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Message-Id: <1362384208-6687-1-git-send-email-Russ.Dill@gmail.com>
Date: Mon, 4 Mar 2013 00:03:28 -0800
From: Russ Dill <russ.dill@...il.com>
To: stable@...nel.org, linux-kernel <linux-kernel@...r.kernel.org>
Cc: Al Viro <viro@...iv.linux.org.uk>,
Nick Kossifidis <mickflemm@...il.com>,
Theodore Ts'o <tytso@....edu>
Subject: [PATCH] Revert "random: Mix cputime from each thread that exits to the pool"
This reverts commit 6133705494bb02953e1e2cc3018a4373981b3c97.
The above commit introduces a circular locking dependacy. Existing code
takes nonblocking_port.lock and then tasklist_lock. The code in this
commit takes nonblocking_port.lock while talklist_lock is already held
leading to a potential deadlock. For now, simply revert the commit.
Existing lock order:
send_sigio /* takes read lock on tasklist_lock */
kill_fasync_rcu
kill_fasync
account /* takes nonblocking_pool.lock */
extract_entropy
get_random_bytes
create_elf_tables
load_elf_binary
load_elf_library
search_binary_handler
New code:
mix_pool_bytes /* takes nonblocking_pool.lock */
add_device_randomness
posix_cpu_timers_exit
__exit_signal
release_task /* takes write lock on tasklist_lock */
do_exit
__module_put_and_exit
cryptomgr_test
Signed-off-by: Russ Dill <Russ.Dill@...il.com>
---
kernel/posix-cpu-timers.c | 3 ---
1 file changed, 3 deletions(-)
diff --git a/kernel/posix-cpu-timers.c b/kernel/posix-cpu-timers.c
index 942ca27..1f2ef3d 100644
--- a/kernel/posix-cpu-timers.c
+++ b/kernel/posix-cpu-timers.c
@@ -9,7 +9,6 @@
#include <asm/uaccess.h>
#include <linux/kernel_stat.h>
#include <trace/events/timer.h>
-#include <linux/random.h>
/*
* Called after updating RLIMIT_CPU to run cpu timer and update
@@ -471,8 +470,6 @@ static void cleanup_timers(struct list_head *head,
*/
void posix_cpu_timers_exit(struct task_struct *tsk)
{
- add_device_randomness((const void*) &tsk->se.sum_exec_runtime,
- sizeof(unsigned long long));
cleanup_timers(tsk->cpu_timers,
tsk->utime, tsk->stime, tsk->se.sum_exec_runtime);
--
1.8.1.2
--
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