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Date: Wed, 28 Jul 2004 16:00:33 -0700
From: Andrew Morton <akpm@osdl.org>
To: Greg Howard <ghoward@sgi.com>
Cc: linux-kernel@vger.kernel.org
Subject: Re: [PATCH] Altix system controller communication driver
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Greg Howard <ghoward@sgi.com> wrote:
>
> > > +static unsigned int
> > > +scdrv_poll(struct file *file, struct poll_table_struct *wait)
> > > +{
> > > +	unsigned int mask = 0;
> > > +	int status = 0;
> > > +	struct subch_data_s *sd = (struct subch_data_s *) file->private_data;
> > > +	unsigned long flags;
> > > +
> > > +	scdrv_lock_all(sd, &flags);
> > > +	poll_wait(file, &sd->sd_rq, wait);
> > > +	poll_wait(file, &sd->sd_wq, wait);
> >
> > This function will sleep with spinlocks held, won't it?
> 
> My understanding is that poll_wait just sets up a poll_table
> structure; it doesn't sleep itself.

It calls into __pollwait(), which can perform sleeping memory allocations.