_lock) annotation
> to the blogic_qcmd_lck() function is only possible if 'shost' is one of
> the arguments of the blogic_qcmd_lck() function.

That is significant code change just to satisfy a code analysis tool. That
is making me uncomfortble to say the least. Even if DEF_SCSI_QCMD() has
not changed in 16 years, I am strongly in favor of using standard function
definitions especially when offered through a common macro for the subsystem
and in my opinion it also enforces the soft agreement on API between SCSI layers.

I am currently traveling without my laptop and it is hard for me to do proper
code review. I will get back to this in about 2 weeks.

Thanks,
Khalid