Use stop_machine_run in the Intel RNG driver

Replace call_smp_function with stop_machine_run in the Intel RNG driver.

CPU A has done read_lock(&lock)
CPU B has done write_lock_irq(&lock) and is waiting for A to release the lock.

A third CPU calls call_smp_function and issues the IPI.  CPU A takes CPU
C's IPI.  CPU B is waiting with interrupts disabled and does not see the
IPI.  CPU C is stuck waiting for CPU B to respond to the IPI.

Deadlock.

The solution is to use stop_machine_run instead of call_smp_function
(call_smp_function should not be called in situations where the CPUs may be
suspended).

[haruo.tomita@toshiba.co.jp: fix a typo in mod_init()]
[haruo.tomita@toshiba.co.jp: fix memory leak]
Signed-off-by: Prarit Bhargava <prarit@redhat.com>
Cc: Jan Beulich <jbeulich@novell.com>
Cc: "Tomita, Haruo" <haruo.tomita@toshiba.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 5 insertions, 3 deletions

diff --git a/kernel/stop_machine.c b/kernel/stop_machine.c
index 1245804..daabb74 100644
--- a/kernel/stop_machine.c
+++ b/kernel/stop_machine.c
@@ -1,11 +1,12 @@
 /* Copyright 2005 Rusty Russell rusty@rustcorp.com.au IBM Corporation.
  * GPL v2 and any later version.
  */
-#include <linux/stop_machine.h>
-#include <linux/kthread.h>
-#include <linux/sched.h>
 #include <linux/cpu.h>
 #include <linux/err.h>
+#include <linux/kthread.h>
+#include <linux/module.h>
+#include <linux/sched.h>
+#include <linux/stop_machine.h>
 #include <linux/syscalls.h>
 #include <asm/atomic.h>
 #include <asm/semaphore.h>
@@ -208,3 +209,4 @@ int stop_machine_run(int (*fn)(void *), void *data, unsigned int cpu)
 
 	return ret;
 }
+EXPORT_SYMBOL_GPL(stop_machine_run);