-----Original Message----- From: tiantao (H) Sent: Thursday, May 27, 2021 2:57 PM To: Song Bao Hua (Barry Song) <song.bao.hua@hisilicon.com>; Jonathan Cameron <jonathan.cameron@huawei.com> Cc: linuxarm@openeuler.org; tiantao (H) <tiantao6@hisilicon.com> Subject: [PATCH v7] topology: use bin_attribute to avoid buff overflow
Reading sys/devices/system/cpu/cpuX/topology/ returns cpu topology. However, the size of this file is limited to PAGE_SIZE because of the limitation for sysfs attribute. so we use bin_attribute instead of attribute to avoid NR_CPUS too big to cause buff overflow.
This patch is based on the following discussion. https://www.spinics.net/lists/linux-doc/msg95921.html
Signed-off-by: Tian Tao <tiantao6@hisilicon.com> --- v2: rewrite the function name##_read v3: remove the temp buffer. v4: rewrite the function name##_read v5: rewrite the patch v6: update the commit message v7: remove BUFF_SIZE, dynamic calculation of size --- drivers/base/topology.c | 144
Thanks very much. We are almost there.
+++++++++++++++++++++++++++++++----------------- 1 file changed, 94 insertions(+), 50 deletions(-)
diff --git a/drivers/base/topology.c b/drivers/base/topology.c index 4d254fc..883fa39 100644 --- a/drivers/base/topology.c +++ b/drivers/base/topology.c @@ -21,24 +21,59 @@ static ssize_t name##_show(struct device *dev, \ return sysfs_emit(buf, "%d\n", topology_##name(dev->id)); \ }
-#define define_siblings_show_map(name, mask) \ -static ssize_t name##_show(struct device *dev, \ - struct device_attribute *attr, char *buf) \ -{ \ - return cpumap_print_to_pagebuf(false, buf, topology_##mask(dev->id));\ -} +static int topology_snprintf(char *buf, ssize_t size, const char *fmt, ...) +{ + va_list args; + int i;
As discussed, better to make a common wrapper so that other modules calling cpumap_print_to_pagebuf, such as drivers/base/node.c, can reuse the wrapper.
-#define define_siblings_show_list(name, mask) \ -static ssize_t name##_list_show(struct device *dev, \ - struct device_attribute *attr, \ - char *buf) \ -{ \ - return cpumap_print_to_pagebuf(true, buf, topology_##mask(dev->id));\ + va_start(args, fmt); + if (size <= 0) + i = vsnprintf(NULL, 0, fmt, args); + else + i = vscnprintf(buf, size, fmt, args); + va_end(args); + + return i; }
-#define define_siblings_show_func(name, mask) \ - define_siblings_show_map(name, mask); \ - define_siblings_show_list(name, mask) +#define define_siblings_read_func(name, mask) \ +static ssize_t name##_read(struct file *file, struct kobject *kobj, \ + struct bin_attribute *attr, char *buf, \ + loff_t off, size_t count) \ +{ \ + struct device *dev = kobj_to_dev(kobj); \ + int len; \ + void *data; \ + len = topology_snprintf(NULL, 0, "%*pb\n", nr_cpu_ids, \ + cpumask_bits(topology_##mask(dev->id))); \ + data = kvmalloc(len+1, GFP_KERNEL); \ + if (!data) \ + return -ENOMEM; \ + len = topology_snprintf(data, len+1, "%*pb\n", nr_cpu_ids, \ + cpumask_bits(topology_##mask(dev->id))); \ + len = memory_read_from_buffer(buf, count, &off, data, len); \ + kvfree(data); \ + return len; \ +} \ + \ +static ssize_t name##_list_read(struct file *file, struct kobject *kobj, \ + struct bin_attribute *attr, char *buf, \ + loff_t off, size_t count) \ +{ \ + struct device *dev = kobj_to_dev(kobj); \ + int len; \ + void *data; \ + len = topology_snprintf(NULL, 0, "%*pbl\n", nr_cpu_ids, \ + cpumask_bits(topology_##mask(dev->id))); \ + data = kvmalloc(len+1, GFP_KERNEL); \ + if (!data) \ + return -ENOMEM; \ + len = topology_snprintf(data, len+1, "%*pbl\n", nr_cpu_ids, \ + cpumask_bits(topology_##mask(dev->id))); \ + len = memory_read_from_buffer(buf, count, &off, data, len); \ + kvfree(data); \ + return len; \ +}
As discussed, here we have some bad smells in code. The only difference between name##_list_read and name##_read is pb and pbl. Thanks Barry