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From:   "Saheed O. Bolarinwa" <refactormyself@gmail.com>
To:     helgaas@kernel.org, "David S. Miller" <davem@davemloft.net>,
        Kalle Valo <kvalo@codeaurora.org>,
        Jakub Kicinski <kuba@kernel.org>
Cc:     "Saheed O. Bolarinwa" <refactormyself@gmail.com>,
        bjorn@helgaas.com, skhan@linuxfoundation.org,
        linux-kernel-mentees@lists.linuxfoundation.org,
        linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org,
        QCA ath9k Development <ath9k-devel@qca.qualcomm.com>,
        linux-wireless@vger.kernel.org, netdev@vger.kernel.org
Subject: [PATCH v4 03/12] ath9k: Check if pcie_capability_read_*() reads ~0
Date:   Fri, 31 Jul 2020 13:02:31 +0200
Message-Id: <20200731110240.98326-4-refactormyself@gmail.com>
In-Reply-To: <20200731110240.98326-1-refactormyself@gmail.com>
References: <20200731110240.98326-1-refactormyself@gmail.com>
Sender: linux-wireless-owner@vger.kernel.org
Precedence: bulk

On failure pcie_capability_read_dword() sets it's last parameter, val
to 0. However, with Patch 12/12, it is possible that val is set to ~0
on failure. This would introduce a bug because (x & x) == (~0 & x).

Since ~0 is an invalid value here,

Add an extra check for ~0 to the if condition to ensure success.

Suggested-by: Bjorn Helgaas <bjorn@helgaas.com>
Signed-off-by: Saheed O. Bolarinwa <refactormyself@gmail.com>
---
 drivers/net/wireless/ath/ath9k/pci.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/net/wireless/ath/ath9k/pci.c b/drivers/net/wireless/ath/ath9k/pci.c
index f3461b193c7a..f02b243befef 100644
--- a/drivers/net/wireless/ath/ath9k/pci.c
+++ b/drivers/net/wireless/ath/ath9k/pci.c
@@ -867,7 +867,8 @@ static void ath_pci_aspm_init(struct ath_common *common)
 		pci_read_config_dword(pdev, 0x70c, &ah->config.aspm_l1_fix);
 
 	pcie_capability_read_word(parent, PCI_EXP_LNKCTL, &aspm);
-	if (aspm & (PCI_EXP_LNKCTL_ASPM_L0S | PCI_EXP_LNKCTL_ASPM_L1)) {
+	if ((aspm != (u16)~0) &&
+	    (aspm & (PCI_EXP_LNKCTL_ASPM_L0S | PCI_EXP_LNKCTL_ASPM_L1))) {
 		ah->aspm_enabled = true;
 		/* Initialize PCIe PM and SERDES registers. */
 		ath9k_hw_configpcipowersave(ah, false);
-- 
2.18.4