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[2.34.30.183]) by smtp.gmail.com with ESMTPSA id d24-20020ac84e38000000b003a7e38055c9sm3296441qtw.63.2023.01.25.06.06.34 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 25 Jan 2023 06:06:35 -0800 (PST) From: Marco Pagani To: Moritz Fischer , Wu Hao , Xu Yilun , Tom Rix Cc: Marco Pagani , linux-fpga@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH] fpga: bridge: return errors in the show() method of the "state" attribute Date: Wed, 25 Jan 2023 15:06:22 +0100 Message-Id: <20230125140622.176870-1-marpagan@redhat.com> X-Mailer: git-send-email 2.39.1 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-fpga@vger.kernel.org This patch changes the show() method of the "state" sysfs attribute to propagate errors returned by the enable_show() op. In this way, userspace can distinguish between when the bridge is actually "enabled" (i.e., allowing signals) or "disabled" (i.e., gating signals), or when there is an error. Currently, enable_show() returns an integer representing the bridge's state (enabled or disabled) or an error code. However, this integer value is interpreted in state_show() as a bool, resulting in the method printing "enabled" (i.e., the bridge allows signals to pass), without propagating the error, even when enable_show() returns an error code. Thanks Signed-off-by: Marco Pagani Acked-by: Xu Yilun --- drivers/fpga/fpga-bridge.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) diff --git a/drivers/fpga/fpga-bridge.c b/drivers/fpga/fpga-bridge.c index 727704431f61..5cd40acab5bf 100644 --- a/drivers/fpga/fpga-bridge.c +++ b/drivers/fpga/fpga-bridge.c @@ -293,12 +293,15 @@ static ssize_t state_show(struct device *dev, struct device_attribute *attr, char *buf) { struct fpga_bridge *bridge = to_fpga_bridge(dev); - int enable = 1; + int state = 1; - if (bridge->br_ops && bridge->br_ops->enable_show) - enable = bridge->br_ops->enable_show(bridge); + if (bridge->br_ops && bridge->br_ops->enable_show) { + state = bridge->br_ops->enable_show(bridge); + if (state < 0) + return state; + } - return sprintf(buf, "%s\n", enable ? "enabled" : "disabled"); + return sysfs_emit(buf, "%s\n", state ? "enabled" : "disabled"); } static DEVICE_ATTR_RO(name);