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Fri, 29 Mar 2024 11:16:59 +0100 Received: from ukl by ptz.office.stw.pengutronix.de with local (Exim 4.96) (envelope-from ) id 1rq9IB-00DOxV-18; Fri, 29 Mar 2024 11:16:59 +0100 From: =?utf-8?q?Uwe_Kleine-K=C3=B6nig?= To: linux-pwm@vger.kernel.org, David Lechner Cc: kernel@pengutronix.de Subject: [PATCH] pwm: Don't check pointer for being non-NULL after use Date: Fri, 29 Mar 2024 11:16:48 +0100 Message-ID: <20240329101648.544155-2-u.kleine-koenig@pengutronix.de> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: linux-pwm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=1096; i=u.kleine-koenig@pengutronix.de; h=from:subject; bh=XL3poH2y8oEo0pLJCjDVIsvxBQ8qW/YAq8acjcctwRY=; b=owEBbQGS/pANAwAKAY+A+1h9Ev5OAcsmYgBmBpUQt/bAlbtOCdK99qXyjaQysFP4U5wnlFF1Z PMtdUOfQeSJATMEAAEKAB0WIQQ/gaxpOnoeWYmt/tOPgPtYfRL+TgUCZgaVEAAKCRCPgPtYfRL+ ThIvB/9k1FJsv72fn7e0/c5elbO0xHAZhZw6YEtka/bRrpkg4v4te3SrIHyU8A/Z1U0eEs47oFs 9XLIgzi9yeJzMnswgmzenGJ0uVPjVnEHH2B+DC3IHOBFug+iGzJZCW5hS2+t+6i4/XftUOYyZkN 7zNyjJ2B6blZsbq2ZvUmaixe0VNcbRFyHaKhEN/8Lh5dOLZq8KzZRB/WeTDVW+poyLcjuYP4BsU aXf2SKknRSz5PXPjabVBHakoOr7Y9SBiB8wwPd9f/q8jQKfqaDd4owezMcgAp84qLvpOZbwhW3O kBW24oiwrzs6JdozJnYsLTgarad2g1ePqDV6LBIfpOp7cCvS X-Developer-Key: i=u.kleine-koenig@pengutronix.de; a=openpgp; fpr=0D2511F322BFAB1C1580266BE2DCDD9132669BD6 X-SA-Exim-Connect-IP: 2a0a:edc0:0:c01:1d::a2 X-SA-Exim-Mail-From: ukl@pengutronix.de X-SA-Exim-Scanned: No (on metis.whiteo.stw.pengutronix.de); SAEximRunCond expanded to false X-PTX-Original-Recipient: linux-pwm@vger.kernel.org After assigning chip = pwm->chip; the compiler is free to assume that pwm is non-NULL and so can optimize out the check for pwm against NULL. While it's probably a programming error to pass a NULL pointer to pwm_put() this shouldn't be dropped without careful consideration and wasn't intended. So assign chip only after the NULL check. Reported-by: David Lechner Fixes: d60bc2995732 ("pwm: Add a struct device to struct pwm_chip") Signed-off-by: Uwe Kleine-König Reviewed-by: David Lechner --- drivers/pwm/core.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) base-commit: d60bc2995732489766cbe650fc367e036ff6a0e0 diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c index 7f41ab087b98..54a62879fffa 100644 --- a/drivers/pwm/core.c +++ b/drivers/pwm/core.c @@ -1866,11 +1866,13 @@ EXPORT_SYMBOL_GPL(pwm_get); */ void pwm_put(struct pwm_device *pwm) { - struct pwm_chip *chip = pwm->chip; + struct pwm_chip *chip; if (!pwm) return; + chip = pwm->chip; + mutex_lock(&pwm_lock); /*