From: Saheed Olayemi Bolarinwa <refactormyself@gmail.com> To: helgaas@kernel.org Cc: Bolarinwa Olayemi Saheed <refactormyself@gmail.com>, bjorn@helgaas.com, skhan@linuxfoundation.org, linux-pci@vger.kernel.org, linux-kernel-mentees@lists.linuxfoundation.org, linux-kernel@vger.kernel.org Subject: [PATCH 7/14 v3] PCI: pciehp: Check the return value of pcie_capability_read_*() Date: Fri, 10 Jul 2020 23:20:19 +0200 [thread overview] Message-ID: <20200710212026.27136-8-refactormyself@gmail.com> (raw) In-Reply-To: <20200710212026.27136-1-refactormyself@gmail.com> From: Bolarinwa Olayemi Saheed <refactormyself@gmail.com> If pcie_capability_read_word() fail, slot_ctrl will be 0 and the switch expression evaluates to 0. So *status = 1 "ON". However, with Patch 14/14 it is possible that slot_ctrl is set to ~0 on failure. This would introduce a bug because (x & x) == (~0 & x), so the switch expression evaluates to PCI_EXP_SLTCTL_PCC. This means that on failure *status = 1 "OFF", since PCI_EXP_SLTCTL_PCC = PCI_EXP_SLTCTL_PWR_OFF. Use an if-statement and include a check on the return value of pcie_capability_read_word() to confirm success or failure. Suggested-by: Bjorn Helgaas <bjorn@helgaas.com> Signed-off-by: Bolarinwa Olayemi Saheed <refactormyself@gmail.com> --- drivers/pci/hotplug/pciehp_hpc.c | 14 +++++--------- 1 file changed, 5 insertions(+), 9 deletions(-) diff --git a/drivers/pci/hotplug/pciehp_hpc.c b/drivers/pci/hotplug/pciehp_hpc.c index b89c9ee4a3b5..f5ef3fbace69 100644 --- a/drivers/pci/hotplug/pciehp_hpc.c +++ b/drivers/pci/hotplug/pciehp_hpc.c @@ -394,20 +394,16 @@ void pciehp_get_power_status(struct controller *ctrl, u8 *status) { struct pci_dev *pdev = ctrl_dev(ctrl); u16 slot_ctrl; + int ret; - pcie_capability_read_word(pdev, PCI_EXP_SLTCTL, &slot_ctrl); + *status = 1; /* On */ + ret = pcie_capability_read_word(pdev, PCI_EXP_SLTCTL, &slot_ctrl); ctrl_dbg(ctrl, "%s: SLOTCTRL %x value read %x\n", __func__, pci_pcie_cap(ctrl->pcie->port) + PCI_EXP_SLTCTL, slot_ctrl); - switch (slot_ctrl & PCI_EXP_SLTCTL_PCC) { - case PCI_EXP_SLTCTL_PWR_OFF: + if (!ret && + ((slot_ctrl & PCI_EXP_SLTCTL_PCC) == PCI_EXP_SLTCTL_PWR_OFF)) *status = 0; /* Off */ - break; - case PCI_EXP_SLTCTL_PWR_ON: - default: - *status = 1; /* On */ - break; - } } void pciehp_get_latch_status(struct controller *ctrl, u8 *status) -- 2.18.2
WARNING: multiple messages have this Message-ID (diff)
From: Saheed Olayemi Bolarinwa <refactormyself@gmail.com> To: helgaas@kernel.org Cc: Bolarinwa Olayemi Saheed <refactormyself@gmail.com>, linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org, linux-kernel-mentees@lists.linuxfoundation.org Subject: [Linux-kernel-mentees] [PATCH 7/14 v3] PCI: pciehp: Check the return value of pcie_capability_read_*() Date: Fri, 10 Jul 2020 23:20:19 +0200 [thread overview] Message-ID: <20200710212026.27136-8-refactormyself@gmail.com> (raw) In-Reply-To: <20200710212026.27136-1-refactormyself@gmail.com> From: Bolarinwa Olayemi Saheed <refactormyself@gmail.com> If pcie_capability_read_word() fail, slot_ctrl will be 0 and the switch expression evaluates to 0. So *status = 1 "ON". However, with Patch 14/14 it is possible that slot_ctrl is set to ~0 on failure. This would introduce a bug because (x & x) == (~0 & x), so the switch expression evaluates to PCI_EXP_SLTCTL_PCC. This means that on failure *status = 1 "OFF", since PCI_EXP_SLTCTL_PCC = PCI_EXP_SLTCTL_PWR_OFF. Use an if-statement and include a check on the return value of pcie_capability_read_word() to confirm success or failure. Suggested-by: Bjorn Helgaas <bjorn@helgaas.com> Signed-off-by: Bolarinwa Olayemi Saheed <refactormyself@gmail.com> --- drivers/pci/hotplug/pciehp_hpc.c | 14 +++++--------- 1 file changed, 5 insertions(+), 9 deletions(-) diff --git a/drivers/pci/hotplug/pciehp_hpc.c b/drivers/pci/hotplug/pciehp_hpc.c index b89c9ee4a3b5..f5ef3fbace69 100644 --- a/drivers/pci/hotplug/pciehp_hpc.c +++ b/drivers/pci/hotplug/pciehp_hpc.c @@ -394,20 +394,16 @@ void pciehp_get_power_status(struct controller *ctrl, u8 *status) { struct pci_dev *pdev = ctrl_dev(ctrl); u16 slot_ctrl; + int ret; - pcie_capability_read_word(pdev, PCI_EXP_SLTCTL, &slot_ctrl); + *status = 1; /* On */ + ret = pcie_capability_read_word(pdev, PCI_EXP_SLTCTL, &slot_ctrl); ctrl_dbg(ctrl, "%s: SLOTCTRL %x value read %x\n", __func__, pci_pcie_cap(ctrl->pcie->port) + PCI_EXP_SLTCTL, slot_ctrl); - switch (slot_ctrl & PCI_EXP_SLTCTL_PCC) { - case PCI_EXP_SLTCTL_PWR_OFF: + if (!ret && + ((slot_ctrl & PCI_EXP_SLTCTL_PCC) == PCI_EXP_SLTCTL_PWR_OFF)) *status = 0; /* Off */ - break; - case PCI_EXP_SLTCTL_PWR_ON: - default: - *status = 1; /* On */ - break; - } } void pciehp_get_latch_status(struct controller *ctrl, u8 *status) -- 2.18.2 _______________________________________________ Linux-kernel-mentees mailing list Linux-kernel-mentees@lists.linuxfoundation.org https://lists.linuxfoundation.org/mailman/listinfo/linux-kernel-mentees
next prev parent reply other threads:[~2020-07-10 22:20 UTC|newest] Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-07-10 21:20 [PATCH 0/14 v3] PCI: Remove '*val = 0' from pcie_capability_read_*() Saheed Olayemi Bolarinwa 2020-07-10 21:20 ` [Linux-kernel-mentees] " Saheed Olayemi Bolarinwa 2020-07-10 21:20 ` Saheed Olayemi Bolarinwa 2020-07-10 21:20 ` [PATCH 2/14 v3] misc: rtsx: Check the return value of pcie_capability_read_*() Saheed Olayemi Bolarinwa 2020-07-10 21:20 ` [Linux-kernel-mentees] " Saheed Olayemi Bolarinwa 2020-07-10 21:20 ` [PATCH 5/14 v3] PCI: pciehp: " Saheed Olayemi Bolarinwa 2020-07-10 21:20 ` [Linux-kernel-mentees] " Saheed Olayemi Bolarinwa 2020-07-10 21:20 ` [PATCH 6/14 v3] PCI: pciehp: Make "Power On" the default Saheed Olayemi Bolarinwa 2020-07-10 21:20 ` [Linux-kernel-mentees] " Saheed Olayemi Bolarinwa 2020-07-10 21:20 ` Saheed Olayemi Bolarinwa [this message] 2020-07-10 21:20 ` [Linux-kernel-mentees] [PATCH 7/14 v3] PCI: pciehp: Check the return value of pcie_capability_read_*() Saheed Olayemi Bolarinwa 2020-07-10 21:20 ` [PATCH 9/14 v3] PCI: pciehp: Check " Saheed Olayemi Bolarinwa 2020-07-10 21:20 ` [Linux-kernel-mentees] " Saheed Olayemi Bolarinwa 2020-07-10 21:20 ` [PATCH 10/14 v3] PCI: " Saheed Olayemi Bolarinwa 2020-07-10 21:20 ` [Linux-kernel-mentees] " Saheed Olayemi Bolarinwa 2020-07-10 21:20 ` [PATCH 11/14 v3] PCI/PM: " Saheed Olayemi Bolarinwa 2020-07-10 21:20 ` [Linux-kernel-mentees] " Saheed Olayemi Bolarinwa 2020-07-14 8:10 ` David Laight 2020-07-14 8:10 ` [Linux-kernel-mentees] " David Laight 2020-07-10 21:20 ` [PATCH 13/14] PCI/ASPM: Check the " Saheed Olayemi Bolarinwa 2020-07-10 21:20 ` [Linux-kernel-mentees] " Saheed Olayemi Bolarinwa 2020-07-10 21:20 ` [PATCH 14/14 v3] PCI: Remove '*val = 0' from pcie_capability_read_*() Saheed Olayemi Bolarinwa 2020-07-10 21:20 ` [Linux-kernel-mentees] " Saheed Olayemi Bolarinwa 2020-07-10 21:20 ` Saheed Olayemi Bolarinwa [not found] ` <20200710212026.27136-5-refactormyself@gmail.com> 2020-07-13 13:44 ` [PATCH 4/14 v3] iwlegacy: Check the return value of pcie_capability_read_*() Kalle Valo 2020-07-13 18:02 ` Saheed Bolarinwa
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