Re: [PATCH 3/10] kdump: export per cpu crash notes pointer through sysfs
From: Vivek Goyal
Date: Fri Nov 18 2005 - 07:33:12 EST
On Thu, Nov 17, 2005 at 02:07:23PM -0800, Andrew Morton wrote:
> Vivek Goyal <vgoyal@xxxxxxxxxx> wrote:
> > + /*
> > + * Might be reading other cpu's data based on which cpu read thread
> > + * has been scheduled. But cpu data (memory) is allocated once during
> > + * boot up and this data does not change there after. Hence this
> > + * operation should be safe. No locking required.
> > + */
> > + get_cpu();
> > + addr = __pa(per_cpu_ptr(crash_notes, cpunum));
> > + rc = sprintf(buf, "%Lx\n", addr);
> > + put_cpu();
> I don't think the get_cpu() and put_cpu() are needed here?
Thanks. I have done the changes. Please find attached the incremental patch.
o Removes the call to get_cpu() and put_cpu() as it is not required.
Signed-off-by: Vivek Goyal <vgoyal@xxxxxxxxxx>
linux-2.6.15-rc1-mm2-1M-root/drivers/base/cpu.c | 2 --
1 files changed, 2 deletions(-)
diff -puN drivers/base/cpu.c~kdump-export-crash-notes-sysfs-remove-get-cpu drivers/base/cpu.c
--- linux-2.6.15-rc1-mm2-1M/drivers/base/cpu.c~kdump-export-crash-notes-sysfs-remove-get-cpu 2005-11-18 16:08:28.000000000 +0530
+++ linux-2.6.15-rc1-mm2-1M-root/drivers/base/cpu.c 2005-11-18 16:08:28.000000000 +0530
@@ -101,10 +101,8 @@ static ssize_t show_crash_notes(struct s
* boot up and this data does not change there after. Hence this
* operation should be safe. No locking required.
addr = __pa(per_cpu_ptr(crash_notes, cpunum));
rc = sprintf(buf, "%Lx\n", addr);
static SYSDEV_ATTR(crash_notes, 0400, show_crash_notes, NULL);
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