Re: [PATCH 0/8 v2] PCI: Align return values of PCIe capability and PCI accessors

[Bjorn Helgaas <helgaas@kernel.org>]

On Mon, Jun 15, 2020 at 09:32:17AM +0200, refactormyself@gmail.com wrote:
> From: Bolarinwa Olayemi Saheed <refactormyself@gmail.com>
> 
> 
> PATCH 1/8 to 7/8:
> PCIBIOS_ error codes have positive values and they are passed down the
> call heirarchy from accessors. For functions which are meant to return
> only a negative value on failure, passing on this value is a bug.
> To mitigate this, call pcibios_err_to_errno() before passing on return
> value from PCIe capability accessors call heirarchy. This function
> converts any positive PCIBIOS_ error codes to negative generic error
> values.
> 
> PATCH 8/8:
> The PCIe capability accessors can return 0, -EINVAL, or any PCIBIOS_ error
> code. The pci accessor on the other hand can only return 0 or any PCIBIOS_
> error code.This inconsistency among these accessor makes it harder for
> callers to check for errors.
> Return PCIBIOS_BAD_REGISTER_NUMBER instead of -EINVAL in all PCIe
> capability accessors.
> 
> MERGING:
> These may all be merged via the PCI tree, since it is a collection of
> similar fixes. This way they all get merged at once.
> 
> Version 2:
> * cc to maintainers and mailing lists
> * Edit the Subject to conform with previous style
> * reorder "Signed by" and "Suggested by"
> * made spelling corrections
> * fixed redundant initialisation in PATCH 3/8
> * include missing call to pcibios_err_to_errno() in PATCH 6/8 and 7/8
> 
> 
> Bolarinwa Olayemi Saheed (8):
>   dmaengine: ioatdma: Convert PCIBIOS_* errors to generic -E* errors
>   IB/hfi1: Convert PCIBIOS_* errors to generic -E* errors
>   IB/hfi1: Convert PCIBIOS_* errors to generic -E* errors
>   PCI: Convert PCIBIOS_* errors to generic -E* errors
>   scsi: smartpqi: Convert PCIBIOS_* errors to generic -E* errors
>   PCI/AER: Convert PCIBIOS_* errors to generic -E* errors
>   PCI/AER: Convert PCIBIOS_* errors to generic -E* errors
>   PCI: Align return values of PCIe capability and PCI accessorss
> 
>  drivers/dma/ioat/init.c               |  4 ++--
>  drivers/infiniband/hw/hfi1/pcie.c     | 18 +++++++++++++-----
>  drivers/pci/access.c                  |  8 ++++----
>  drivers/pci/pci.c                     | 10 ++++++++--
>  drivers/pci/pcie/aer.c                | 12 ++++++++++--
>  drivers/scsi/smartpqi/smartpqi_init.c |  6 +++++-
>  6 files changed, 42 insertions(+), 16 deletions(-)

Since these are really fixing a single PCI API problem, not individual
driver-related problems, I squashed the pcibios_err_to_errno() patches
together (except IB/hfi1, since Jason will take those separately) and
applied them to pci/misc, thanks!

The squashed patch as applied is:

commit d20df83b66cc ("PCI: Convert PCIe capability PCIBIOS errors to errno")
Author: Bolarinwa Olayemi Saheed <refactormyself@gmail.com>
Date:   Mon Jun 15 09:32:18 2020 +0200

    PCI: Convert PCIe capability PCIBIOS errors to errno
    
    The PCI config accessors (pci_read_config_word(), et al) return
    PCIBIOS_SUCCESSFUL (zero) or positive error values like
    PCIBIOS_FUNC_NOT_SUPPORTED.
    
    The PCIe capability accessors (pcie_capability_read_word(), et al)
    similarly return PCIBIOS errors, but some callers assume they return
    generic errno values like -EINVAL.
    
    For example, the Myri-10G probe function returns a positive PCIBIOS error
    if the pcie_capability_clear_and_set_word() in pcie_set_readrq() fails:
    
      myri10ge_probe
        status = pcie_set_readrq
          return pcie_capability_clear_and_set_word
        if (status)
          return status
    
    A positive return from a PCI driver probe function would cause a "Driver
    probe function unexpectedly returned" warning from local_pci_probe()
    instead of the desired probe failure.
    
    Convert PCIBIOS errors to generic errno for all callers of:
    
      pcie_capability_read_word
      pcie_capability_read_dword
      pcie_capability_write_word
      pcie_capability_write_dword
      pcie_capability_set_word
      pcie_capability_set_dword
      pcie_capability_clear_word
      pcie_capability_clear_dword
      pcie_capability_clear_and_set_word
      pcie_capability_clear_and_set_dword
    
    that check the return code for anything other than zero.
    
    [bhelgaas: commit log, squash together]
    Suggested-by: Bjorn Helgaas <bjorn@helgaas.com>
    Link: https://lore.kernel.org/r/20200615073225.24061-1-refactormyself@gmail.com
    Signed-off-by: Bolarinwa Olayemi Saheed <refactormyself@gmail.com>
    Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

diff --git a/drivers/dma/ioat/init.c b/drivers/dma/ioat/init.c
index 58d13564f88b..9a6a9ec3cf48 100644
--- a/drivers/dma/ioat/init.c
+++ b/drivers/dma/ioat/init.c
@@ -1195,13 +1195,13 @@ static int ioat3_dma_probe(struct ioatdma_device *ioat_dma, int dca)
 	/* disable relaxed ordering */
 	err = pcie_capability_read_word(pdev, IOAT_DEVCTRL_OFFSET, &val16);
 	if (err)
-		return err;
+		return pcibios_err_to_errno(err);
 
 	/* clear relaxed ordering enable */
 	val16 &= ~IOAT_DEVCTRL_ROE;
 	err = pcie_capability_write_word(pdev, IOAT_DEVCTRL_OFFSET, val16);
 	if (err)
-		return err;
+		return pcibios_err_to_errno(err);
 
 	if (ioat_dma->cap & IOAT_CAP_DPS)
 		writeb(ioat_pending_level + 1,
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index ce096272f52b..45c51aff9c03 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -5688,6 +5688,7 @@ EXPORT_SYMBOL(pcie_get_readrq);
 int pcie_set_readrq(struct pci_dev *dev, int rq)
 {
 	u16 v;
+	int ret;
 
 	if (rq < 128 || rq > 4096 || !is_power_of_2(rq))
 		return -EINVAL;
@@ -5706,8 +5707,10 @@ int pcie_set_readrq(struct pci_dev *dev, int rq)
 
 	v = (ffs(rq) - 8) << 12;
 
-	return pcie_capability_clear_and_set_word(dev, PCI_EXP_DEVCTL,
+	ret = pcie_capability_clear_and_set_word(dev, PCI_EXP_DEVCTL,
 						  PCI_EXP_DEVCTL_READRQ, v);
+
+	return pcibios_err_to_errno(ret);
 }
 EXPORT_SYMBOL(pcie_set_readrq);
 
@@ -5738,6 +5741,7 @@ EXPORT_SYMBOL(pcie_get_mps);
 int pcie_set_mps(struct pci_dev *dev, int mps)
 {
 	u16 v;
+	int ret;
 
 	if (mps < 128 || mps > 4096 || !is_power_of_2(mps))
 		return -EINVAL;
@@ -5747,8 +5751,10 @@ int pcie_set_mps(struct pci_dev *dev, int mps)
 		return -EINVAL;
 	v <<= 5;
 
-	return pcie_capability_clear_and_set_word(dev, PCI_EXP_DEVCTL,
+	ret = pcie_capability_clear_and_set_word(dev, PCI_EXP_DEVCTL,
 						  PCI_EXP_DEVCTL_PAYLOAD, v);
+
+	return pcibios_err_to_errno(ret);
 }
 EXPORT_SYMBOL(pcie_set_mps);
 
diff --git a/drivers/pci/pcie/aer.c b/drivers/pci/pcie/aer.c
index 3acf56683915..2dbc1fd2910b 100644
--- a/drivers/pci/pcie/aer.c
+++ b/drivers/pci/pcie/aer.c
@@ -224,20 +224,25 @@ int pcie_aer_is_native(struct pci_dev *dev)
 
 int pci_enable_pcie_error_reporting(struct pci_dev *dev)
 {
+	int rc;
+
 	if (!pcie_aer_is_native(dev))
 		return -EIO;
 
-	return pcie_capability_set_word(dev, PCI_EXP_DEVCTL, PCI_EXP_AER_FLAGS);
+	rc = pcie_capability_set_word(dev, PCI_EXP_DEVCTL, PCI_EXP_AER_FLAGS);
+	return pcibios_err_to_errno(rc);
 }
 EXPORT_SYMBOL_GPL(pci_enable_pcie_error_reporting);
 
 int pci_disable_pcie_error_reporting(struct pci_dev *dev)
 {
+	int rc;
+
 	if (!pcie_aer_is_native(dev))
 		return -EIO;
 
-	return pcie_capability_clear_word(dev, PCI_EXP_DEVCTL,
-					  PCI_EXP_AER_FLAGS);
+	rc = pcie_capability_clear_word(dev, PCI_EXP_DEVCTL, PCI_EXP_AER_FLAGS);
+	return pcibios_err_to_errno(rc);
 }
 EXPORT_SYMBOL_GPL(pci_disable_pcie_error_reporting);
 
diff --git a/drivers/scsi/smartpqi/smartpqi_init.c b/drivers/scsi/smartpqi/smartpqi_init.c
index cd157f11eb22..bd38c8cea56e 100644
--- a/drivers/scsi/smartpqi/smartpqi_init.c
+++ b/drivers/scsi/smartpqi/smartpqi_init.c
@@ -7423,8 +7423,12 @@ static int pqi_ctrl_init_resume(struct pqi_ctrl_info *ctrl_info)
 static inline int pqi_set_pcie_completion_timeout(struct pci_dev *pci_dev,
 	u16 timeout)
 {
-	return pcie_capability_clear_and_set_word(pci_dev, PCI_EXP_DEVCTL2,
+	int rc;
+
+	rc = pcie_capability_clear_and_set_word(pci_dev, PCI_EXP_DEVCTL2,
 		PCI_EXP_DEVCTL2_COMP_TIMEOUT, timeout);
+
+	return pcibios_err_to_errno(rc);
 }
 
 static int pqi_pci_init(struct pqi_ctrl_info *ctrl_info)