linux-kernel - Re: [PATCH 2/2] cciss: Fix SCSI device reset handler

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Date:	Fri, 29 May 2009 12:42:08 -0700
From:	Andrew Morton <akpm@...ux-foundation.org>
To:	scameron@...rdog.cca.cpqcorp.net
Cc:	linux-kernel@...r.kernel.org, linux-scsi@...r.kernel.org,
	axboe@...nel.dk, mikem@...rdog.cca.cpqcorp.net,
	scameron@...rdog.cca.cpqcorp.net
Subject: Re: [PATCH 2/2] cciss: Fix SCSI device reset handler

On Wed, 27 May 2009 15:30:07 -0500
scameron@...rdog.cca.cpqcorp.net wrote:

> +static int wait_for_device_to_become_ready(ctlr_info_t *h,
> +	unsigned char lunaddr[])
> +{
> +	int rc;
> +	int count = 0;
> +	int waittime = HZ;
> +	CommandList_struct *c;
> +
> +	c = cmd_alloc(h, 1);
> +	if (!c) {
> +		printk(KERN_WARNING "cciss%d: out of memory in "
> +			"wait_for_device_to_become_ready.\n", h->ctlr);
> +		return IO_ERROR;
> +	}
> +
> +	/* Send test unit ready until device ready, or give up. */
> +	while (count < 20) {
> +
> +		/* Wait for a bit.  do this first, because if we send
> +		 * the TUR right away, the reset will just abort it.
> +		 */
> +		set_current_state(TASK_INTERRUPTIBLE);
> +		schedule_timeout(waittime);

That's schedule_timeout_interruptible().

The problem with interruptible sleeps of this nature is that they are
no-ops if the calling process happens to have signal_pending().  I
suspect that this condition will break your driver.

If so, switching to schedule_timeout_uninterruptible() will unbreak it.

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