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Date:   Wed, 19 May 2021 08:04:59 -0700
From:   Jeff Johnson <jjohnson@codeaurora.org>
To:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc:     linux-wireless@vger.kernel.org, Kalle Valo <kvalo@codeaurora.org>,
        "David S. Miller" <davem@davemloft.net>,
        Jakub Kicinski <kuba@kernel.org>,
        Kees Cook <keescook@chromium.org>,
        Jason Gunthorpe <jgg@ziepe.ca>, Chao Yu <chao@kernel.org>,
        Leon Romanovsky <leon@kernel.org>, b43-dev@lists.infradead.org,
        netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
        jjohnson=codeaurora.org@codeaurora.org
Subject: Re: [PATCH v2] b43: don't save dentries for debugfs
In-Reply-To: <YKScfFKhxtVqfRkt@kroah.com>
References: <20210518163304.3702015-1-gregkh@linuxfoundation.org>
 <891f28e4c1f3c24ed1b257de83cbb3a0@codeaurora.org>
 <f539277054c06e1719832b9e99cbf7f1@codeaurora.org>
 <YKScfFKhxtVqfRkt@kroah.com>
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On 2021-05-18 22:05, Greg Kroah-Hartman wrote:
> On Tue, May 18, 2021 at 03:00:44PM -0700, Jeff Johnson wrote:
>> On 2021-05-18 12:29, Jeff Johnson wrote:
>> Would still like guidance on if there is a recommended way to get a
>> dentry not associated with debugfs.
> 
> What do you exactly mean by "not associated with debugfs"?
> 
> And why are you passing a debugfs dentry to relay_open()?  That feels
> really wrong and fragile.

I don't know the history but the relay documentation tells us:
"If you want a directory structure to contain your relay files,
you should create it using the host filesystem’s directory
creation function, e.g. debugfs_create_dir()..."

So my guess is that the original implementation followed that
advice.  I see 5 clients of this functionality, and all 5 pass a
dentry returned from debugfs_create_dir():

drivers/gpu/drm/i915/gt/uc/intel_guc_log.c, line 384
drivers/net/wireless/ath/ath10k/spectral.c, line 534
drivers/net/wireless/ath/ath11k/spectral.c, line 902
drivers/net/wireless/ath/ath9k/common-spectral.c, line 1077
kernel/trace/blktrace.c, line 549

Jeff
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