Re: wait_for_completion_interruptible does not wait !! [During PM suspend]

Re: wait_for_completion_interruptible does not wait !! [During PM suspend]

[Suresh Rajashekara]

On Sun, Jun 20, 2010 at 12:23 AM, Jiri Slaby <jirislaby@gmail.com> wrote:
> On 06/20/2010 08:52 AM, Suresh Rajashekara wrote:
>> The ioctl waits on a completion variable (using
>> wait_for_completion_interruptible).
> ...
>> I tried wait_for_completion instead, but now the kernel refuses to suspend.
>
> Do you check return value of wait_for_completion_interruptible and
> return its value if nonzero?
>
> We need the code to comment, otherwise it's hard to say.

No. I am not checking the return value of the
wait_for_completion_interruptible. I can do it

The code is as follows. I have cut the relevant portion of the code
and pasted in to the email

My test application. The actual application is exactly similar (actual
application has different names)
<SNIP>
void *headset_detect_thread_start ( void *private_date )
{
    int hs_fd = 0;
    int iState = 0;

    hs_fd = open("/dev/adc", O_RDWR);

    if ( hs_fd == -1 ) {
        printf("The headset device could not be opened\n");
        goto hs_thread_exit;
    }

    for (;;) {
       pthread_testcancel();
       ioctl(hs_fd, IOCTL_CODEC_HEADSET_DETECT, &iState);
       pthread_testcancel();

       if ( iState )
           printf("\n++++ Headset Insertion detected\n");
       else
           printf("\n---- Headset Removal detected\n");

       SignalEvent(); // Dummy function, but the actual application
does inside the function
    }

hs_thread_out:
    close(hs_fd);
hs_thread_exit:
    pthread_exit(NULL);
}
</SNIP>


Kernel Code:

/* Code from Ioctl of the codec driver*/
<SNIP>
 case IOCTL_CODEC_HEADSET_DETECT:
       headset_detect();
       headset_detect_state = get_hsdetect_state();
       copy_to_user( argp, &headset_detect_state, sizeof(int)) ;
       break;
</SNIP>

implementation of headset_detect in the codec driver
<SNIP>
void headset_detect(void){
	/* This variable is completed in interrupt handler */
    wait_for_completion_interruptible(&drv_priv->headset_completion);
}
</SNIP>

Thanks,
Suresh

Re: wait_for_completion_interruptible does not wait !! [During PM suspend]

[Jiri Slaby]

On 06/20/2010 09:42 AM, Suresh Rajashekara wrote:
> On Sun, Jun 20, 2010 at 12:23 AM, Jiri Slaby <jirislaby@gmail.com> wrote:
>> On 06/20/2010 08:52 AM, Suresh Rajashekara wrote:
>>> The ioctl waits on a completion variable (using
>>> wait_for_completion_interruptible).
>> ...
>>> I tried wait_for_completion instead, but now the kernel refuses to suspend.
>>
>> Do you check return value of wait_for_completion_interruptible and
>> return its value if nonzero?
>>
>> We need the code to comment, otherwise it's hard to say.
> 
> No. I am not checking the return value of the
> wait_for_completion_interruptible. I can do it

I thought so. Generally, all *_interruptible functions return a value
which should be checked and propagated to upper layers.

-- 
js