lkml.org 
[lkml]   [2010]   [Sep]   [28]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [PATCH 2/8] v2 Add section count to memory_block struct
    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 <nfont@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 09:17:20.000000000 -0500
    >> +++ linux-next/drivers/base/memory.c 2010-09-27 09:31:35.000000000 -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 09:17:20.000000000 -0500
    >> +++ linux-next/include/linux/memory.h 2010-09-27 09:22:56.000000000 -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 majordomo@vger.kernel.org
    >> More majordomo info at http://vger.kernel.org/majordomo-info.html
    >> Please read the FAQ at http://www.tux.org/lkml/



    \
     
     \ /
      Last update: 2010-09-28 20:17    [W:0.045 / U:29.568 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site