Re: [PATCH] PCI: Reset failed bridge resources in PCI realloc

[Yinghai Lu <yinghai@kernel.org>]

[-- Attachment #1: Type: text/plain, Size: 2178 bytes --]

On Wed, Jul 30, 2014 at 1:00 AM, Guo Chao <yan@linux.vnet.ibm.com> wrote:
>         * However, in pbus_size_mem() we call calculate_memsize() to
>           calculate the final size. calculate_memsize() never shrinks
>           window, i.e. if old size is larger than newly sized result,
>           old size will be honored. Unfortunately, the old size at this
>           time is the sum of both normal BARs and SR-IOV BARs when doing
>           realloc.
>

that checking about old_size is added by:

| commit d65245c3297ac63abc51a976d92f45f2195d2854
| Author: Yinghai Lu <yinghai@kernel.org>
| Date:   Fri Jan 22 01:02:23 2010 -0800
|
|    PCI: don't shrink bridge resources
|
|    When clearing leaf bridge resources, trying to get a big enough one, we
|    could shrink the bridge if there is no resource under it.  Confirm
|    against the old resource side to make sure we're increasing the
|    allocation.

so to make both cases ok, may need to check if there is any children devices
on the dev->subordinate. Please check attached.

Thanks

Yinghai


---
 drivers/pci/setup-bus.c |   10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

Index: linux-2.6/drivers/pci/setup-bus.c
===================================================================
--- linux-2.6.orig/drivers/pci/setup-bus.c
+++ linux-2.6/drivers/pci/setup-bus.c
@@ -1622,8 +1622,11 @@ again:
         res->start = fail_res->start;
         res->end = fail_res->end;
         res->flags = fail_res->flags;
-        if (fail_res->dev->subordinate)
+        if (fail_res->dev->subordinate) {
             res->flags = 0;
+            if (!list_empty(&fail_res->dev->subordinate->devices))
+                res->start = res->end = 0;
+        }
     }
     free_list(&fail_head);

@@ -1688,8 +1691,11 @@ again:
         res->start = fail_res->start;
         res->end = fail_res->end;
         res->flags = fail_res->flags;
-        if (fail_res->dev->subordinate)
+        if (fail_res->dev->subordinate) {
             res->flags = 0;
+            if (!list_empty(&fail_res->dev->subordinate->devices))
+                res->start = res->end = 0;
+        }
     }
     free_list(&fail_head);

[-- Attachment #2: shrink_realloc_bridge_resource.patch --]
[-- Type: text/x-patch, Size: 975 bytes --]

---
 drivers/pci/setup-bus.c |   10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

Index: linux-2.6/drivers/pci/setup-bus.c
===================================================================
--- linux-2.6.orig/drivers/pci/setup-bus.c
+++ linux-2.6/drivers/pci/setup-bus.c
@@ -1622,8 +1622,11 @@ again:
 		res->start = fail_res->start;
 		res->end = fail_res->end;
 		res->flags = fail_res->flags;
-		if (fail_res->dev->subordinate)
+		if (fail_res->dev->subordinate) {
 			res->flags = 0;
+			if (!list_empty(&fail_res->dev->subordinate->devices))
+				res->start = res->end = 0;
+		}
 	}
 	free_list(&fail_head);
 
@@ -1688,8 +1691,11 @@ again:
 		res->start = fail_res->start;
 		res->end = fail_res->end;
 		res->flags = fail_res->flags;
-		if (fail_res->dev->subordinate)
+		if (fail_res->dev->subordinate) {
 			res->flags = 0;
+			if (!list_empty(&fail_res->dev->subordinate->devices))
+				res->start = res->end = 0;
+		}
 	}
 	free_list(&fail_head);