From 25d5cb4b0375e5864ec0ccf35e12ff1d1b5cf3f0 Mon Sep 17 00:00:00 2001
From: David Brownell <david-b@pacbell.net>
Date: Fri, 23 May 2008 13:05:03 -0700
Subject: [PATCH] spi: remove some spidev oops-on-rmmod paths

Somehow the spidev code forgot to include a critical mechanism: when the
underlying device is removed (e.g.  spi_master rmmod), open file
descriptors must be prevented from issuing new I/O requests to that
device.  On penalty of the oopsing reported by Sebastian Siewior
<bigeasy@tglx.de> ...

This is a partial fix, adding handshaking between the lower level (SPI
messaging) and the file operations using the spi_dev.  (It also fixes an
issue where reads and writes didn't return the number of bytes sent or
received.)

There's still a refcounting issue to be addressed (separately).

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Reported-by: Sebastian Siewior <bigeasy@tglx.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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