linux-kernel - Re: [PATCH 1/1] UML: fix missing non-blocking I/O, now DEBUG

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Date:	Mon, 11 Jun 2007 13:31:54 -0400
From:	Jeff Dike <jdike@...toit.com>
To:	Eduard-Gabriel Munteanu <maxdamage@...din.ro>
Cc:	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/1] UML: fix missing non-blocking I/O, now DEBUG_SHIRQ works

On Mon, Jun 11, 2007 at 01:01:57AM +0300, Eduard-Gabriel Munteanu wrote:
> DEBUG_SHIRQ generates spurious interrupts, triggering handlers such as 
> mconsole_interrupt() or line_interrupt(). They expect data to be 
> available to be read from their sockets/pipes, but in the case of 
> spurious interrupts, the host didn't actually send anything, so UML 
> hangs in read() and friends. Setting those fd's as O_NONBLOCK makes 
> DEBUG_SHIRQ-enabled UML kernels boot and run correctly. 

Nice.

I don't really like this section though.  The casting I have now isn't
pleasant, but I don't like adding a new global to get rid of it.

> diff --git a/arch/um/drivers/mconsole_kern.c b/arch/um/drivers/mconsole_kern.c
> index 542c9ef..02d132e 100644
> --- a/arch/um/drivers/mconsole_kern.c
> +++ b/arch/um/drivers/mconsole_kern.c
> @@ -74,12 +74,11 @@ static DECLARE_WORK(mconsole_work, mc_work_proc);
>  
>  static irqreturn_t mconsole_interrupt(int irq, void *dev_id)
>  {
> -	/* long to avoid size mismatch warnings from gcc */
> -	long fd;
> +	int fd;
>  	struct mconsole_entry *new;
>  	static struct mc_request req;	/* that's OK */
>  
> -	fd = (long) dev_id;
> +	fd = *((int *) dev_id);
>  	while (mconsole_get_request(fd, &req)){
>  		if(req.cmd->context == MCONSOLE_INTR)
>  			(*req.cmd->handler)(&req);
> @@ -798,10 +797,10 @@ void mconsole_stack(struct mc_request *req)
>   */
>  static char *notify_socket = NULL;
>  
> +static int sock;
> +
>  static int mconsole_init(void)
>  {
> -	/* long to avoid size mismatch warnings from gcc */
> -	long sock;
>  	int err;
>  	char file[256];
>  
> @@ -818,7 +817,7 @@ static int mconsole_init(void)
>  
>  	err = um_request_irq(MCONSOLE_IRQ, sock, IRQ_READ, mconsole_interrupt,
>  			     IRQF_DISABLED | IRQF_SHARED | IRQF_SAMPLE_RANDOM,
> -			     "mconsole", (void *)sock);
> +			     "mconsole", &sock);
>  	if (err){
>  		printk("Failed to get IRQ for management console\n");
>  		return(1);

				Jeff

-- 
Work email - jdike at linux dot intel dot com
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