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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>,
	linux-wireless@vger.kernel.org, linux-kernel@vger.kernel.org,
	QCA ath9k Development <ath9k-devel@qca.qualcomm.com>,
	netdev@vger.kernel.org, linux-pci@vger.kernel.org,
	linux-kernel-mentees@lists.linuxfoundation.org
Subject: [Linux-kernel-mentees] [PATCH v4 03/12] ath9k: Check if pcie_capability_read_*() reads ~0
Date: Fri, 31 Jul 2020 13:02:31 +0200	[thread overview]
Message-ID: <20200731110240.98326-4-refactormyself@gmail.com> (raw)
In-Reply-To: <20200731110240.98326-1-refactormyself@gmail.com>

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

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  parent reply	other threads:[~2020-07-31 12:02 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-31 11:02 [Linux-kernel-mentees] [PATCH v4 00/12] PCI: Remove '*val = 0' from pcie_capability_read_*() Saheed O. Bolarinwa
2020-07-31 11:02 ` [Linux-kernel-mentees] [PATCH v4 01/12] IB/hfi1: Check if pcie_capability_read_*() reads ~0 Saheed O. Bolarinwa
2020-07-31 13:55   ` Bjorn Helgaas
2020-08-03 11:46     ` Ian Kumlien
2020-07-31 11:02 ` [Linux-kernel-mentees] [PATCH v4 02/12] misc: rtsx: " Saheed O. Bolarinwa
2020-07-31 11:02 ` Saheed O. Bolarinwa [this message]
2020-07-31 11:02 ` [Linux-kernel-mentees] [PATCH v4 04/12] iwlegacy: " Saheed O. Bolarinwa
2020-07-31 11:02 ` [Linux-kernel-mentees] [PATCH v4 05/12] PCI: pciehp: Set "Power On" as the default get_power_status Saheed O. Bolarinwa
2020-07-31 11:02 ` [Linux-kernel-mentees] [PATCH v4 06/12] PCI: pciehp: Check if pcie_capability_read_*() reads ~0 Saheed O. Bolarinwa
2020-07-31 11:02 ` [Linux-kernel-mentees] [PATCH v4 07/12] PCI/ACPI: " Saheed O. Bolarinwa

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