Re: [PATCH 2/8] v2 Add section count to memory_block struct

2010-09-28 Thread Robin Holt 
In the next patch, you introduce a mutex for adding/removing memory blocks.
Is there really a need for this to be atomic?  If you reorder the patches
so the mutex comes first, would the atomic be needed any longer?

Robin

On Mon, Sep 27, 2010 at 02:22:24PM -0500, Nathan Fontenot wrote:
 Add a section count property to the memory_block struct to track the number
 of memory sections that have been added/removed from a memory block. This
 allows us to know when the last memory section of a memory block has been
 removed so we can remove the memory block.
 
 Signed-off-by: Nathan Fontenot nf...@austin.ibm.com
 
 ---
  drivers/base/memory.c  |   16 ++--
  include/linux/memory.h |3 +++
  2 files changed, 13 insertions(+), 6 deletions(-)
 
 Index: linux-next/drivers/base/memory.c
 ===
 --- linux-next.orig/drivers/base/memory.c 2010-09-27 09:17:20.0 
 -0500
 +++ linux-next/drivers/base/memory.c  2010-09-27 09:31:35.0 -0500
 @@ -478,6 +478,7 @@
  
   mem-phys_index = __section_nr(section);
   mem-state = state;
 + atomic_inc(mem-section_count);
   mutex_init(mem-state_mutex);
   start_pfn = section_nr_to_pfn(mem-phys_index);
   mem-phys_device = arch_get_memory_phys_device(start_pfn);
 @@ -505,12 +506,15 @@
   struct memory_block *mem;
  
   mem = find_memory_block(section);
 - unregister_mem_sect_under_nodes(mem);
 - mem_remove_simple_file(mem, phys_index);
 - mem_remove_simple_file(mem, state);
 - mem_remove_simple_file(mem, phys_device);
 - mem_remove_simple_file(mem, removable);
 - unregister_memory(mem, section);
 +
 + if (atomic_dec_and_test(mem-section_count)) {
 + unregister_mem_sect_under_nodes(mem);
 + mem_remove_simple_file(mem, phys_index);
 + mem_remove_simple_file(mem, state);
 + mem_remove_simple_file(mem, phys_device);
 + mem_remove_simple_file(mem, removable);
 + unregister_memory(mem, section);
 + }
  
   return 0;
  }
 Index: linux-next/include/linux/memory.h
 ===
 --- linux-next.orig/include/linux/memory.h2010-09-27 09:17:20.0 
 -0500
 +++ linux-next/include/linux/memory.h 2010-09-27 09:22:56.0 -0500
 @@ -19,10 +19,13 @@
  #include linux/node.h
  #include linux/compiler.h
  #include linux/mutex.h
 +#include asm/atomic.h
  
  struct memory_block {
   unsigned long phys_index;
   unsigned long state;
 + atomic_t section_count;
 +
   /*
* This serializes all state change requests.  It isn't
* held during creation because the control files are
 
 
 --
 To unsubscribe from this list: send the line unsubscribe linux-kernel in
 the body of a message to majord...@vger.kernel.org
 More majordomo info at  http://vger.kernel.org/majordomo-info.html
 Please read the FAQ at  http://www.tux.org/lkml/
___
Linuxppc-dev mailing list
Linuxppc-dev@lists.ozlabs.org
https://lists.ozlabs.org/listinfo/linuxppc-dev

Re: [PATCH 2/8] v2 Add section count to memory_block struct

2010-09-28 Thread Nathan Fontenot 
On 09/28/2010 04:31 AM, Robin Holt wrote:
 In the next patch, you introduce a mutex for adding/removing memory blocks.
 Is there really a need for this to be atomic?  If you reorder the patches
 so the mutex comes first, would the atomic be needed any longer?
 

I think you're right.  Looking at the code with all patches applied I am only
updating the atomic when holding the mem_sysfs_mutex.  I think the atomic
could safely be changed to a regular int.

-Nathan

 Robin
 
 On Mon, Sep 27, 2010 at 02:22:24PM -0500, Nathan Fontenot wrote:
 Add a section count property to the memory_block struct to track the number
 of memory sections that have been added/removed from a memory block. This
 allows us to know when the last memory section of a memory block has been
 removed so we can remove the memory block.

 Signed-off-by: Nathan Fontenot nf...@austin.ibm.com

 ---
  drivers/base/memory.c  |   16 ++--
  include/linux/memory.h |3 +++
  2 files changed, 13 insertions(+), 6 deletions(-)

 Index: linux-next/drivers/base/memory.c
 ===
 --- linux-next.orig/drivers/base/memory.c2010-09-27 09:17:20.0 
 -0500
 +++ linux-next/drivers/base/memory.c 2010-09-27 09:31:35.0 -0500
 @@ -478,6 +478,7 @@
  
  mem-phys_index = __section_nr(section);
  mem-state = state;
 +atomic_inc(mem-section_count);
  mutex_init(mem-state_mutex);
  start_pfn = section_nr_to_pfn(mem-phys_index);
  mem-phys_device = arch_get_memory_phys_device(start_pfn);
 @@ -505,12 +506,15 @@
  struct memory_block *mem;
  
  mem = find_memory_block(section);
 -unregister_mem_sect_under_nodes(mem);
 -mem_remove_simple_file(mem, phys_index);
 -mem_remove_simple_file(mem, state);
 -mem_remove_simple_file(mem, phys_device);
 -mem_remove_simple_file(mem, removable);
 -unregister_memory(mem, section);
 +
 +if (atomic_dec_and_test(mem-section_count)) {
 +unregister_mem_sect_under_nodes(mem);
 +mem_remove_simple_file(mem, phys_index);
 +mem_remove_simple_file(mem, state);
 +mem_remove_simple_file(mem, phys_device);
 +mem_remove_simple_file(mem, removable);
 +unregister_memory(mem, section);
 +}
  
  return 0;
  }
 Index: linux-next/include/linux/memory.h
 ===
 --- linux-next.orig/include/linux/memory.h   2010-09-27 09:17:20.0 
 -0500
 +++ linux-next/include/linux/memory.h2010-09-27 09:22:56.0 
 -0500
 @@ -19,10 +19,13 @@
  #include linux/node.h
  #include linux/compiler.h
  #include linux/mutex.h
 +#include asm/atomic.h
  
  struct memory_block {
  unsigned long phys_index;
  unsigned long state;
 +atomic_t section_count;
 +
  /*
   * This serializes all state change requests.  It isn't
   * held during creation because the control files are


 --
 To unsubscribe from this list: send the line unsubscribe linux-kernel in
 the body of a message to majord...@vger.kernel.org
 More majordomo info at  http://vger.kernel.org/majordomo-info.html
 Please read the FAQ at  http://www.tux.org/lkml/

___
Linuxppc-dev mailing list
Linuxppc-dev@lists.ozlabs.org
https://lists.ozlabs.org/listinfo/linuxppc-dev

[PATCH 2/8] v2 Add section count to memory_block struct

2010-09-27 Thread Nathan Fontenot 
Add a section count property to the memory_block struct to track the number
of memory sections that have been added/removed from a memory block. This
allows us to know when the last memory section of a memory block has been
removed so we can remove the memory block.

Signed-off-by: Nathan Fontenot nf...@austin.ibm.com

---
 drivers/base/memory.c  |   16 ++--
 include/linux/memory.h |3 +++
 2 files changed, 13 insertions(+), 6 deletions(-)

Index: linux-next/drivers/base/memory.c
===
--- linux-next.orig/drivers/base/memory.c   2010-09-27 09:17:20.0 
-0500
+++ linux-next/drivers/base/memory.c2010-09-27 09:31:35.0 -0500
@@ -478,6 +478,7 @@
 
mem-phys_index = __section_nr(section);
mem-state = state;
+   atomic_inc(mem-section_count);
mutex_init(mem-state_mutex);
start_pfn = section_nr_to_pfn(mem-phys_index);
mem-phys_device = arch_get_memory_phys_device(start_pfn);
@@ -505,12 +506,15 @@
struct memory_block *mem;
 
mem = find_memory_block(section);
-   unregister_mem_sect_under_nodes(mem);
-   mem_remove_simple_file(mem, phys_index);
-   mem_remove_simple_file(mem, state);
-   mem_remove_simple_file(mem, phys_device);
-   mem_remove_simple_file(mem, removable);
-   unregister_memory(mem, section);
+
+   if (atomic_dec_and_test(mem-section_count)) {
+   unregister_mem_sect_under_nodes(mem);
+   mem_remove_simple_file(mem, phys_index);
+   mem_remove_simple_file(mem, state);
+   mem_remove_simple_file(mem, phys_device);
+   mem_remove_simple_file(mem, removable);
+   unregister_memory(mem, section);
+   }
 
return 0;
 }
Index: linux-next/include/linux/memory.h
===
--- linux-next.orig/include/linux/memory.h  2010-09-27 09:17:20.0 
-0500
+++ linux-next/include/linux/memory.h   2010-09-27 09:22:56.0 -0500
@@ -19,10 +19,13 @@
 #include linux/node.h
 #include linux/compiler.h
 #include linux/mutex.h
+#include asm/atomic.h
 
 struct memory_block {
unsigned long phys_index;
unsigned long state;
+   atomic_t section_count;
+
/*
 * This serializes all state change requests.  It isn't
 * held during creation because the control files are


___
Linuxppc-dev mailing list
Linuxppc-dev@lists.ozlabs.org
https://lists.ozlabs.org/listinfo/linuxppc-dev