On 2015/2/4 18:18, Stefani Seibold wrote:
> The example is intended for int types, not for strings. So it is not a
> bug, it's a feature ;-) But anyway, if you prefer to handle with strings
> your are okay by me.
>
hi,Stefani Seibold
Thanks you for your reply. another question?
This example export the interface '/proc/int-fifo', and how to use it?
Write and read it through system call, or the command `cat` and `echo`?
Best Regards
Wang Long
> Am Dienstag, den 03.02.2015, 11:51 +0000 schrieb Wang Long:
>> echo 99 > /proc/int-fifo ------------> Never return
>> echo 1000 > /proc/int-fifo ------------> Never return
>>
>> this patch fix it.
>>
>> Signed-off-by: Wang Long <long.wangl...@huawei.com>
>> ---
>> samples/kfifo/inttype-example.c | 51
>> ++++++++++++++++++++++++++++++++---------
>> 1 file changed, 40 insertions(+), 11 deletions(-)
>>
>> diff --git a/samples/kfifo/inttype-example.c
>> b/samples/kfifo/inttype-example.c
>> index 8dc3c2e..cc0db5f 100644
>> --- a/samples/kfifo/inttype-example.c
>> +++ b/samples/kfifo/inttype-example.c
>> @@ -6,6 +6,7 @@
>> * Released under the GPL version 2 only.
>> *
>> */
>> +#include <asm/uaccess.h>
>>
>> #include <linux/init.h>
>> #include <linux/module.h>
>> @@ -23,6 +24,9 @@
>> /* name of the proc entry */
>> #define PROC_FIFO "int-fifo"
>>
>> +/* Worst case buffer size needed for holding an integer. */
>> +#define PROC_NUMBUF 13
>> +
>> /* lock for procfs read access */
>> static DEFINE_MUTEX(read_lock);
>>
>> @@ -108,33 +112,58 @@ static int __init testfunc(void)
>> static ssize_t fifo_write(struct file *file, const char __user *buf,
>> size_t count, loff_t *ppos)
>> {
>> - int ret;
>> - unsigned int copied;
>> + char buffer[PROC_NUMBUF];
>> + int value;
>> + int err;
>>
>> - if (mutex_lock_interruptible(&write_lock))
>> - return -ERESTARTSYS;
>> + memset(buffer, 0, sizeof(buffer));
>>
>> - ret = kfifo_from_user(&test, buf, count, &copied);
>> + if (count > sizeof(buffer) - 1)
>> + count = sizeof(buffer) - 1;
>> + if (copy_from_user(buffer, buf, count)) {
>> + err = -EFAULT;
>> + goto out;
>> + }
>>
>> - mutex_unlock(&write_lock);
>> + err = kstrtoint(strstrip(buffer), 0, &value);
>> + if (err)
>> + goto out;
>> +
>> + if (kfifo_is_full(&test)) {
>> + err = -EINVAL;
>> + goto out;
>> + }
>>
>> - return ret ? ret : copied;
>> + if (mutex_lock_interruptible(&write_lock))
>> + return -ERESTARTSYS;
>> + kfifo_put(&test, value);
>> + mutex_unlock(&write_lock);
>> +out:
>> + return err < 0 ? err : count;
>> }
>>
>> static ssize_t fifo_read(struct file *file, char __user *buf,
>> size_t count, loff_t *ppos)
>> {
>> - int ret;
>> - unsigned int copied;
>> + char buffer[PROC_NUMBUF * FIFO_SIZE];
>> + int value;
>> + size_t len = 0;
>> + ssize_t ret = -1;
>> +
>> + memset(buffer, 0, sizeof(buffer));
>>
>> if (mutex_lock_interruptible(&read_lock))
>> return -ERESTARTSYS;
>>
>> - ret = kfifo_to_user(&test, buf, count, &copied);
>> + while (!kfifo_is_empty(&test)){
>> + ret = kfifo_get(&test, &value);
>> + len = snprintf(buffer, sizeof(buffer), "%s%d\n", buffer, value);
>> + }
>>
>> mutex_unlock(&read_lock);
>> + ret = copy_to_user(buf, buffer, len);
>>
>> - return ret ? ret : copied;
>> + return ret ? ret : len;
>> }
>>
>> static const struct file_operations fifo_fops = {
>
>
>
> .
>
--
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