Messages in this thread | | | Date | Wed, 27 Dec 2017 13:47:26 +0100 | From | Greg KH <> | Subject | Re: [RFC PATCH] memory-hotplug: add sysfs immovable_mem attribute |
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On Wed, Dec 27, 2017 at 08:30:12PM +0800, Chao Fan wrote: > In sometimes users specify the memory region in immovable node in > some kernel commandline, such as "kernel_core" or the "immovable_mem=" > in the patchset that I have send. But users don't know the memory > region. So add this interface to print it. > > It will show like this: "nn@ss,nn@ss,...". "nn" means the size of memory > region, "ss" means the start position of this region. > > Signed-off-by: Chao Fan <fanc.fnst@cn.fujitsu.com> > --- > drivers/base/memory.c | 50 ++++++++++++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 50 insertions(+)
Why did you not also create the needed Documentation/ABI/ file update?
That's required for sysfs attributes.
> > diff --git a/drivers/base/memory.c b/drivers/base/memory.c > index 1d60b58a8c19..9cadf1a9dccb 100644 > --- a/drivers/base/memory.c > +++ b/drivers/base/memory.c > @@ -25,6 +25,7 @@ > > #include <linux/atomic.h> > #include <linux/uaccess.h> > +#include <linux/acpi.h> > > static DEFINE_MUTEX(mem_sysfs_mutex); > > @@ -389,6 +390,52 @@ static ssize_t show_phys_device(struct device *dev, > } > > #ifdef CONFIG_MEMORY_HOTREMOVE > +/* > + * Immovable memory region > + */ > + > +static ssize_t > +show_immovable_mem(struct device *dev, struct device_attribute *attr, > + char *buf) > +{ > + struct acpi_table_header *table_header = NULL; > + struct acpi_srat_mem_affinity *ma; > + struct acpi_subtable_header *th; > + unsigned long long table_size; > + unsigned long long table_end; > + char pbuf[35], *p = buf; > + int len; > + > + acpi_get_table(ACPI_SIG_SRAT, 0, &table_header); > + > + table_size = sizeof(struct acpi_table_srat); > + table_end = (unsigned long)table_header + table_header->length; > + th = (struct acpi_subtable_header *)((unsigned long) > + table_header + table_size); > + > + while (((unsigned long)th) + > + sizeof(struct acpi_subtable_header) < table_end) { > + if (th->type == 1) { > + ma = (struct acpi_srat_mem_affinity *)th; > + if (ma->flags & ACPI_SRAT_MEM_HOT_PLUGGABLE) > + continue; > + len = sprintf(pbuf, "%llx@%llx", > + ma->length, ma->base_address);
sysfs is "one value per file", and if you ever have to care if you are overrunning the length of the buffer, that's a huge hint you are doing something wrong here.
sorry,
greg k-h
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