PCI: Export pci_intx_unmanaged() and pcim_intx()

pci_intx() is a hybrid function which sometimes performs devres operations,
depending on whether pcim_enable_device() has been used to enable the
pci_dev. This sometimes-managed nature of the function is problematic.
Notably, it causes the function to allocate under some circumstances which
makes it unusable from interrupt context.

Export pcim_intx() (which is always managed) and rename __pcim_intx()
(which is never managed) to pci_intx_unmanaged() and export it as well.

Then all callers of pci_intx() can be ported to the version they need,
depending whether they use pci_enable_device() or pcim_enable_device().

Link: https://lore.kernel.org/r/20241209130632.132074-3-pstanner@redhat.com
Signed-off-by: Philipp Stanner <pstanner@redhat.com>
[bhelgaas: commit log]
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>

Author: Philipp Stanner

drivers/pci/devres.c

@@ -411,31 +411,12 @@ static inline bool mask_contains_bar(int mask, int bar)
 	return mask & BIT(bar);
 }
 
-/*
- * This is a copy of pci_intx() used to bypass the problem of recursive
- * function calls due to the hybrid nature of pci_intx().
- */
-static void __pcim_intx(struct pci_dev *pdev, int enable)
-{
-	u16 pci_command, new;
-
-	pci_read_config_word(pdev, PCI_COMMAND, &pci_command);
-
-	if (enable)
-		new = pci_command & ~PCI_COMMAND_INTX_DISABLE;
-	else
-		new = pci_command | PCI_COMMAND_INTX_DISABLE;
-
-	if (new != pci_command)
-		pci_write_config_word(pdev, PCI_COMMAND, new);
-}
-
 static void pcim_intx_restore(struct device *dev, void *data)
 {
 	struct pci_dev *pdev = to_pci_dev(dev);
 	struct pcim_intx_devres *res = data;
 
-	__pcim_intx(pdev, res->orig_intx);
+	pci_intx_unmanaged(pdev, res->orig_intx);
 }
 
 static struct pcim_intx_devres *get_or_create_intx_devres(struct device *dev)
@@ -472,10 +453,11 @@ int pcim_intx(struct pci_dev *pdev, int enable)
 		return -ENOMEM;
 
 	res->orig_intx = !enable;
-	__pcim_intx(pdev, enable);
+	pci_intx_unmanaged(pdev, enable);
 
 	return 0;
 }
+EXPORT_SYMBOL_GPL(pcim_intx);
 
 static void pcim_disable_device(void *pdev_raw)
 {

drivers/pci/pci.c

@@ -4479,6 +4479,35 @@ void pci_disable_parity(struct pci_dev *dev)
 	}
 }
 
+/**
+ * pci_intx_unmanaged - enables/disables PCI INTx for device dev,
+ * unmanaged version
+ * @pdev: the PCI device to operate on
+ * @enable: boolean: whether to enable or disable PCI INTx
+ *
+ * Enables/disables PCI INTx for device @pdev
+ *
+ * This function behavios identically to pci_intx(), but is never managed with
+ * devres.
+ */
+void pci_intx_unmanaged(struct pci_dev *pdev, int enable)
+{
+	u16 pci_command, new;
+
+	pci_read_config_word(pdev, PCI_COMMAND, &pci_command);
+
+	if (enable)
+		new = pci_command & ~PCI_COMMAND_INTX_DISABLE;
+	else
+		new = pci_command | PCI_COMMAND_INTX_DISABLE;
+
+	if (new == pci_command)
+		return;
+
+	pci_write_config_word(pdev, PCI_COMMAND, new);
+}
+EXPORT_SYMBOL_GPL(pci_intx_unmanaged);
+
 /**
  * pci_intx - enables/disables PCI INTx for device dev
  * @pdev: the PCI device to operate on

include/linux/pci.h

@@ -1350,6 +1350,7 @@ int __must_check pcim_set_mwi(struct pci_dev *dev);
 int pci_try_set_mwi(struct pci_dev *dev);
 void pci_clear_mwi(struct pci_dev *dev);
 void pci_disable_parity(struct pci_dev *dev);
+void pci_intx_unmanaged(struct pci_dev *pdev, int enable);
 void pci_intx(struct pci_dev *dev, int enable);
 bool pci_check_and_mask_intx(struct pci_dev *dev);
 bool pci_check_and_unmask_intx(struct pci_dev *dev);
@@ -2297,6 +2298,7 @@ static inline void pci_fixup_device(enum pci_fixup_pass pass,
 				    struct pci_dev *dev) { }
 #endif
 
+int pcim_intx(struct pci_dev *pdev, int enabled);
 int pcim_request_all_regions(struct pci_dev *pdev, const char *name);
 void __iomem *pcim_iomap(struct pci_dev *pdev, int bar, unsigned long maxlen);
 void __iomem *pcim_iomap_region(struct pci_dev *pdev, int bar,