PCI: Add managed pcim_request_region()

These existing functions:

  pci_request_region()
  pci_request_selected_regions()
  pci_request_selected_regions_exclusive()

are "hybrid" functions built on __pci_request_region() and are managed if
pcim_enable_device() has been called, but unmanaged otherwise.

Add these new functions:

  pcim_request_region()
  pcim_request_region_exclusive()

These are *always* managed and use the new pcim_addr_devres tracking
infrastructure instead of find_pci_dr() and struct pci_devres.region_mask.

Implement the hybrid functions using the new "pure" functions and remove
struct pci_devres.region_mask, which is no longer needed.

Link: https://lore.kernel.org/r/20240613115032.29098-6-pstanner@redhat.com
Signed-off-by: Philipp Stanner <pstanner@redhat.com>
Signed-off-by: Krzysztof Wilczyński <kwilczynski@kernel.org>
[bhelgaas: commit log]
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

diff --git a/drivers/pci/devres.c b/drivers/pci/devres.c
index a5957b4cbc0e949b533889c8d77a66b058466898..e4c37fcb12df3187baa7951feac6e628afdc5faf 100644 (file)
--- a/drivers/pci/devres.c
+++ b/drivers/pci/devres.c
@@ -24,18 +24,16 @@
  *
  *    Consequently, in the new API, region requests performed by the pcim_
  *    functions are automatically cleaned up through the devres callback
- *    pcim_addr_resource_release(), while requests performed by
- *    pcim_enable_device() + pci_*region*() are automatically cleaned up
- *    through the for-loop in pcim_release().
+ *    pcim_addr_resource_release().
  *
- * TODO 1:
+ *    Users of pcim_enable_device() + pci_*region*() are redirected in
+ *    pci.c to the managed functions here in this file. This isn't exactly
+ *    perfect, but the only alternative way would be to port ALL drivers
+ *    using said combination to pcim_ functions.
+ *
+ * TODO:
  * Remove the legacy table entirely once all calls to pcim_iomap_table() in
  * the kernel have been removed.
- *
- * TODO 2:
- * Port everyone calling pcim_enable_device() + pci_*region*() to using the
- * pcim_ functions. Then, remove all devres functionality from pci_*region*()
- * functions and remove the associated cleanups described above in point #2.
  */
 
 /*
@@ -402,22 +400,6 @@ static void pcim_release(struct device *gendev, void *res)
 {
        struct pci_dev *dev = to_pci_dev(gendev);
        struct pci_devres *this = res;
-       int i;
-
-       /*
-        * This is legacy code.
-        *
-        * All regions requested by a pcim_ function do get released through
-        * pcim_addr_resource_release(). Thanks to the hybrid nature of the pci_
-        * region-request functions, this for-loop has to release the regions
-        * if they have been requested by such a function.
-        *
-        * TODO: Remove this once all users of pcim_enable_device() PLUS
-        * pci-region-request-functions have been ported to pcim_ functions.
-        */
-       for (i = 0; i < DEVICE_COUNT_RESOURCE; i++)
-               if (mask_contains_bar(this->region_mask, i))
-                       pci_release_region(dev, i);
 
        if (this->mwi)
                pci_clear_mwi(dev);
@@ -826,11 +808,29 @@ static int _pcim_request_region(struct pci_dev *pdev, int bar, const char *name,
  * The region will automatically be released on driver detach. If desired,
  * release manually only with pcim_release_region().
  */
-static int pcim_request_region(struct pci_dev *pdev, int bar, const char *name)
+int pcim_request_region(struct pci_dev *pdev, int bar, const char *name)
 {
        return _pcim_request_region(pdev, bar, name, 0);
 }
 
+/**
+ * pcim_request_region_exclusive - Request a PCI BAR exclusively
+ * @pdev: PCI device to requestion region for
+ * @bar: Index of BAR to request
+ * @name: Name associated with the request
+ *
+ * Returns: 0 on success, a negative error code on failure.
+ *
+ * Request region specified by @bar exclusively.
+ *
+ * The region will automatically be released on driver detach. If desired,
+ * release manually only with pcim_release_region().
+ */
+int pcim_request_region_exclusive(struct pci_dev *pdev, int bar, const char *name)
+{
+       return _pcim_request_region(pdev, bar, name, IORESOURCE_EXCLUSIVE);
+}
+
 /**
  * pcim_release_region - Release a PCI BAR
  * @pdev: PCI device to operate on
@@ -839,7 +839,7 @@ static int pcim_request_region(struct pci_dev *pdev, int bar, const char *name)
  * Release a region manually that was previously requested by
  * pcim_request_region().
  */
-static void pcim_release_region(struct pci_dev *pdev, int bar)
+void pcim_release_region(struct pci_dev *pdev, int bar)
 {
        struct pcim_addr_devres res_searched;
 

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index d94445f5f882e129c2f31543f25e670836896d07..7013699db242708fb3d71f556edeeab5e9372e6f 100644 (file)
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -3872,7 +3872,15 @@ EXPORT_SYMBOL(pci_enable_atomic_ops_to_root);
  */
 void pci_release_region(struct pci_dev *pdev, int bar)
 {
-       struct pci_devres *dr;
+       /*
+        * This is done for backwards compatibility, because the old PCI devres
+        * API had a mode in which the function became managed if it had been
+        * enabled with pcim_enable_device() instead of pci_enable_device().
+        */
+       if (pci_is_managed(pdev)) {
+               pcim_release_region(pdev, bar);
+               return;
+       }
 
        if (pci_resource_len(pdev, bar) == 0)
                return;
@@ -3882,21 +3890,6 @@ void pci_release_region(struct pci_dev *pdev, int bar)
        else if (pci_resource_flags(pdev, bar) & IORESOURCE_MEM)
                release_mem_region(pci_resource_start(pdev, bar),
                                pci_resource_len(pdev, bar));
-
-       /*
-        * This devres utility makes this function sometimes managed
-        * (when pcim_enable_device() has been called before).
-        *
-        * This is bad because it conflicts with the pcim_ functions being
-        * exclusively responsible for managed PCI. Its "sometimes yes,
-        * sometimes no" nature can cause bugs.
-        *
-        * TODO: Remove this once all users that use pcim_enable_device() PLUS
-        * a region request function have been ported to using pcim_ functions.
-        */
-       dr = find_pci_dr(pdev);
-       if (dr)
-               dr->region_mask &= ~(1 << bar);
 }
 EXPORT_SYMBOL(pci_release_region);
 
@@ -3922,7 +3915,12 @@ EXPORT_SYMBOL(pci_release_region);
 static int __pci_request_region(struct pci_dev *pdev, int bar,
                                const char *res_name, int exclusive)
 {
-       struct pci_devres *dr;
+       if (pci_is_managed(pdev)) {
+               if (exclusive == IORESOURCE_EXCLUSIVE)
+                       return pcim_request_region_exclusive(pdev, bar, res_name);
+
+               return pcim_request_region(pdev, bar, res_name);
+       }
 
        if (pci_resource_len(pdev, bar) == 0)
                return 0;
@@ -3938,21 +3936,6 @@ static int __pci_request_region(struct pci_dev *pdev, int bar,
                        goto err_out;
        }
 
-       /*
-        * This devres utility makes this function sometimes managed
-        * (when pcim_enable_device() has been called before).
-        *
-        * This is bad because it conflicts with the pcim_ functions being
-        * exclusively responsible for managed pci. Its "sometimes yes,
-        * sometimes no" nature can cause bugs.
-        *
-        * TODO: Remove this once all users that use pcim_enable_device() PLUS
-        * a region request function have been ported to using pcim_ functions.
-        */
-       dr = find_pci_dr(pdev);
-       if (dr)
-               dr->region_mask |= 1 << bar;
-
        return 0;
 
 err_out:

diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
index c09487f5550c9299a10a535b7be70218a243c96d..37894852c2a044f8c9bd41c0dbc8d10d8d864b04 100644 (file)
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -826,16 +826,15 @@ struct pci_devres {
        unsigned int orig_intx:1;
        unsigned int restore_intx:1;
        unsigned int mwi:1;
-
-       /*
-        * TODO: remove the region_mask once everyone calling
-        * pcim_enable_device() + pci_*region*() is ported to pcim_ functions.
-        */
-       u32 region_mask;
 };
 
 struct pci_devres *find_pci_dr(struct pci_dev *pdev);
 
+int pcim_request_region(struct pci_dev *pdev, int bar, const char *name);
+int pcim_request_region_exclusive(struct pci_dev *pdev, int bar,
+                                 const char *name);
+void pcim_release_region(struct pci_dev *pdev, int bar);
+
 /*
  * Config Address for PCI Configuration Mechanism #1
  *