linux-kernel - [PATCH v7 1/4] PCI: Introduce pcim_alloc_irq

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Date:   Mon,  7 Jun 2021 23:39:13 +0800
From:   Dejin Zheng <zhengdejin5@...il.com>
To:     helgaas@...nel.org, corbet@....net, jarkko.nikula@...ux.intel.com,
        andriy.shevchenko@...ux.intel.com, mika.westerberg@...ux.intel.com,
        rric@...nel.org, bhelgaas@...gle.com, wsa@...nel.org,
        Sanket.Goswami@....com, linux-doc@...r.kernel.org,
        linux-i2c@...r.kernel.org, linux-pci@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, Dejin Zheng <zhengdejin5@...il.com>,
        kernel test robot <lkp@...el.com>
Subject: [PATCH v7 1/4] PCI: Introduce pcim_alloc_irq_vectors()

Introduce pcim_alloc_irq_vectors(), a device-managed version of
pci_alloc_irq_vectors(). Introducing this function can simplify
the error handling path in many drivers.

And use pci_free_irq_vectors() to replace some code in pcim_release(),
they are equivalent, and no functional change. It is more explicit
that pcim_alloc_irq_vectors() is a device-managed function.

When CONFIG_PCI=n, there is no stub for pci_is_managed(), but
pcim_alloc_irq_vectors() will use it, so add one like other similar stubs.
Otherwise there can be build errors, as here by kernel test robot
reported:
include/linux/pci.h: In function 'pcim_alloc_irq_vectors':
>> include/linux/pci.h:1847:7: error: implicit declaration of function 'pci_is_managed' [-Werror=implicit-function-declaration]
    1847 |  if (!pci_is_managed(dev))
         |       ^~~~~~~~~~~~~~

Reported-by: kernel test robot <lkp@...el.com>
Suggested-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Reviewed-by: Robert Richter <rric@...nel.org>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Acked-by: Bjorn Helgaas <bhelgaas@...gle.com>
Signed-off-by: Dejin Zheng <zhengdejin5@...il.com>
---
v6 -> v7:
	- rebase to PCI next branch
	- add a stub for pci_is_managed() when disable PCI for
	  fix build error in sparc architecture.
v5 -> v6:
	- rebase to 5.13-rc4
v4 -> v5:
	- Remove the check of enable device in pcim_alloc_irq_vectors()
	  and make it as a static line function.
v3 -> v4:
	- No change
v2 -> v3:
	- Add some commit comments for replace some codes in
	  pcim_release() by pci_free_irq_vectors().
v1 -> v2:
	- Use pci_free_irq_vectors() to replace some code in
	  pcim_release().
	- Modify some commit messages.

 drivers/pci/pci.c   |  5 +----
 include/linux/pci.h | 25 +++++++++++++++++++++++++
 2 files changed, 26 insertions(+), 4 deletions(-)

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 452351025a09..e3b3fc59bd35 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -1989,10 +1989,7 @@ static void pcim_release(struct device *gendev, void *res)
 	struct pci_devres *this = res;
 	int i;
 
-	if (dev->msi_enabled)
-		pci_disable_msi(dev);
-	if (dev->msix_enabled)
-		pci_disable_msix(dev);
+	pci_free_irq_vectors(dev);
 
 	for (i = 0; i < DEVICE_COUNT_RESOURCE; i++)
 		if (this->region_mask & (1 << i))
diff --git a/include/linux/pci.h b/include/linux/pci.h
index c20211e59a57..5783262c4643 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -1730,6 +1730,7 @@ static inline struct pci_dev *pci_get_class(unsigned int class,
 
 static inline void pci_set_master(struct pci_dev *dev) { }
 static inline int pci_enable_device(struct pci_dev *dev) { return -EIO; }
+static inline int pci_is_managed(struct pci_dev *pdev) { return 0; }
 static inline void pci_disable_device(struct pci_dev *dev) { }
 static inline int pcim_enable_device(struct pci_dev *pdev) { return -EIO; }
 static inline int pci_assign_resource(struct pci_dev *dev, int i)
@@ -1825,6 +1826,30 @@ pci_alloc_irq_vectors(struct pci_dev *dev, unsigned int min_vecs,
 					      NULL);
 }
 
+/**
+ * pcim_alloc_irq_vectors - a device-managed pci_alloc_irq_vectors()
+ * @dev:		PCI device to operate on
+ * @min_vecs:		minimum number of vectors required (must be >= 1)
+ * @max_vecs:		maximum (desired) number of vectors
+ * @flags:		flags or quirks for the allocation
+ *
+ * Return the number of vectors allocated, (which might be smaller than
+ * @max_vecs) if successful, or a negative error code on error. If less
+ * than @min_vecs interrupt vectors are available for @dev the function
+ * will fail with -ENOSPC.
+ *
+ * It depends on calling pcim_enable_device() to make IRQ resources
+ * manageable.
+ */
+static inline int
+pcim_alloc_irq_vectors(struct pci_dev *dev, unsigned int min_vecs,
+			unsigned int max_vecs, unsigned int flags)
+{
+	if (!pci_is_managed(dev))
+		return -EINVAL;
+	return pci_alloc_irq_vectors(dev, min_vecs, max_vecs, flags);
+}
+
 /* Include architecture-dependent settings and functions */
 
 #include <asm/pci.h>
-- 
2.30.1