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    Subject[PATCH v7 3/4] drivers/base/node.c: use bin_attribute to break the size limitation of cpumap ABI
    Date
    From: Tian Tao <tiantao6@hisilicon.com>

    Reading /sys/devices/system/cpu/cpuX/nodeX/ returns cpumap and cpulist.
    However, the size of this file is limited to PAGE_SIZE because of the
    limitation for sysfs attribute.

    This patch moves to use bin_attribute to extend the ABI to be more
    than one page so that cpumap bitmask and list won't be potentially
    trimmed.

    Signed-off-by: Tian Tao <tiantao6@hisilicon.com>
    Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    Cc: "Rafael J. Wysocki" <rafael@kernel.org>
    Signed-off-by: Barry Song <song.bao.hua@hisilicon.com>
    ---
    -v7:
    sys -> /sys, thanks for Andy's comments

    drivers/base/node.c | 51 +++++++++++++++++++++++++++++----------------
    1 file changed, 33 insertions(+), 18 deletions(-)

    diff --git a/drivers/base/node.c b/drivers/base/node.c
    index 4a4ae868ad9f..89a72aba72a3 100644
    --- a/drivers/base/node.c
    +++ b/drivers/base/node.c
    @@ -27,42 +27,44 @@ static struct bus_type node_subsys = {
    };


    -static ssize_t node_read_cpumap(struct device *dev, bool list, char *buf)
    +static ssize_t node_read_cpumap(struct device *dev, bool list, char *buf,
    + loff_t off, size_t count)
    {
    ssize_t n;
    cpumask_var_t mask;
    struct node *node_dev = to_node(dev);

    - /* 2008/04/07: buf currently PAGE_SIZE, need 9 chars per 32 bits. */
    - BUILD_BUG_ON((NR_CPUS/32 * 9) > (PAGE_SIZE-1));
    -
    if (!alloc_cpumask_var(&mask, GFP_KERNEL))
    return 0;

    cpumask_and(mask, cpumask_of_node(node_dev->dev.id), cpu_online_mask);
    - n = cpumap_print_to_pagebuf(list, buf, mask);
    + n = cpumap_print_to_buf(list, buf, mask, off, count);
    free_cpumask_var(mask);

    return n;
    }

    -static inline ssize_t cpumap_show(struct device *dev,
    - struct device_attribute *attr,
    - char *buf)
    +static inline ssize_t cpumap_read(struct file *file, struct kobject *kobj,
    + struct bin_attribute *attr, char *buf,
    + loff_t off, size_t count)
    {
    - return node_read_cpumap(dev, false, buf);
    + struct device *dev = kobj_to_dev(kobj);
    +
    + return node_read_cpumap(dev, false, buf, off, count);
    }

    -static DEVICE_ATTR_RO(cpumap);
    +static BIN_ATTR_RO(cpumap, 0);

    -static inline ssize_t cpulist_show(struct device *dev,
    - struct device_attribute *attr,
    - char *buf)
    +static inline ssize_t cpulist_read(struct file *file, struct kobject *kobj,
    + struct bin_attribute *attr, char *buf,
    + loff_t off, size_t count)
    {
    - return node_read_cpumap(dev, true, buf);
    + struct device *dev = kobj_to_dev(kobj);
    +
    + return node_read_cpumap(dev, true, buf, off, count);
    }

    -static DEVICE_ATTR_RO(cpulist);
    +static BIN_ATTR_RO(cpulist, 0);

    /**
    * struct node_access_nodes - Access class device to hold user visible
    @@ -557,15 +559,28 @@ static ssize_t node_read_distance(struct device *dev,
    static DEVICE_ATTR(distance, 0444, node_read_distance, NULL);

    static struct attribute *node_dev_attrs[] = {
    - &dev_attr_cpumap.attr,
    - &dev_attr_cpulist.attr,
    &dev_attr_meminfo.attr,
    &dev_attr_numastat.attr,
    &dev_attr_distance.attr,
    &dev_attr_vmstat.attr,
    NULL
    };
    -ATTRIBUTE_GROUPS(node_dev);
    +
    +static struct bin_attribute *node_dev_bin_attrs[] = {
    + &bin_attr_cpumap,
    + &bin_attr_cpulist,
    + NULL
    +};
    +
    +static const struct attribute_group node_dev_group = {
    + .attrs = node_dev_attrs,
    + .bin_attrs = node_dev_bin_attrs
    +};
    +
    +static const struct attribute_group *node_dev_groups[] = {
    + &node_dev_group,
    + NULL
    +};

    #ifdef CONFIG_HUGETLBFS
    /*
    --
    2.25.1
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