| Message ID | 20200619201219.32126-3-refactormyself@gmail.com |
|---|---|
| State | New |
| Headers | show |
| Series | Fix wrong failure check on pcie_capability_read_*() | expand |
On Fri, Jun 19, 2020 at 10:12:19PM +0200, refactormyself@gmail.com wrote: > On failure, pcie_capabiility_read_*() will set the status value, > its last parameter to 0 and not ~0. > This bug fix checks for the proper value. If a config space read times out, the PCIe controller fabricates an "all ones" response. The code is checking for such a timeout, not for an error. Hence the code is fine. Thanks, Lukas > > Signed-off-by: Bolarinwa Olayemi Saheed <refactormyself@gmail.com> > --- > drivers/pci/hotplug/pciehp_hpc.c | 10 +++++----- > 1 file changed, 5 insertions(+), 5 deletions(-) > > diff --git a/drivers/pci/hotplug/pciehp_hpc.c b/drivers/pci/hotplug/pciehp_hpc.c > index 53433b37e181..c1a67054948a 100644 > --- a/drivers/pci/hotplug/pciehp_hpc.c > +++ b/drivers/pci/hotplug/pciehp_hpc.c > @@ -89,7 +89,7 @@ static int pcie_poll_cmd(struct controller *ctrl, int timeout) > > do { > pcie_capability_read_word(pdev, PCI_EXP_SLTSTA, &slot_status); > - if (slot_status == (u16) ~0) { > + if (slot_status == (u16)0) { > ctrl_info(ctrl, "%s: no response from device\n", > __func__); > return 0; > @@ -165,7 +165,7 @@ static void pcie_do_write_cmd(struct controller *ctrl, u16 cmd, > pcie_wait_cmd(ctrl); > > pcie_capability_read_word(pdev, PCI_EXP_SLTCTL, &slot_ctrl); > - if (slot_ctrl == (u16) ~0) { > + if (slot_ctrl == (u16)0) { > ctrl_info(ctrl, "%s: no response from device\n", __func__); > goto out; > } > @@ -236,7 +236,7 @@ int pciehp_check_link_active(struct controller *ctrl) > int ret; > > ret = pcie_capability_read_word(pdev, PCI_EXP_LNKSTA, &lnk_status); > - if (ret == PCIBIOS_DEVICE_NOT_FOUND || lnk_status == (u16)~0) > + if (ret == PCIBIOS_DEVICE_NOT_FOUND || lnk_status == (u16)0) > return -ENODEV; > > ret = !!(lnk_status & PCI_EXP_LNKSTA_DLLLA); > @@ -440,7 +440,7 @@ int pciehp_card_present(struct controller *ctrl) > int ret; > > ret = pcie_capability_read_word(pdev, PCI_EXP_SLTSTA, &slot_status); > - if (ret == PCIBIOS_DEVICE_NOT_FOUND || slot_status == (u16)~0) > + if (ret == PCIBIOS_DEVICE_NOT_FOUND || slot_status == (u16)0) > return -ENODEV; > > return !!(slot_status & PCI_EXP_SLTSTA_PDS); > @@ -592,7 +592,7 @@ static irqreturn_t pciehp_isr(int irq, void *dev_id) > > read_status: > pcie_capability_read_word(pdev, PCI_EXP_SLTSTA, &status); > - if (status == (u16) ~0) { > + if (status == (u16)0) { > ctrl_info(ctrl, "%s: no response from device\n", __func__); > if (parent) > pm_runtime_put(parent); > -- > 2.18.2
On Sat, Jun 20, 2020 at 11:09:36AM +0200, Lukas Wunner wrote: > On Fri, Jun 19, 2020 at 10:12:19PM +0200, refactormyself@gmail.com wrote: > > On failure, pcie_capabiility_read_*() will set the status value, > > its last parameter to 0 and not ~0. > > This bug fix checks for the proper value. > > If a config space read times out, the PCIe controller fabricates > an "all ones" response. The code is checking for such a timeout, > not for an error. Hence the code is fine. In the typical case, the pci_read_config_word() done by pcie_capability_read_word() will not return an error, so if the read times out, we should see slot_status == ~0. But if it's possible to set dev->error_state == pci_channel_io_perm_failure, pci_read_config_word() will return an error because pci_dev_is_disconnected(), so slot_status would be 0. There are a dozen or so places that set dev->error_state. It doesn't look *likely* that any of them would cause this, but it doesn't instill confidence. It would be a lot nicer if we didn't have to worry about both the 0 and ~0 cases. I keep coming back to the idea of removing the "*val = 0" code from pcie_capability_read_word() so we wouldn't have that special case. In any case, this particular patch doesn't seem like quite the right fix, so I'll drop it. > > Signed-off-by: Bolarinwa Olayemi Saheed <refactormyself@gmail.com> > > --- > > drivers/pci/hotplug/pciehp_hpc.c | 10 +++++----- > > 1 file changed, 5 insertions(+), 5 deletions(-) > > > > diff --git a/drivers/pci/hotplug/pciehp_hpc.c b/drivers/pci/hotplug/pciehp_hpc.c > > index 53433b37e181..c1a67054948a 100644 > > --- a/drivers/pci/hotplug/pciehp_hpc.c > > +++ b/drivers/pci/hotplug/pciehp_hpc.c > > @@ -89,7 +89,7 @@ static int pcie_poll_cmd(struct controller *ctrl, int timeout) > > > > do { > > pcie_capability_read_word(pdev, PCI_EXP_SLTSTA, &slot_status); > > - if (slot_status == (u16) ~0) { > > + if (slot_status == (u16)0) { > > ctrl_info(ctrl, "%s: no response from device\n", > > __func__); > > return 0; > > @@ -165,7 +165,7 @@ static void pcie_do_write_cmd(struct controller *ctrl, u16 cmd, > > pcie_wait_cmd(ctrl); > > > > pcie_capability_read_word(pdev, PCI_EXP_SLTCTL, &slot_ctrl); > > - if (slot_ctrl == (u16) ~0) { > > + if (slot_ctrl == (u16)0) { > > ctrl_info(ctrl, "%s: no response from device\n", __func__); > > goto out; > > } > > @@ -236,7 +236,7 @@ int pciehp_check_link_active(struct controller *ctrl) > > int ret; > > > > ret = pcie_capability_read_word(pdev, PCI_EXP_LNKSTA, &lnk_status); > > - if (ret == PCIBIOS_DEVICE_NOT_FOUND || lnk_status == (u16)~0) > > + if (ret == PCIBIOS_DEVICE_NOT_FOUND || lnk_status == (u16)0) > > return -ENODEV; > > > > ret = !!(lnk_status & PCI_EXP_LNKSTA_DLLLA); > > @@ -440,7 +440,7 @@ int pciehp_card_present(struct controller *ctrl) > > int ret; > > > > ret = pcie_capability_read_word(pdev, PCI_EXP_SLTSTA, &slot_status); > > - if (ret == PCIBIOS_DEVICE_NOT_FOUND || slot_status == (u16)~0) > > + if (ret == PCIBIOS_DEVICE_NOT_FOUND || slot_status == (u16)0) > > return -ENODEV; > > > > return !!(slot_status & PCI_EXP_SLTSTA_PDS); > > @@ -592,7 +592,7 @@ static irqreturn_t pciehp_isr(int irq, void *dev_id) > > > > read_status: > > pcie_capability_read_word(pdev, PCI_EXP_SLTSTA, &status); > > - if (status == (u16) ~0) { > > + if (status == (u16)0) { > > ctrl_info(ctrl, "%s: no response from device\n", __func__); > > if (parent) > > pm_runtime_put(parent); > > -- > > 2.18.2
diff --git a/drivers/pci/hotplug/pciehp_hpc.c b/drivers/pci/hotplug/pciehp_hpc.c index 53433b37e181..c1a67054948a 100644 --- a/drivers/pci/hotplug/pciehp_hpc.c +++ b/drivers/pci/hotplug/pciehp_hpc.c @@ -89,7 +89,7 @@ static int pcie_poll_cmd(struct controller *ctrl, int timeout) do { pcie_capability_read_word(pdev, PCI_EXP_SLTSTA, &slot_status); - if (slot_status == (u16) ~0) { + if (slot_status == (u16)0) { ctrl_info(ctrl, "%s: no response from device\n", __func__); return 0; @@ -165,7 +165,7 @@ static void pcie_do_write_cmd(struct controller *ctrl, u16 cmd, pcie_wait_cmd(ctrl); pcie_capability_read_word(pdev, PCI_EXP_SLTCTL, &slot_ctrl); - if (slot_ctrl == (u16) ~0) { + if (slot_ctrl == (u16)0) { ctrl_info(ctrl, "%s: no response from device\n", __func__); goto out; } @@ -236,7 +236,7 @@ int pciehp_check_link_active(struct controller *ctrl) int ret; ret = pcie_capability_read_word(pdev, PCI_EXP_LNKSTA, &lnk_status); - if (ret == PCIBIOS_DEVICE_NOT_FOUND || lnk_status == (u16)~0) + if (ret == PCIBIOS_DEVICE_NOT_FOUND || lnk_status == (u16)0) return -ENODEV; ret = !!(lnk_status & PCI_EXP_LNKSTA_DLLLA); @@ -440,7 +440,7 @@ int pciehp_card_present(struct controller *ctrl) int ret; ret = pcie_capability_read_word(pdev, PCI_EXP_SLTSTA, &slot_status); - if (ret == PCIBIOS_DEVICE_NOT_FOUND || slot_status == (u16)~0) + if (ret == PCIBIOS_DEVICE_NOT_FOUND || slot_status == (u16)0) return -ENODEV; return !!(slot_status & PCI_EXP_SLTSTA_PDS); @@ -592,7 +592,7 @@ static irqreturn_t pciehp_isr(int irq, void *dev_id) read_status: pcie_capability_read_word(pdev, PCI_EXP_SLTSTA, &status); - if (status == (u16) ~0) { + if (status == (u16)0) { ctrl_info(ctrl, "%s: no response from device\n", __func__); if (parent) pm_runtime_put(parent);