Re: [PATCH v5 1/7] PCI/ATS: Fix pci_prg_resp_pasid_required() dependency issues

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On 8/12/19 1:04 PM, Bjorn Helgaas wrote:
On Thu, Aug 01, 2019 at 05:05:58PM -0700, sathyanarayanan.kuppuswamy@xxxxxxxxxxxxxxx wrote:
From: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@xxxxxxxxxxxxxxx>

Since pci_prg_resp_pasid_required() function has dependency on both
PASID and PRI, define it only if both CONFIG_PCI_PRI and
CONFIG_PCI_PASID config options are enabled.
I don't really like this.  It makes the #ifdefs more complicated and I
don't think it really buys us anything.  Will anything break if we
just drop this patch?
Yes, this function uses "pri_lock" mutex which is only defined if CONFIG_PCI_PRI is enabled. So not protecting this function within CONFIG_PCI_PRI will lead to compilation issues.

Fixes: e5567f5f6762 ("PCI/ATS: Add pci_prg_resp_pasid_required()
interface.")
Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@xxxxxxxxxxxxxxx>
---
  drivers/pci/ats.c       | 10 ++++++----
  include/linux/pci-ats.h | 12 +++++++++---
  2 files changed, 15 insertions(+), 7 deletions(-)

diff --git a/drivers/pci/ats.c b/drivers/pci/ats.c
index e18499243f84..cdd936d10f68 100644
--- a/drivers/pci/ats.c
+++ b/drivers/pci/ats.c
@@ -395,6 +395,8 @@ int pci_pasid_features(struct pci_dev *pdev)
  }
  EXPORT_SYMBOL_GPL(pci_pasid_features);
+#ifdef CONFIG_PCI_PRI
+
  /**
   * pci_prg_resp_pasid_required - Return PRG Response PASID Required bit
   *				 status.
@@ -402,10 +404,8 @@ EXPORT_SYMBOL_GPL(pci_pasid_features);
   *
   * Returns 1 if PASID is required in PRG Response Message, 0 otherwise.
   *
- * Even though the PRG response PASID status is read from PRI Status
- * Register, since this API will mainly be used by PASID users, this
- * function is defined within #ifdef CONFIG_PCI_PASID instead of
- * CONFIG_PCI_PRI.
+ * Since this API has dependency on both PRI and PASID, protect it
+ * with both CONFIG_PCI_PRI and CONFIG_PCI_PASID.
   */
  int pci_prg_resp_pasid_required(struct pci_dev *pdev)
  {
@@ -425,6 +425,8 @@ int pci_prg_resp_pasid_required(struct pci_dev *pdev)
  }
  EXPORT_SYMBOL_GPL(pci_prg_resp_pasid_required);
+#endif
+
  #define PASID_NUMBER_SHIFT	8
  #define PASID_NUMBER_MASK	(0x1f << PASID_NUMBER_SHIFT)
  /**
diff --git a/include/linux/pci-ats.h b/include/linux/pci-ats.h
index 1ebb88e7c184..1a0bdaee2f32 100644
--- a/include/linux/pci-ats.h
+++ b/include/linux/pci-ats.h
@@ -40,7 +40,6 @@ void pci_disable_pasid(struct pci_dev *pdev);
  void pci_restore_pasid_state(struct pci_dev *pdev);
  int pci_pasid_features(struct pci_dev *pdev);
  int pci_max_pasids(struct pci_dev *pdev);
-int pci_prg_resp_pasid_required(struct pci_dev *pdev);
#else /* CONFIG_PCI_PASID */ @@ -67,11 +66,18 @@ static inline int pci_max_pasids(struct pci_dev *pdev)
  	return -EINVAL;
  }
+#endif /* CONFIG_PCI_PASID */
+
+#if defined(CONFIG_PCI_PRI) && defined(CONFIG_PCI_PASID)
+
+int pci_prg_resp_pasid_required(struct pci_dev *pdev);
+
+#else /* CONFIG_PCI_PASID && CONFIG_PCI_PRI */
+
  static inline int pci_prg_resp_pasid_required(struct pci_dev *pdev)
  {
  	return 0;
  }
-#endif /* CONFIG_PCI_PASID */
-
+#endif
#endif /* LINUX_PCI_ATS_H*/
--
2.21.0

--
Sathyanarayanan Kuppuswamy
Linux kernel developer




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