Patchwork [1/2] PCI: Split pci_assign_unassigned_resources to per root bus

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Submitter Yinghai Lu
Date May 6, 2013, 11:15 p.m.
Message ID <1367882130-19452-1-git-send-email-yinghai@kernel.org>
Download mbox | patch
Permalink /patch/241827/
State Superseded
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Comments

Yinghai Lu - May 6, 2013, 11:15 p.m.
BenH reported that there is some assign unassigned resource problem
in powerpc.

It turns out after
| commit 0c5be0cb0edfe3b5c4b62eac68aa2aa15ec681af
| Date:   Thu Feb 23 19:23:29 2012 -0800
|
|    PCI: Retry on IORESOURCE_IO type allocations

even the root bus does not have io port range, it will keep retrying
to realloc with mmio.

Current retry logic is : try with must+optional at first, and if
it fails will try must then try to extend must with optional.
That will fail as mmio-non-pref and mmio-pref for bridge will
be next to each other. So we have no chance to extend mmio-non-pref.

We should not fall into retry in this case, as root bus does
not io port range.

Before we do that we need to split pci_assign_unassiged_resource
to every root bus, so we can stop early for root bus without ioport
range, and still continue to retry on buses that do have ioport range.

This will be become more often when we have x86 8 sockets or 32 sockets
system, and those system will have one root bus per socket.
They will have some root buses do not have ioport range.

For the retry failing, we could allocate mmio-non-pref bottom-up
and mmio-pref will be top-down, but that could not be material for v3.10.

Reported-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Yinghai Lu <yinghai@kernel.org>

---
 drivers/pci/setup-bus.c |  101 +++++++++++++++++++++++-------------------------
 1 file changed, 49 insertions(+), 52 deletions(-)

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Benjamin Herrenschmidt - May 7, 2013, 12:50 a.m.
On Mon, 2013-05-06 at 16:15 -0700, Yinghai Lu wrote:
> BenH reported that there is some assign unassigned resource problem
> in powerpc.
> 
> It turns out after
> | commit 0c5be0cb0edfe3b5c4b62eac68aa2aa15ec681af
> | Date:   Thu Feb 23 19:23:29 2012 -0800
> |
> |    PCI: Retry on IORESOURCE_IO type allocations
> 
> even the root bus does not have io port range, it will keep retrying
> to realloc with mmio.
> 
> Current retry logic is : try with must+optional at first, and if
> it fails will try must then try to extend must with optional.
> That will fail as mmio-non-pref and mmio-pref for bridge will
> be next to each other. So we have no chance to extend mmio-non-pref.

Shouldn't you do completely separate passes for IO and MMIO through the
whole lot instead since they are completely separate address spaces ?

IE. Even a legit setup with IOs, in case of failures on the IO side
(resource exhaustion, FW bugs, ...) we shouldn't retry the memory side
and vice-versa.

Note that I'm a bit worried by how invasive your proposed patch is. I
will let Gavin test it and if it works I'm happy but keep in mind that I
really need that fixed in 3.10 ... (especially since there are noises
around about a certain enterprise distro using that version...)

Cheers,
Ben.


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Yinghai Lu - May 7, 2013, 7:34 a.m.
On Mon, May 6, 2013 at 6:33 PM, Gavin Shan <shangw@linux.vnet.ibm.com> wrote:
>
> Run the kernel with Yinghai's code on the simulator and it's failed to
> enable PCI devices (including p2p bridges) as the attached kernel log
> indicates.

Please check attached v2 for second patch.

Thanks

Yinghai
Bjorn Helgaas - May 21, 2013, 8:41 p.m.
On Mon, May 06, 2013 at 04:15:29PM -0700, Yinghai Lu wrote:
> BenH reported that there is some assign unassigned resource problem
> in powerpc.
> 
> It turns out after
> | commit 0c5be0cb0edfe3b5c4b62eac68aa2aa15ec681af
> | Date:   Thu Feb 23 19:23:29 2012 -0800
> |
> |    PCI: Retry on IORESOURCE_IO type allocations
> 
> even the root bus does not have io port range, it will keep retrying
> to realloc with mmio.
> 
> Current retry logic is : try with must+optional at first, and if
> it fails will try must then try to extend must with optional.
> That will fail as mmio-non-pref and mmio-pref for bridge will
> be next to each other. So we have no chance to extend mmio-non-pref.
> 
> We should not fall into retry in this case, as root bus does
> not io port range.
> 
> Before we do that we need to split pci_assign_unassiged_resource
> to every root bus, so we can stop early for root bus without ioport
> range, and still continue to retry on buses that do have ioport range.
> 
> This will be become more often when we have x86 8 sockets or 32 sockets
> system, and those system will have one root bus per socket.
> They will have some root buses do not have ioport range.
> 
> For the retry failing, we could allocate mmio-non-pref bottom-up
> and mmio-pref will be top-down, but that could not be material for v3.10.

If I understand correctly, this particular patch makes no functional
changes, so the changelog above should be saved for the patches that *do*
actually fix problems.

> 
> Reported-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
> Signed-off-by: Yinghai Lu <yinghai@kernel.org>
> 
> ---
>  drivers/pci/setup-bus.c |  101 +++++++++++++++++++++++-------------------------
>  1 file changed, 49 insertions(+), 52 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
> @@ -1315,21 +1315,6 @@ static int __init pci_bus_get_depth(stru
>  
>  	return depth;
>  }
> -static int __init pci_get_max_depth(void)
> -{
> -	int depth = 0;
> -	struct pci_bus *bus;
> -
> -	list_for_each_entry(bus, &pci_root_buses, node) {
> -		int ret;
> -
> -		ret = pci_bus_get_depth(bus);
> -		if (ret > depth)
> -			depth = ret;
> -	}
> -
> -	return depth;
> -}
>  
>  /*
>   * -1: undefined, will auto detect later
> @@ -1354,34 +1339,41 @@ void __init pci_realloc_get_opt(char *st
>  	else if (!strncmp(str, "on", 2))
>  		pci_realloc_enable = user_enabled;
>  }
> -static bool __init pci_realloc_enabled(void)
> +static bool __init pci_realloc_enabled(enum enable_type enable)
>  {
> -	return pci_realloc_enable >= user_enabled;
> +	return enable >= user_enabled;
>  }
>  
> -static void __init pci_realloc_detect(void)
> +static enum enable_type __init pci_realloc_detect(struct pci_bus *bus,
> +			 enum enable_type enable_local)
>  {
>  #if defined(CONFIG_PCI_IOV) && defined(CONFIG_PCI_REALLOC_ENABLE_AUTO)
> -	struct pci_dev *dev = NULL;
> +	struct pci_dev *dev;
>  
> -	if (pci_realloc_enable != undefined)
> -		return;
> +	if (enable_local != undefined)
> +		return enable_local;
>  
> -	for_each_pci_dev(dev) {
> +	list_for_each_entry(dev, &bus->devices, bus_list) {
>  		int i;
>  
>  		for (i = PCI_IOV_RESOURCES; i <= PCI_IOV_RESOURCE_END; i++) {
>  			struct resource *r = &dev->resource[i];
>  
>  			/* Not assigned, or rejected by kernel ? */
> -			if (r->flags && !r->start) {
> -				pci_realloc_enable = auto_enabled;
> -
> -				return;
> -			}
> +			if (r->flags && !r->start)
> +				return auto_enabled;
>  		}
>  	}
> +
> +	list_for_each_entry(dev, &bus->devices, bus_list) {
> +		struct pci_bus *child = dev->subordinate;
> +
> +		if (child &&
> +		    pci_realloc_detect(child, enable_local) == auto_enabled)
> +			return auto_enabled;
> +	}

This uses recursion and basically does the same thing as pci_walk_bus().
I think it will be clearer if you make it look something like this:

        static int count_unassigned_resources(struct pci_dev *dev, void *data)
        {
          int *count = data;

          for (i = PCI_IOV_RESOURCES; ...)
            if (r->flags && !r->start)
              *count++;

          return 0;
        }

        static pci_realloc_detect(struct pci_bus *bus, ...  enable_local)
        {
	  int unassigned;

          if (enable_local != undefined)
            return enable_local;

	  unassigned = 0;
	  pci_walk_bus(bus, count_unassigned_resources, &unassigned);
	  if (unassigned)
	    return auto_enabled;

          return enable_local;
        }


>  #endif
> +	return enable_local;
>  }
>  
>  /*
> @@ -1389,10 +1381,9 @@ static void __init pci_realloc_detect(vo
>   * second  and later try will clear small leaf bridge res
>   * will stop till to the max  deepth if can not find good one
>   */
> -void __init
> -pci_assign_unassigned_resources(void)
> +static void __init
> +pci_assign_unassigned_root_bus_resources(struct pci_bus *bus)
>  {
> -	struct pci_bus *bus;
>  	LIST_HEAD(realloc_head); /* list of resources that
>  					want additional resources */
>  	struct list_head *add_list = NULL;
> @@ -1403,15 +1394,17 @@ pci_assign_unassigned_resources(void)
>  	unsigned long type_mask = IORESOURCE_IO | IORESOURCE_MEM |
>  				  IORESOURCE_PREFETCH;
>  	int pci_try_num = 1;
> +	enum enable_type enable_local;
>  
>  	/* don't realloc if asked to do so */
> -	pci_realloc_detect();
> -	if (pci_realloc_enabled()) {
> -		int max_depth = pci_get_max_depth();
> +	enable_local = pci_realloc_detect(bus, pci_realloc_enable);
> +	if (pci_realloc_enabled(enable_local)) {
> +		int max_depth = pci_bus_get_depth(bus);
>  
>  		pci_try_num = max_depth + 1;
> -		printk(KERN_DEBUG "PCI: max bus depth: %d pci_try_num: %d\n",
> -			 max_depth, pci_try_num);
> +		dev_printk(KERN_DEBUG, &bus->dev,
> +			   "max bus depth: %d pci_try_num: %d\n",
> +			   max_depth, pci_try_num);
>  	}
>  
>  again:
> @@ -1423,12 +1416,10 @@ again:
>  		add_list = &realloc_head;
>  	/* Depth first, calculate sizes and alignments of all
>  	   subordinate buses. */
> -	list_for_each_entry(bus, &pci_root_buses, node)
> -		__pci_bus_size_bridges(bus, add_list);
> +	__pci_bus_size_bridges(bus, add_list);
>  
>  	/* Depth last, allocate resources and update the hardware. */
> -	list_for_each_entry(bus, &pci_root_buses, node)
> -		__pci_bus_assign_resources(bus, add_list, &fail_head);
> +	__pci_bus_assign_resources(bus, add_list, &fail_head);
>  	if (add_list)
>  		BUG_ON(!list_empty(add_list));
>  	tried_times++;
> @@ -1438,17 +1429,17 @@ again:
>  		goto enable_and_dump;
>  
>  	if (tried_times >= pci_try_num) {
> -		if (pci_realloc_enable == undefined)
> -			printk(KERN_INFO "Some PCI device resources are unassigned, try booting with pci=realloc\n");
> -		else if (pci_realloc_enable == auto_enabled)
> -			printk(KERN_INFO "Automatically enabled pci realloc, if you have problem, try booting with pci=realloc=off\n");
> +		if (enable_local == undefined)
> +			dev_info(&bus->dev, "Some PCI device resources are unassigned, try booting with pci=realloc\n");
> +		else if (enable_local == auto_enabled)
> +			dev_info(&bus->dev, "Automatically enabled pci realloc, if you have problem, try booting with pci=realloc=off\n");

I think you can add enable_local and the pci_realloc_enabled() parameter
in a separate patch.  That will remove distractions from the main patch.

>  
>  		free_list(&fail_head);
>  		goto enable_and_dump;
>  	}
>  
> -	printk(KERN_DEBUG "PCI: No. %d try to assign unassigned res\n",
> -			 tried_times + 1);
> +	dev_printk(KERN_DEBUG, &bus->dev,
> +		   "No. %d try to assign unassigned res\n", tried_times + 1);
>  
>  	/* third times and later will not check if it is leaf */
>  	if ((tried_times + 1) > 2)
> @@ -1458,12 +1449,11 @@ again:
>  	 * Try to release leaf bridge's resources that doesn't fit resource of
>  	 * child device under that bridge
>  	 */
> -	list_for_each_entry(fail_res, &fail_head, list) {
> -		bus = fail_res->dev->bus;
> -		pci_bus_release_bridge_resources(bus,
> +	list_for_each_entry(fail_res, &fail_head, list)
> +		pci_bus_release_bridge_resources(fail_res->dev->bus,

This change is gratuitous and distracting.  Please move it to a
separate patch.

>  						 fail_res->flags & type_mask,
>  						 rel_type);
> -	}
> +
>  	/* restore size and flags */
>  	list_for_each_entry(fail_res, &fail_head, list) {
>  		struct resource *res = fail_res->res;
> @@ -1480,12 +1470,19 @@ again:
>  
>  enable_and_dump:
>  	/* Depth last, update the hardware. */
> -	list_for_each_entry(bus, &pci_root_buses, node)
> -		pci_enable_bridges(bus);
> +	pci_enable_bridges(bus);
>  
>  	/* dump the resource on buses */
> +	pci_bus_dump_resources(bus);
> +}
> +
> +void __init
> +pci_assign_unassigned_resources(void)
> +{
> +	struct pci_bus *bus;
> +
>  	list_for_each_entry(bus, &pci_root_buses, node)
> -		pci_bus_dump_resources(bus);
> +		pci_assign_unassigned_root_bus_resources(bus);
>  }
>  
>  void pci_assign_unassigned_bridge_resources(struct pci_dev *bridge)

I think this should be split up into something like the following patches
so we can see what's going on here:

    - Remove "bus" temporary when calling pci_bus_release_bridge_resources()

    - Add pci_realloc_enabled() parameter and enable_local

    - Add pci_realloc_detect() parameters.  The "bus" parameter is 
      ignored for now.

    - Change pci_realloc_detect() to iterate over pci_root_buses and
      call pci_walk_bus() to find any unassigned resources instead of
      using for_each_pci_dev().

    - Split pci_assign_unassigned_resources() into iterating over
      pci_root_buses and calling pci_assign_unassigned_root_bus_resources(bus).
      Change pci_realloc_detect() to only walk the supplied bus instead
      of everything in pci_root_buses.  This will be basically just removing
      list_for_each_entry(bus, &pci_root_buses, node) loops.

Bjorn
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Patch

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
@@ -1315,21 +1315,6 @@  static int __init pci_bus_get_depth(stru
 
 	return depth;
 }
-static int __init pci_get_max_depth(void)
-{
-	int depth = 0;
-	struct pci_bus *bus;
-
-	list_for_each_entry(bus, &pci_root_buses, node) {
-		int ret;
-
-		ret = pci_bus_get_depth(bus);
-		if (ret > depth)
-			depth = ret;
-	}
-
-	return depth;
-}
 
 /*
  * -1: undefined, will auto detect later
@@ -1354,34 +1339,41 @@  void __init pci_realloc_get_opt(char *st
 	else if (!strncmp(str, "on", 2))
 		pci_realloc_enable = user_enabled;
 }
-static bool __init pci_realloc_enabled(void)
+static bool __init pci_realloc_enabled(enum enable_type enable)
 {
-	return pci_realloc_enable >= user_enabled;
+	return enable >= user_enabled;
 }
 
-static void __init pci_realloc_detect(void)
+static enum enable_type __init pci_realloc_detect(struct pci_bus *bus,
+			 enum enable_type enable_local)
 {
 #if defined(CONFIG_PCI_IOV) && defined(CONFIG_PCI_REALLOC_ENABLE_AUTO)
-	struct pci_dev *dev = NULL;
+	struct pci_dev *dev;
 
-	if (pci_realloc_enable != undefined)
-		return;
+	if (enable_local != undefined)
+		return enable_local;
 
-	for_each_pci_dev(dev) {
+	list_for_each_entry(dev, &bus->devices, bus_list) {
 		int i;
 
 		for (i = PCI_IOV_RESOURCES; i <= PCI_IOV_RESOURCE_END; i++) {
 			struct resource *r = &dev->resource[i];
 
 			/* Not assigned, or rejected by kernel ? */
-			if (r->flags && !r->start) {
-				pci_realloc_enable = auto_enabled;
-
-				return;
-			}
+			if (r->flags && !r->start)
+				return auto_enabled;
 		}
 	}
+
+	list_for_each_entry(dev, &bus->devices, bus_list) {
+		struct pci_bus *child = dev->subordinate;
+
+		if (child &&
+		    pci_realloc_detect(child, enable_local) == auto_enabled)
+			return auto_enabled;
+	}
 #endif
+	return enable_local;
 }
 
 /*
@@ -1389,10 +1381,9 @@  static void __init pci_realloc_detect(vo
  * second  and later try will clear small leaf bridge res
  * will stop till to the max  deepth if can not find good one
  */
-void __init
-pci_assign_unassigned_resources(void)
+static void __init
+pci_assign_unassigned_root_bus_resources(struct pci_bus *bus)
 {
-	struct pci_bus *bus;
 	LIST_HEAD(realloc_head); /* list of resources that
 					want additional resources */
 	struct list_head *add_list = NULL;
@@ -1403,15 +1394,17 @@  pci_assign_unassigned_resources(void)
 	unsigned long type_mask = IORESOURCE_IO | IORESOURCE_MEM |
 				  IORESOURCE_PREFETCH;
 	int pci_try_num = 1;
+	enum enable_type enable_local;
 
 	/* don't realloc if asked to do so */
-	pci_realloc_detect();
-	if (pci_realloc_enabled()) {
-		int max_depth = pci_get_max_depth();
+	enable_local = pci_realloc_detect(bus, pci_realloc_enable);
+	if (pci_realloc_enabled(enable_local)) {
+		int max_depth = pci_bus_get_depth(bus);
 
 		pci_try_num = max_depth + 1;
-		printk(KERN_DEBUG "PCI: max bus depth: %d pci_try_num: %d\n",
-			 max_depth, pci_try_num);
+		dev_printk(KERN_DEBUG, &bus->dev,
+			   "max bus depth: %d pci_try_num: %d\n",
+			   max_depth, pci_try_num);
 	}
 
 again:
@@ -1423,12 +1416,10 @@  again:
 		add_list = &realloc_head;
 	/* Depth first, calculate sizes and alignments of all
 	   subordinate buses. */
-	list_for_each_entry(bus, &pci_root_buses, node)
-		__pci_bus_size_bridges(bus, add_list);
+	__pci_bus_size_bridges(bus, add_list);
 
 	/* Depth last, allocate resources and update the hardware. */
-	list_for_each_entry(bus, &pci_root_buses, node)
-		__pci_bus_assign_resources(bus, add_list, &fail_head);
+	__pci_bus_assign_resources(bus, add_list, &fail_head);
 	if (add_list)
 		BUG_ON(!list_empty(add_list));
 	tried_times++;
@@ -1438,17 +1429,17 @@  again:
 		goto enable_and_dump;
 
 	if (tried_times >= pci_try_num) {
-		if (pci_realloc_enable == undefined)
-			printk(KERN_INFO "Some PCI device resources are unassigned, try booting with pci=realloc\n");
-		else if (pci_realloc_enable == auto_enabled)
-			printk(KERN_INFO "Automatically enabled pci realloc, if you have problem, try booting with pci=realloc=off\n");
+		if (enable_local == undefined)
+			dev_info(&bus->dev, "Some PCI device resources are unassigned, try booting with pci=realloc\n");
+		else if (enable_local == auto_enabled)
+			dev_info(&bus->dev, "Automatically enabled pci realloc, if you have problem, try booting with pci=realloc=off\n");
 
 		free_list(&fail_head);
 		goto enable_and_dump;
 	}
 
-	printk(KERN_DEBUG "PCI: No. %d try to assign unassigned res\n",
-			 tried_times + 1);
+	dev_printk(KERN_DEBUG, &bus->dev,
+		   "No. %d try to assign unassigned res\n", tried_times + 1);
 
 	/* third times and later will not check if it is leaf */
 	if ((tried_times + 1) > 2)
@@ -1458,12 +1449,11 @@  again:
 	 * Try to release leaf bridge's resources that doesn't fit resource of
 	 * child device under that bridge
 	 */
-	list_for_each_entry(fail_res, &fail_head, list) {
-		bus = fail_res->dev->bus;
-		pci_bus_release_bridge_resources(bus,
+	list_for_each_entry(fail_res, &fail_head, list)
+		pci_bus_release_bridge_resources(fail_res->dev->bus,
 						 fail_res->flags & type_mask,
 						 rel_type);
-	}
+
 	/* restore size and flags */
 	list_for_each_entry(fail_res, &fail_head, list) {
 		struct resource *res = fail_res->res;
@@ -1480,12 +1470,19 @@  again:
 
 enable_and_dump:
 	/* Depth last, update the hardware. */
-	list_for_each_entry(bus, &pci_root_buses, node)
-		pci_enable_bridges(bus);
+	pci_enable_bridges(bus);
 
 	/* dump the resource on buses */
+	pci_bus_dump_resources(bus);
+}
+
+void __init
+pci_assign_unassigned_resources(void)
+{
+	struct pci_bus *bus;
+
 	list_for_each_entry(bus, &pci_root_buses, node)
-		pci_bus_dump_resources(bus);
+		pci_assign_unassigned_root_bus_resources(bus);
 }
 
 void pci_assign_unassigned_bridge_resources(struct pci_dev *bridge)