On Tuesday 24 August 2004 05:26, Dhiman, Gaurav wrote:
>
> I am getting some problem in it ....... The problem is that when I
> load the module and read the module created "/proc/timer_wait" file
> using 'head' or 'cat' command, then my timer_read_proc() function
> (see the use_timer.c file in attachment) is called by kernel twice.
Sounds correct. Cat will have something similar to the following (but
hopefully with error checks :-)
while ((n = read(fd, buf, 1000)) > 0) {
write(1, buf, n);
}
For a file less then 1000 bytes, how many times will read() be called?
> I am not able to understand why it is called two times. I am
> attaching the output of 'dmesg' command. The attached text file
> (dmesg_output.txt) contains only the kernel messages related to my
> module.
>
> The output of reading process is that, for the first time it displays
> what I want it to display but after that it displays garbage and it
> also make the shell prompt filled with garbage ..... it does not show
> ascii characters after that on shell prompt.
You don't appear to be taking off_set into account in your read handler.
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