linux-kernel - [PATCH 03/11] nvmem: specify ->reg_read/reg

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20241230143035.265518-4-srinivas.kandagatla@linaro.org>
Date: Mon, 30 Dec 2024 14:30:27 +0000
From: srinivas.kandagatla@...aro.org
To: gregkh@...uxfoundation.org
Cc: linux-kernel@...r.kernel.org,
	Théo Lebrun <theo.lebrun@...tlin.com>,
	Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
Subject: [PATCH 03/11] nvmem: specify ->reg_read/reg_write() expected return values

From: Théo Lebrun <theo.lebrun@...tlin.com>

Both ->reg_read() and ->reg_write() return values are not easy to
deduce. Explicit that they should return zero on success (and negative
values otherwise).

Such callbacks, in some alternative world, could return the number of
bytes in the success case. That would be translated to errors in the
nvmem core because of checks like:

	ret = nvmem->reg_write(nvmem->priv, offset, val, bytes);
	if (ret) {
		// error case
	}

This mistake is not just theoretical, see commit
28b008751aa2 ("nvmem: rmem: Fix return value of rmem_read()").

Signed-off-by: Théo Lebrun <theo.lebrun@...tlin.com>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
---
 include/linux/nvmem-provider.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/include/linux/nvmem-provider.h b/include/linux/nvmem-provider.h
index 3ebeaa0ded00..515676ebe598 100644
--- a/include/linux/nvmem-provider.h
+++ b/include/linux/nvmem-provider.h
@@ -92,8 +92,8 @@ struct nvmem_cell_info {
  * @read_only:	Device is read-only.
  * @root_only:	Device is accessibly to root only.
  * @of_node:	If given, this will be used instead of the parent's of_node.
- * @reg_read:	Callback to read data.
- * @reg_write:	Callback to write data.
+ * @reg_read:	Callback to read data; return zero if successful.
+ * @reg_write:	Callback to write data; return zero if successful.
  * @size:	Device size.
  * @word_size:	Minimum read/write access granularity.
  * @stride:	Minimum read/write access stride.
-- 
2.25.1