Patch "net: ethernet: stmmac: Do not use unreachable() in ipq806x_gmac_probe()" has been added to the 4.19-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    net: ethernet: stmmac: Do not use unreachable() in ipq806x_gmac_probe()

to the 4.19-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     net-ethernet-stmmac-do-not-use-unreachable-in-ipq806.patch
and it can be found in the queue-4.19 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 9c0c25f059f5765799b19b17f997ad75c4392312
Author: Nathan Chancellor <nathan@xxxxxxxxxx>
Date:   Fri Aug 6 12:13:40 2021 -0700

    net: ethernet: stmmac: Do not use unreachable() in ipq806x_gmac_probe()
    
    [ Upstream commit 4367355dd90942a71641c98c40c74589c9bddf90 ]
    
    When compiling with clang in certain configurations, an objtool warning
    appears:
    
    drivers/net/ethernet/stmicro/stmmac/dwmac-ipq806x.o: warning: objtool:
    ipq806x_gmac_probe() falls through to next function phy_modes()
    
    This happens because the unreachable annotation in the third switch
    statement is not eliminated. The compiler should know that the first
    default case would prevent the second and third from being reached as
    the comment notes but sanitizer options can make it harder for the
    compiler to reason this out.
    
    Help the compiler out by eliminating the unreachable() annotation and
    unifying the default case error handling so that there is no objtool
    warning, the meaning of the code stays the same, and there is less
    duplication.
    
    Reported-by: Sami Tolvanen <samitolvanen@xxxxxxxxxx>
    Tested-by: Sami Tolvanen <samitolvanen@xxxxxxxxxx>
    Signed-off-by: Nathan Chancellor <nathan@xxxxxxxxxx>
    Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac-ipq806x.c b/drivers/net/ethernet/stmicro/stmmac/dwmac-ipq806x.c
index 0f56f8e33691..03b11f191c26 100644
--- a/drivers/net/ethernet/stmicro/stmmac/dwmac-ipq806x.c
+++ b/drivers/net/ethernet/stmicro/stmmac/dwmac-ipq806x.c
@@ -288,10 +288,7 @@ static int ipq806x_gmac_probe(struct platform_device *pdev)
 		val &= ~NSS_COMMON_GMAC_CTL_PHY_IFACE_SEL;
 		break;
 	default:
-		dev_err(&pdev->dev, "Unsupported PHY mode: \"%s\"\n",
-			phy_modes(gmac->phy_mode));
-		err = -EINVAL;
-		goto err_remove_config_dt;
+		goto err_unsupported_phy;
 	}
 	regmap_write(gmac->nss_common, NSS_COMMON_GMAC_CTL(gmac->id), val);
 
@@ -308,10 +305,7 @@ static int ipq806x_gmac_probe(struct platform_device *pdev)
 			NSS_COMMON_CLK_SRC_CTRL_OFFSET(gmac->id);
 		break;
 	default:
-		dev_err(&pdev->dev, "Unsupported PHY mode: \"%s\"\n",
-			phy_modes(gmac->phy_mode));
-		err = -EINVAL;
-		goto err_remove_config_dt;
+		goto err_unsupported_phy;
 	}
 	regmap_write(gmac->nss_common, NSS_COMMON_CLK_SRC_CTRL, val);
 
@@ -328,8 +322,7 @@ static int ipq806x_gmac_probe(struct platform_device *pdev)
 				NSS_COMMON_CLK_GATE_GMII_TX_EN(gmac->id);
 		break;
 	default:
-		/* We don't get here; the switch above will have errored out */
-		unreachable();
+		goto err_unsupported_phy;
 	}
 	regmap_write(gmac->nss_common, NSS_COMMON_CLK_GATE, val);
 
@@ -360,6 +353,11 @@ static int ipq806x_gmac_probe(struct platform_device *pdev)
 
 	return 0;
 
+err_unsupported_phy:
+	dev_err(&pdev->dev, "Unsupported PHY mode: \"%s\"\n",
+		phy_modes(gmac->phy_mode));
+	err = -EINVAL;
+
 err_remove_config_dt:
 	stmmac_remove_config_dt(pdev, plat_dat);