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From: Ian Munsie <imunsie@au1.ibm.com>
To: Michael Neuling <mikey@neuling.org>
Subject: Re: [PATCH v4 13/16] cxl: Driver code for powernv PCIe based cards
 for userspace access
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 <1412758505-23495-14-git-send-email-mikey@neuling.org>
Date: Wed, 08 Oct 2014 21:28:05 +1100
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Cc: cbe-oss-dev <cbe-oss-dev@lists.ozlabs.org>, arnd <arnd@arndb.de>,
 "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>, greg <greg@kroah.com>,
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Excerpts from Michael Neuling's message of 2014-10-08 19:55:02 +1100:
> +static ssize_t afu_read(struct file *file, char __user *buf, size_t count,
> +            loff_t *off)
...
> +    for (;;) {
> +        prepare_to_wait(&ctx->wq, &wait, TASK_INTERRUPTIBLE);
> +        if (ctx_event_pending(ctx))
> +            break;
> +
> +        spin_unlock_irqrestore(&ctx->lock, flags);
> +        if (file->f_flags & O_NONBLOCK)
> +            return -EAGAIN;
> +
> +        if (signal_pending(current))
> +            return -ERESTARTSYS;

Looks like I mucked this up while refactoring - these two cases no
longer call finish_wait() which can lead to a crash if something later
wakes up the ctx->wq... I'll post a fix in a separate patch shortly.

-Ian