[PATCH v5 04/10] PCI: Make devres region requests consistent

Philipp Stanner
2024-04-03T08:07:35Z

Now that pure managed region request functions are available, the
implementation of the hybrid-functions which are only sometimes managed
can be made more consistent and readable by wrapping those
always-managed functions.

Implement a new pcim_ function for exclusively requested regions.
Have the pci_request / release functions call their pcim_ counterparts.
Remove the now surplus region_mask from struct pci_devres.

Signed-off-by: Philipp Stanner <pstanner@redhat.com>
---
drivers/pci/devres.c | 49 ++++++++++++++++++++++---------------------
drivers/pci/pci.c | 50 +++++++++++++++-----------------------------
drivers/pci/pci.h | 6 ------
include/linux/pci.h | 1 +
4 files changed, 43 insertions(+), 63 deletions(-)

diff --git a/drivers/pci/devres.c b/drivers/pci/devres.c
index bc31e3a8cc04..03662760d629 100644
--- a/drivers/pci/devres.c
+++ b/drivers/pci/devres.c
@@ -22,18 +22,15 @@
* _sometimes_ managed (e.g. pci_request_region()).
* 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().
+ * Users utilizing 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 1:
+ * 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.
*/

/*
@@ -399,21 +396,6 @@ 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 (this->region_mask & (1 << i))
- pci_release_region(dev, i);

if (this->mwi)
pci_clear_mwi(dev);
@@ -966,6 +948,25 @@ int pcim_request_region(struct pci_dev *pdev, int bar, const char *name)
}
EXPORT_SYMBOL(pcim_request_region);

+/**
+ * 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);
+}
+EXPORT_SYMBOL(pcim_request_region_exclusive);
+
/**
* pcim_release_region - Release a PCI BAR
* @pdev: PCI device to operate on
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 9d9d09534efe..c0c1ee17a06b 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -3869,7 +3869,15 @@ 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;
@@ -3879,20 +3887,6 @@ 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);

@@ -3920,14 +3914,18 @@ EXPORT_SYMBOL(pci_release_region);
* NOTE:
* This is a "hybrid" function: Its normally unmanaged, but becomes managed
* when pcim_enable_device() has been called in advance.
- * This hybrid feature is DEPRECATED! If you need to implement a new pci
- * function that does automatic cleanup, write a new pcim_* function that uses
- * devres directly.
+ * This hybrid feature is DEPRECATED! If you want managed cleanup, use the
+ * pcim_* functions instead.
*/
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;
@@ -3943,20 +3941,6 @@ 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 171884aba8e1..040ed2825554 100644
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -828,12 +828,6 @@ 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);
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 5782ad034178..0f203338f820 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -2330,6 +2330,7 @@ int pcim_iomap_regions_request_all(struct pci_dev *pdev, int mask,
const char *name);
void pcim_iounmap_regions(struct pci_dev *pdev, int mask);
int pcim_request_region(struct pci_dev *pdev, int bar, const char *res_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);
void pcim_release_all_regions(struct pci_dev *pdev);
int pcim_request_all_regions(struct pci_dev *pdev, const char *name);
--
2.44.0