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From: Arnd Bergmann <arnd@kernel.org>
To: Sudeep Holla <sudeep.holla@arm.com>,
	Cristian Marussi <cristian.marussi@arm.com>
Cc: Arnd Bergmann <arnd@arndb.de>,
	Nathan Chancellor <nathan@kernel.org>,
	Nick Desaulniers <ndesaulniers@google.com>,
	Bill Wendling <morbo@google.com>,
	Justin Stitt <justinstitt@google.com>,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org,
	llvm@lists.linux.dev
Subject: [PATCH] firmware: arm_scmi: avoid returning uninialized data
Date: Fri, 16 Feb 2024 17:32:53 +0100
Message-Id: <20240216163259.1927967-1-arnd@kernel.org>
Precedence: bulk
MIME-Version: 1.0
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From: Arnd Bergmann <arnd@arndb.de>

Clang notices that there is a code path through
scmi_powercap_notify_supported() that returns an
undefined value:

drivers/firmware/arm_scmi/powercap.c:821:11: error: variable 'supported' is used uninitialized whenever 'if' condition is false [-Werror,-Wsometimes-uninitialized]
  821 |         else if (evt_id == SCMI_EVENT_POWERCAP_MEASUREMENTS_CHANGED)
      |                  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
drivers/firmware/arm_scmi/powercap.c:824:9: note: uninitialized use occurs here
  824 |         return supported;
      |                ^~~~~~~~~
drivers/firmware/arm_scmi/powercap.c:821:7: note: remove the 'if' if its condition is always true
  821 |         else if (evt_id == SCMI_EVENT_POWERCAP_MEASUREMENTS_CHANGED)
      |              ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  822 |                 supported = dom_info->notify_powercap_measurement_change;
drivers/firmware/arm_scmi/powercap.c:811:16: note: initialize the variable 'supported' to silence this warning
  811 |         bool supported;
      |                       ^

Return 'false' here, which is probably what was intended.

Fixes: c92a75fe84ce ("firmware: arm_scmi: Implement Powercap .is_notify_supported callback")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 drivers/firmware/arm_scmi/powercap.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/firmware/arm_scmi/powercap.c b/drivers/firmware/arm_scmi/powercap.c
index aae91f47303e..8ee3be8776b0 100644
--- a/drivers/firmware/arm_scmi/powercap.c
+++ b/drivers/firmware/arm_scmi/powercap.c
@@ -820,6 +820,8 @@ scmi_powercap_notify_supported(const struct scmi_protocol_handle *ph,
 		supported = dom_info->notify_powercap_cap_change;
 	else if (evt_id == SCMI_EVENT_POWERCAP_MEASUREMENTS_CHANGED)
 		supported = dom_info->notify_powercap_measurement_change;
+	else
+		supported = false;
 
 	return supported;
 }
-- 
2.39.2