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R. Silva" Cc: linux-kernel@vger.kernel.org, kernel-janitors@vger.kernel.org, Christophe JAILLET , linux-hardening@vger.kernel.org Subject: [PATCH 1/2] mux: Turn 'mux' into a flexible array in 'struct mux_chip' Date: Sun, 26 Nov 2023 09:08:11 +0100 Message-Id: X-Mailer: git-send-email 2.34.1 MIME-Version: 1.0 X-Spam-Status: No, score=-0.9 required=5.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,T_SCC_BODY_TEXT_LINE autolearn=unavailable autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on morse.vger.email Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-Greylist: Sender passed SPF test, not delayed by milter-greylist-4.6.4 (morse.vger.email [0.0.0.0]); Sun, 26 Nov 2023 00:08:52 -0800 (PST) X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: 1783613240682243867 X-GMAIL-MSGID: 1783613240682243867 The 'mux' array stored in 'struct mux_chip' can be changed into a flexible array. This saves: - a pointer in the structure - an indirection when accessing the array - some pointer arithmetic when computing and storing the address in 'mux' It is also now possible to use __counted_by() and struct_size() for additional safety. The address for the 'priv' memory is computed with mux_chip_priv(). It should work as good with a flexible array. Signed-off-by: Christophe JAILLET --- The struct_size() goodies only work if sizeof_priv is 0. Adding an additional size_add() would make it safe in all cases but would make code less readable (IMHO). --- drivers/mux/core.c | 4 +--- include/linux/mux/driver.h | 5 +++-- 2 files changed, 4 insertions(+), 5 deletions(-) diff --git a/drivers/mux/core.c b/drivers/mux/core.c index 775816112932..80b2607b083b 100644 --- a/drivers/mux/core.c +++ b/drivers/mux/core.c @@ -98,13 +98,11 @@ struct mux_chip *mux_chip_alloc(struct device *dev, if (WARN_ON(!dev || !controllers)) return ERR_PTR(-EINVAL); - mux_chip = kzalloc(sizeof(*mux_chip) + - controllers * sizeof(*mux_chip->mux) + + mux_chip = kzalloc(struct_size(mux_chip, mux, controllers) + sizeof_priv, GFP_KERNEL); if (!mux_chip) return ERR_PTR(-ENOMEM); - mux_chip->mux = (struct mux_control *)(mux_chip + 1); mux_chip->dev.class = &mux_class; mux_chip->dev.type = &mux_type; mux_chip->dev.parent = dev; diff --git a/include/linux/mux/driver.h b/include/linux/mux/driver.h index 18824064f8c0..c29e9b7fb17b 100644 --- a/include/linux/mux/driver.h +++ b/include/linux/mux/driver.h @@ -56,18 +56,19 @@ struct mux_control { /** * struct mux_chip - Represents a chip holding mux controllers. * @controllers: Number of mux controllers handled by the chip. - * @mux: Array of mux controllers that are handled. * @dev: Device structure. * @id: Used to identify the device internally. * @ops: Mux controller operations. + * @mux: Array of mux controllers that are handled. */ struct mux_chip { unsigned int controllers; - struct mux_control *mux; struct device dev; int id; const struct mux_control_ops *ops; + + struct mux_control mux[] __counted_by(controllers); }; #define to_mux_chip(x) container_of((x), struct mux_chip, dev)