linux-kernel - [Question: devm_kfree] When should devm

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Message-ID: <20190528003257.GA12065@zhanggen-UX430UQ>
Date:   Tue, 28 May 2019 08:32:57 +0800
From:   Gen Zhang <blackgod016574@...il.com>
To:     gregkh@...uxfoundation.org, rafael@...nel.org,
        akpm@...ux-foundation.org
Cc:     linux-kernel@...r.kernel.org
Subject: [Question: devm_kfree] When should devm_kfree() be used?

devm_kmalloc() is used to allocate memory for a driver dev. Comments
above the definition and doc 
(https://www.kernel.org/doc/Documentation/driver-model/devres.txt) all
imply that allocated the memory is automatically freed on driver attach,
no matter allocation fail or not. However, I examined the code, and
there are many sites that devm_kfree() is used to free devm_kmalloc().
e.g. hisi_sas_debugfs_init() in drivers/scsi/hisi_sas/hisi_sas_main.c.
So I am totally confused about this issue. Can anybody give me some
guidance? When should we use devm_kfree()?

Thanks