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Date: Tue, 7 May 2024 13:27:02 -0300
From: Jason Gunthorpe <jgg@ziepe.ca>
To: Zong Li <zong.li@sifive.com>
Cc: joro@8bytes.org, will@kernel.org, robin.murphy@arm.com,
	tjeznach@rivosinc.com, paul.walmsley@sifive.com, palmer@dabbelt.com,
	aou@eecs.berkeley.edu, kevin.tian@intel.com,
	linux-kernel@vger.kernel.org, iommu@lists.linux.dev,
	linux-riscv@lists.infradead.org
Subject: Re: [PATCH RFC RESEND 6/6] iommu/riscv: support nested iommu for
 flushing cache
Message-ID: <20240507162702.GC4718@ziepe.ca>
References: <20240507142600.23844-1-zong.li@sifive.com>
 <20240507142600.23844-7-zong.li@sifive.com>
 <20240507150829.GJ901876@ziepe.ca>
 <CANXhq0rnWUT4ia-cUoTbSyEQUeCcmC9bC7HHru6Se-1K-PZRDQ@mail.gmail.com>
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On Tue, May 07, 2024 at 11:35:16PM +0800, Zong Li wrote:
> > > +     default:
> > > +             pr_warn("The user command: 0x%x is not supported\n", opcode);
> > > +             return -EOPNOTSUPP;
> >
> > No userspace triggerable warnings.
> 
> I don't complete understand about this. Could I know whether we should
> suppress the message and return the error directly, or if we should
> convert the warning to an error (i.e. pr_err)?

A userspace system call should never print to dmesg. Return an error
code. Put a pr_debug if you really care.

Jason