Re: [BUG] NULL pointer deref with rcutorture

Paul E. McKenney
2009-01-06T02:15:31Z

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On Mon, Jan 05, 2009 at 04:29:12PM -0800, Paul E. McKenney wrote:
> On Mon, Jan 05, 2009 at 02:18:36PM -0800, Paul E. McKenney wrote:
> > On Mon, Jan 05, 2009 at 09:31:53PM +0100, Eric Sesterhenn wrote:
> > > * Paul E. McKenney (paulmck@linux.vnet.ibm.com) wrote:
> > > > On Mon, Jan 05, 2009 at 09:01:45PM +0100, Eric Sesterhenn wrote:
> > > > > hi,
> > > > >
> > > > > * Paul E. McKenney (paulmck@linux.vnet.ibm.com) wrote:
> > > > > > On Mon, Jan 05, 2009 at 07:56:55PM +0100, Eric Sesterhenn wrote:
> > > > > >
> > > > > > Wow!!! Am I reading this correctly? Does the above "call" instruction
> > > > > > -really- call one byte into itself? That is what the hex for the x86
> > > > > > instruction -looks- like it is doing, but I cannot see what would have
> > > > > > possessed the compiler to generate this code.
> > > > >
> > > > > Compiler is gcc version 4.2.4 (Ubuntu 4.2.4-1ubuntu3)
> > > >
> > > > I am using 4.1.3, for whatever it is worth. (Ancient, I know!)
> > > >
> > > > > > When I compile on a 32-bit x86 machine, I don't see the above "call"
> > > > > > instruction. Other than that, the code I see looks consistent.
> > > > > >
> > > > > > > 9f0: eb 1d jmp a0f <rcu_stutter_wait+0x27>
> > > > > > > 9f2: 83 3d 00 00 00 00 00 cmpl $0x0,0x0
> > > > > > > 9f9: b8 01 00 00 00 mov $0x1,%eax
> > > > > > > 9fe: 75 0a jne a0a <rcu_stutter_wait+0x22>
> > > > > > > a00: b8 e8 03 00 00 mov $0x3e8,%eax
> > > > > > > a05: e8 fc ff ff ff call a06 <rcu_stutter_wait+0x1e>
> > > > > > > a0a: e8 fc ff ff ff call a0b <rcu_stutter_wait+0x23>
> > > > > > > a0f: 83 3d 6c 00 00 00 00 cmpl $0x0,0x6c
> > > > > > > ^---------- this line
> > > > > >
> > > > > > This looks like the first test in the "while" loop.
> > > > > >
> > > > > > > a16: 75 09 jne a21 <rcu_stutter_wait+0x39>
> > > > > > > a18: 83 3d 00 00 00 00 00 cmpl $0x0,0x0
> > > > > > > a1f: 75 09 jne a2a <rcu_stutter_wait+0x42>
> > > > > > > a21: 83 3d 50 1a 00 00 00 cmpl $0x0,0x1a50
> > > > > > > a28: 74 c8 je 9f2 <rcu_stutter_wait+0xa>
> > > > > > > a2a: 5d pop %ebp
> > > > > > > a2b: c3 ret
> > > > > >
> > > > > > The corresponding C code is as follows:
> > > > > >
> > > > > > static void
> > > > > > rcu_stutter_wait(void)
> > > > > > {
> > > > > > while ((stutter_pause_test || !rcutorture_runnable) && !fullstop) {
> > > > > > if (rcutorture_runnable)
> > > > > > schedule_timeout_interruptible(1);
> > > > > > else
> > > > > > schedule_timeout_interruptible(round_jiffies_relative(HZ));
> > > > > > }
> > > > > > }
> > > > > >
> > > > > > I don't see much opportunity for a page fault here... This is the
> > > > > > binary I get when I compile it, though not as a module:
> > > > > >
> > > > > > 0000085a <rcu_stutter_wait>:
> > > > > > 85a: 55 push %ebp
> > > > > > 85b: 89 e5 mov %esp,%ebp
> > > > > > 85d: eb 1d jmp 87c <rcu_stutter_wait+0x22>
> > > > > > 85f: 83 3d 00 00 00 00 00 cmpl $0x0,0x0
> > > > > > 866: b8 01 00 00 00 mov $0x1,%eax
> > > > > > 86b: 75 0a jne 877 <rcu_stutter_wait+0x1d>
> > > > > > 86d: b8 e8 03 00 00 mov $0x3e8,%eax
> > > > > > 872: e8 fc ff ff ff call 873 <rcu_stutter_wait+0x19>
> > > > > > 877: e8 fc ff ff ff call 878 <rcu_stutter_wait+0x1e>
> > > > > > 87c: 83 3d 14 00 00 00 00 cmpl $0x0,0x14
> > > > > > 883: 75 09 jne 88e <rcu_stutter_wait+0x34>
> > > > > > 885: 83 3d 00 00 00 00 00 cmpl $0x0,0x0
> > > > > > 88c: 75 09 jne 897 <rcu_stutter_wait+0x3d>
> > > > > > 88e: 83 3d 08 1a 00 00 00 cmpl $0x0,0x1a08
> > > > > > 895: 74 c8 je 85f <rcu_stutter_wait+0x5>
> > > > > > 897: 5d pop %ebp
> > > > > > 898: c3 ret
> > > > > >
> > > > > > I confess, I am confused!!!
> > > > >
> > > > > on the other box with a different gcc version
> > > > >
> > > > > gcc version 4.3.2 (Ubuntu 4.3.2-1ubuntu11)
> > > > >
> > > > > d1902e90 is the start of rcu_stutter_wait
> > > > >
> > > > > [ 533.391719] d087e000 d1902e90
> > > > > [ 533.392294] rcu-torture:--- Start of test: nreaders=2 nfakewriters=4 stat_interval=0 verbose=0 test_no_idle_hz=0 shuffle_interval=3 stutter=5 irqreader=1
> > > > > [ 541.000139] BUG: unable to handle kernel paging request at d1902efd
> > > > > [ 541.000423] IP: [<d1902efd>] 0xd1902efd
> > > > > [ 541.000660] *pde = 0f08f067 *pte = 00000000
> > > > > [ 541.000867] Oops: 0000 [#1] DEBUG_PAGEALLOC
> > > > > [ 541.001126] last sysfs file: /sys/block/sda/size
> > > > > [ 541.001246] Modules linked in: nfsd exportfs nfs lockd nfs_acl auth_rpcgss sunrpc ipv6 fuse unix [last unloaded: rcutorture]
> > > > > [ 541.002235]
> > > > > [ 541.002334] Pid: 5292, comm: rcu_torture_wri Not tainted (2.6.28 #84)
> > > > > [ 541.002470] EIP: 0060:[<d1902efd>] EFLAGS: 00010296 CPU: 0
> > > > > [ 541.002598] EIP is at 0xd1902efd
> > > > > [ 541.002767] EAX: 00000000 EBX: d19073c0 ECX: 00000000 EDX: 00000000
> > > > > [ 541.002900] ESI: 0000000a EDI: 00000000 EBP: c7b63fb8 ESP: c7b63fb8
> > > > > [ 541.003033] DS: 007b ES: 007b FS: 0000 GS: 0000 SS: 0068
> > > > > [ 541.003160] Process rcu_torture_wri (pid: 5292, ti=c7b63000 task=c7b09710 task.ti=c7b63000)
> > > > > [ 541.003400] Stack:
> > > > > [ 541.003497] c7b63fd0 d19032c1 00000000 00000000 00000000 d1903200 c7b63fe0 c013d80a
> > > > > [ 541.004022] c013d7d0 00000000 00000000 c0103cf3 cef6ee70 00000000 00000000 00000000
> > > > > [ 541.004022] 00000201 000004b4
> > > > > [ 541.004022] Call Trace:
> > > > > [ 541.004022] [<c013d80a>] ? kthread+0x3a/0x70
> > > > > [ 541.004022] [<c013d7d0>] ? kthread+0x0/0x70
> > > > > [ 541.004022] [<c0103cf3>] ? kernel_thread_helper+0x7/0x14
> > > > > [ 541.004022] Code: Bad EIP value.
> > > > > [ 541.004022] EIP: [<d1902efd>] 0xd1902efd SS:ESP 0068:c7b63fb8
> > > > > [ 541.004022] ---[ end trace cb3b10c2bb94b4e3 ]---
> > > > >
> > > > >
> > > > > 00000e90 <rcu_stutter_wait>:
> > > > > e90: 55 push %ebp
> > > > > e91: 89 e5 mov %esp,%ebp
> > > > > e93: 90 nop
> > > > > e94: 8d 74 26 00 lea 0x0(%esi,%eiz,1),%esi
> > > > > e98: a1 98 00 00 00 mov 0x98,%eax
> > > > > e9d: 85 c0 test %eax,%eax
> > > > > e9f: 75 09 jne eaa <rcu_stutter_wait+0x1a>
> > > > > ea1: a1 00 00 00 00 mov 0x0,%eax
> > > > > ea6: 85 c0 test %eax,%eax
> > > > > ea8: 75 36 jne ee0 <rcu_stutter_wait+0x50>
> > > > > eaa: a1 88 1a 00 00 mov 0x1a88,%eax
> > > > > eaf: 85 c0 test %eax,%eax
> > > > > eb1: 75 2d jne ee0 <rcu_stutter_wait+0x50>
> > > > > eb3: 8b 15 00 00 00 00 mov 0x0,%edx
> > > > > eb9: 85 d2 test %edx,%edx
> > > > > ebb: 74 2b je ee8 <rcu_stutter_wait+0x58>
> > > > > ebd: b8 01 00 00 00 mov $0x1,%eax
> > > > > ec2: e8 fc ff ff ff call ec3 <rcu_stutter_wait+0x33>
> > > > > ec7: a1 98 00 00 00 mov 0x98,%eax
> > > > > ecc: 85 c0 test %eax,%eax
> > > > > ece: 74 d1 je ea1 <rcu_stutter_wait+0x11>
> > > > > ed0: a1 88 1a 00 00 mov 0x1a88,%eax
> > > > > ed5: 85 c0 test %eax,%eax
> > > > > ed7: 74 da je eb3 <rcu_stutter_wait+0x23>
> > > > > ed9: 8d b4 26 00 00 00 00 lea 0x0(%esi,%eiz,1),%esi
> > > > > ee0: 5d pop %ebp
> > > > > ee1: c3 ret
> > > > > ee2: 8d b6 00 00 00 00 lea 0x0(%esi),%esi
> > > > > ee8: b8 fa 00 00 00 mov $0xfa,%eax
> > > > > eed: e8 fc ff ff ff call eee <rcu_stutter_wait+0x5e>
> > > >
> > > > Here we are again calling one byte into the current instruction!!!
> > > >
> > > > Or am I misinterpreting this code?
> > > >
> > > > > ef2: 8d b6 00 00 00 00 lea 0x0(%esi),%esi
> > > > > ef8: e8 fc ff ff ff call ef9 <rcu_stutter_wait+0x69>
> > > > > efd: 8d 76 00 lea 0x0(%esi),%esi
> > > > > ^------------- here
> > > > >
> > > > > This one looks more like it can explain a page fault
> > > >
> > > > I don't understand why there are indirections in the assembly given the
> > > > C code for rcu_stutter_wait().
> > > >
> > > > > f00: eb 96 jmp e98 <rcu_stutter_wait+0x8>
> > > > > f02: 8d b4 26 00 00 00 00 lea 0x0(%esi,%eiz,1),%esi
> > > > > f09: 8d bc 27 00 00 00 00 lea 0x0(%edi,%eiz,1),%edi
> > >
> > > ok, after trying to find out if the ubuntu gccs are broken, i stumbled
> > > upon this:
> > > http://forum.soft32.com/linux/Strange-problem-disassembling-shared-lib-ftopict439936.html
> > >
> > > Seems the difference is that you dont compile it as a module and the
> > > jump is perfectly normal, it gets overwritten when the stuff is loaded
> > > objdump -dr gives me
> > >
> > > 00000e90 <rcu_stutter_wait>:
> > > e90: 55 push %ebp
> > > e91: 89 e5 mov %esp,%ebp
> > > e93: 90 nop
> > > e94: 8d 74 26 00 lea 0x0(%esi,%eiz,1),%esi
> > > e98: a1 98 00 00 00 mov 0x98,%eax
> > > e99: R_386_32 .bss
> > > e9d: 85 c0 test %eax,%eax
> > > e9f: 75 09 jne eaa <rcu_stutter_wait+0x1a>
> > > ea1: a1 00 00 00 00 mov 0x0,%eax
> > > ea2: R_386_32 rcutorture_runnable
> > > ea6: 85 c0 test %eax,%eax
> > > ea8: 75 36 jne ee0 <rcu_stutter_wait+0x50>
> > > eaa: a1 88 1a 00 00 mov 0x1a88,%eax
> > > eab: R_386_32 .bss
> > > eaf: 85 c0 test %eax,%eax
> > > eb1: 75 2d jne ee0 <rcu_stutter_wait+0x50>
> > > eb3: 8b 15 00 00 00 00 mov 0x0,%edx
> > > eb5: R_386_32 rcutorture_runnable
> > > eb9: 85 d2 test %edx,%edx
> > > ebb: 74 2b je ee8 <rcu_stutter_wait+0x58>
> > > ebd: b8 01 00 00 00 mov $0x1,%eax
> > > ec2: e8 fc ff ff ff call ec3 <rcu_stutter_wait+0x33>
> > > ec3: R_386_PC32 schedule_timeout_interruptible
> > > ec7: a1 98 00 00 00 mov 0x98,%eax
> > > ec8: R_386_32 .bss
> > > ecc: 85 c0 test %eax,%eax
> > > ece: 74 d1 je ea1 <rcu_stutter_wait+0x11>
> > > ed0: a1 88 1a 00 00 mov 0x1a88,%eax
> > > ed1: R_386_32 .bss
> > > ed5: 85 c0 test %eax,%eax
> > > ed7: 74 da je eb3 <rcu_stutter_wait+0x23>
> > > ed9: 8d b4 26 00 00 00 00 lea 0x0(%esi,%eiz,1),%esi
> > > ee0: 5d pop %ebp
> > > ee1: c3 ret
> > > ee2: 8d b6 00 00 00 00 lea 0x0(%esi),%esi
> > > ee8: b8 fa 00 00 00 mov $0xfa,%eax
> > > eed: e8 fc ff ff ff call eee <rcu_stutter_wait+0x5e>
> > > eee: R_386_PC32 round_jiffies_relative
> > > ef2: 8d b6 00 00 00 00 lea 0x0(%esi),%esi
> > > ef8: e8 fc ff ff ff call ef9 <rcu_stutter_wait+0x69>
> > > ef9: R_386_PC32 schedule_timeout_interruptible
> > > efd: 8d 76 00 lea 0x0(%esi),%esi
> > >
> > > here is the deref ------------------------^
> >
> > Ah!!! We are getting a page fault while cleaning up the stack frame?
> >
> > Ouch!
> >
> > > f00: eb 96 jmp e98 <rcu_stutter_wait+0x8>
> > > f02: 8d b4 26 00 00 00 00 lea 0x0(%esi,%eiz,1),%esi
> > > f09: 8d bc 27 00 00 00 00 lea 0x0(%edi,%eiz,1),%edi
>
> And now I can run this. gcc v3.4.4 gives yet a different error:
>
> divide error: 0000 [#1] PREEMPT SMP
> last sysfs file: /sys/devices/pci0000:00/0000:00:0a.0/0000:02:04.0/host0/target0:0:6/0:0:6:0/type
> CPU 1
> Modules linked in: [last unloaded: rcutorture]
> Pid: 3369, comm: rcu_torture_rea Not tainted 2.6.28-autokern1 #1
> RIP: 0010:[<ffffffffa0000142>] [<ffffffffa0000142>] 0xffffffffa0000142
> RSP: 0000:ffff88007f0afeb0 EFLAGS: 00010246
> RAX: 00000000def36d6a RBX: ffffffffa0006850 RCX: 0000000000000000
> RDX: 0000000000000000 RSI: ffff88007ecf1600 RDI: ffff88007f0afef0
> RBP: 0000000000000dd4 R08: ffff88007f0ae000 R09: ffffffff8037c7d9
> R10: 0000000000000000 R11: ffffffff8037c7d9 R12: 0000000000000000
> R13: 000000000000000a R14: 0000000000000000 R15: 0000000000000000
> FS: 0000000000000000(0000) GS:ffff8800e3801c00(0000) knlGS:00000000f7f3ab80
> CS: 0010 DS: 0018 ES: 0018 CR0: 000000008005003b
> CR2: 00000000080dc87c CR3: 0000000000201000 CR4: 00000000000006e0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
> Process rcu_torture_rea (pid: 3369, threadinfo ffff88007f0ae000, task ffff88007ecf5d80)
> Stack:
> ffffffff8037c7d9 ffffffffa000090d ffff88007ecfdec0 ffff88007ec17eb0
> 0000000000000001 ffffffffa00006e6 0000000000000000 ffff8800e3488000
> c744ca136d6adef3 0000000000000256 0000000000000000 ffffffffa0000807
> Call Trace:
> [<ffffffff8037c7d9>] ? delay_tsc+0x0/0x99
> [<ffffffff80245b94>] ? kthread+0x3d/0x63
> [<ffffffff8020c3ea>] ? child_rip+0xa/0x20
> [<ffffffff80245b57>] ? kthread+0x0/0x63
> [<ffffffff8020c3e0>] ? child_rip+0x0/0x20
> Code: 58 c3 56 bf 01 00 00 00 e8 88 bd 22 e0 59 31 c0 c3 41 51 e8 69 ff ff ff 48 63 15 0a 58 00 00 48 69 d2 90 01 00 00 48 89 d1 31 d2 <48> f7 f1 48 85 d2 75 0c 41 58 bf 78 1b 0d 00 e9 32 c7 37 e0 5f
> RIP [<ffffffffa0000142>] 0xffffffffa0000142
> RSP <ffff88007f0afeb0>
>
> I will see what I can find from this.

Hello, Eric,

Just for grins, I built the 2.6.28 kernel/rcutorture.c on b58602a. It
insmoded and rmmoded without errors.

Could you please try this on your setup? I have attached this file in
case that helps.

Thanx, Paul

[-- Attachment #2: kernel/rcutorture.c --]
[-- Type: text/x-csrc, Size: 31855 bytes --]

/*
* Read-Copy Update module-based torture test facility
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*
* Copyright (C) IBM Corporation, 2005, 2006
*
* Authors: Paul E. McKenney <paulmck@us.ibm.com>
* Josh Triplett <josh@freedesktop.org>
*
* See also: Documentation/RCU/torture.txt
*/
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/kthread.h>
#include <linux/err.h>
#include <linux/spinlock.h>
#include <linux/smp.h>
#include <linux/rcupdate.h>
#include <linux/interrupt.h>
#include <linux/sched.h>
#include <asm/atomic.h>
#include <linux/bitops.h>
#include <linux/completion.h>
#include <linux/moduleparam.h>
#include <linux/percpu.h>
#include <linux/notifier.h>
#include <linux/freezer.h>
#include <linux/cpu.h>
#include <linux/delay.h>
#include <linux/stat.h>
#include <linux/srcu.h>
#include <linux/slab.h>
#include <asm/byteorder.h>

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Paul E. McKenney <paulmck@us.ibm.com> and "
"Josh Triplett <josh@freedesktop.org>");

static int nreaders = -1; /* # reader threads, defaults to 2*ncpus */
static int nfakewriters = 4; /* # fake writer threads */
static int stat_interval; /* Interval between stats, in seconds. */
/* Defaults to "only at end of test". */
static int verbose; /* Print more debug info. */
static int test_no_idle_hz; /* Test RCU's support for tickless idle CPUs. */
static int shuffle_interval = 3; /* Interval between shuffles (in sec)*/
static int stutter = 5; /* Start/stop testing interval (in sec) */
static int irqreader = 1; /* RCU readers from irq (timers). */
static char *torture_type = "rcu"; /* What RCU implementation to torture. */

module_param(nreaders, int, 0444);
MODULE_PARM_DESC(nreaders, "Number of RCU reader threads");
module_param(nfakewriters, int, 0444);
MODULE_PARM_DESC(nfakewriters, "Number of RCU fake writer threads");
module_param(stat_interval, int, 0444);
MODULE_PARM_DESC(stat_interval, "Number of seconds between stats printk()s");
module_param(verbose, bool, 0444);
MODULE_PARM_DESC(verbose, "Enable verbose debugging printk()s");
module_param(test_no_idle_hz, bool, 0444);
MODULE_PARM_DESC(test_no_idle_hz, "Test support for tickless idle CPUs");
module_param(shuffle_interval, int, 0444);
MODULE_PARM_DESC(shuffle_interval, "Number of seconds between shuffles");
module_param(stutter, int, 0444);
MODULE_PARM_DESC(stutter, "Number of seconds to run/halt test");
module_param(irqreader, int, 0444);
MODULE_PARM_DESC(irqreader, "Allow RCU readers from irq handlers");
module_param(torture_type, charp, 0444);
MODULE_PARM_DESC(torture_type, "Type of RCU to torture (rcu, rcu_bh, srcu)");

#define TORTURE_FLAG "-torture:"
#define PRINTK_STRING(s) \
do { printk(KERN_ALERT "%s" TORTURE_FLAG s "\n", torture_type); } while (0)
#define VERBOSE_PRINTK_STRING(s) \
do { if (verbose) printk(KERN_ALERT "%s" TORTURE_FLAG s "\n", torture_type); } while (0)
#define VERBOSE_PRINTK_ERRSTRING(s) \
do { if (verbose) printk(KERN_ALERT "%s" TORTURE_FLAG "!!! " s "\n", torture_type); } while (0)

static char printk_buf[4096];

static int nrealreaders;
static struct task_struct *writer_task;
static struct task_struct **fakewriter_tasks;
static struct task_struct **reader_tasks;
static struct task_struct *stats_task;
static struct task_struct *shuffler_task;
static struct task_struct *stutter_task;

#define RCU_TORTURE_PIPE_LEN 10

struct rcu_torture {
struct rcu_head rtort_rcu;
int rtort_pipe_count;
struct list_head rtort_free;
int rtort_mbtest;
};

static int fullstop = 0; /* stop generating callbacks at test end. */
static LIST_HEAD(rcu_torture_freelist);
static struct rcu_torture *rcu_torture_current = NULL;
static long rcu_torture_current_version = 0;
static struct rcu_torture rcu_tortures[10 * RCU_TORTURE_PIPE_LEN];
static DEFINE_SPINLOCK(rcu_torture_lock);
static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_count) =
{ 0 };
static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_batch) =
{ 0 };
static atomic_t rcu_torture_wcount[RCU_TORTURE_PIPE_LEN + 1];
static atomic_t n_rcu_torture_alloc;
static atomic_t n_rcu_torture_alloc_fail;
static atomic_t n_rcu_torture_free;
static atomic_t n_rcu_torture_mberror;
static atomic_t n_rcu_torture_error;
static long n_rcu_torture_timers = 0;
static struct list_head rcu_torture_removed;

static int stutter_pause_test = 0;

#if defined(MODULE) || defined(CONFIG_RCU_TORTURE_TEST_RUNNABLE)
#define RCUTORTURE_RUNNABLE_INIT 1
#else
#define RCUTORTURE_RUNNABLE_INIT 0
#endif
int rcutorture_runnable = RCUTORTURE_RUNNABLE_INIT;

/*
* Allocate an element from the rcu_tortures pool.
*/
static struct rcu_torture *
rcu_torture_alloc(void)
{
struct list_head *p;

spin_lock_bh(&rcu_torture_lock);
if (list_empty(&rcu_torture_freelist)) {
atomic_inc(&n_rcu_torture_alloc_fail);
spin_unlock_bh(&rcu_torture_lock);
return NULL;
}
atomic_inc(&n_rcu_torture_alloc);
p = rcu_torture_freelist.next;
list_del_init(p);
spin_unlock_bh(&rcu_torture_lock);
return container_of(p, struct rcu_torture, rtort_free);
}

/*
* Free an element to the rcu_tortures pool.
*/
static void
rcu_torture_free(struct rcu_torture *p)
{
atomic_inc(&n_rcu_torture_free);
spin_lock_bh(&rcu_torture_lock);
list_add_tail(&p->rtort_free, &rcu_torture_freelist);
spin_unlock_bh(&rcu_torture_lock);
}

struct rcu_random_state {
unsigned long rrs_state;
long rrs_count;
};

#define RCU_RANDOM_MULT 39916801 /* prime */
#define RCU_RANDOM_ADD 479001701 /* prime */
#define RCU_RANDOM_REFRESH 10000

#define DEFINE_RCU_RANDOM(name) struct rcu_random_state name = { 0, 0 }

/*
* Crude but fast random-number generator. Uses a linear congruential
* generator, with occasional help from cpu_clock().
*/
static unsigned long
rcu_random(struct rcu_random_state *rrsp)
{
if (--rrsp->rrs_count < 0) {
rrsp->rrs_state +=
(unsigned long)cpu_clock(raw_smp_processor_id());
rrsp->rrs_count = RCU_RANDOM_REFRESH;
}
rrsp->rrs_state = rrsp->rrs_state * RCU_RANDOM_MULT + RCU_RANDOM_ADD;
return swahw32(rrsp->rrs_state);
}

static void
rcu_stutter_wait(void)
{
while (stutter_pause_test || !rcutorture_runnable)
if (rcutorture_runnable)
schedule_timeout_interruptible(1);
else
schedule_timeout_interruptible(round_jiffies_relative(HZ));
}

/*
* Operations vector for selecting different types of tests.
*/

struct rcu_torture_ops {
void (*init)(void);
void (*cleanup)(void);
int (*readlock)(void);
void (*readdelay)(struct rcu_random_state *rrsp);
void (*readunlock)(int idx);
int (*completed)(void);
void (*deferredfree)(struct rcu_torture *p);
void (*sync)(void);
void (*cb_barrier)(void);
int (*stats)(char *page);
int irqcapable;
char *name;
};
static struct rcu_torture_ops *cur_ops = NULL;

/*
* Definitions for rcu torture testing.
*/

static int rcu_torture_read_lock(void) __acquires(RCU)
{
rcu_read_lock();
return 0;
}

static void rcu_read_delay(struct rcu_random_state *rrsp)
{
long delay;
const long longdelay = 200;

/* We want there to be long-running readers, but not all the time. */

delay = rcu_random(rrsp) % (nrealreaders * 2 * longdelay);
if (!delay)
udelay(longdelay);
}

static void rcu_torture_read_unlock(int idx) __releases(RCU)
{
rcu_read_unlock();
}

static int rcu_torture_completed(void)
{
return rcu_batches_completed();
}

static void
rcu_torture_cb(struct rcu_head *p)
{
int i;
struct rcu_torture *rp = container_of(p, struct rcu_torture, rtort_rcu);

if (fullstop) {
/* Test is ending, just drop callbacks on the floor. */
/* The next initialization will pick up the pieces. */
return;
}
i = rp->rtort_pipe_count;
if (i > RCU_TORTURE_PIPE_LEN)
i = RCU_TORTURE_PIPE_LEN;
atomic_inc(&rcu_torture_wcount[i]);
if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
rp->rtort_mbtest = 0;
rcu_torture_free(rp);
} else
cur_ops->deferredfree(rp);
}

static void rcu_torture_deferred_free(struct rcu_torture *p)
{
call_rcu(&p->rtort_rcu, rcu_torture_cb);
}

static struct rcu_torture_ops rcu_ops = {
.init = NULL,
.cleanup = NULL,
.readlock = rcu_torture_read_lock,
.readdelay = rcu_read_delay,
.readunlock = rcu_torture_read_unlock,
.completed = rcu_torture_completed,
.deferredfree = rcu_torture_deferred_free,
.sync = synchronize_rcu,
.cb_barrier = rcu_barrier,
.stats = NULL,
.irqcapable = 1,
.name = "rcu"
};

static void rcu_sync_torture_deferred_free(struct rcu_torture *p)
{
int i;
struct rcu_torture *rp;
struct rcu_torture *rp1;

cur_ops->sync();
list_add(&p->rtort_free, &rcu_torture_removed);
list_for_each_entry_safe(rp, rp1, &rcu_torture_removed, rtort_free) {
i = rp->rtort_pipe_count;
if (i > RCU_TORTURE_PIPE_LEN)
i = RCU_TORTURE_PIPE_LEN;
atomic_inc(&rcu_torture_wcount[i]);
if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
rp->rtort_mbtest = 0;
list_del(&rp->rtort_free);
rcu_torture_free(rp);
}
}
}

static void rcu_sync_torture_init(void)
{
INIT_LIST_HEAD(&rcu_torture_removed);
}

static struct rcu_torture_ops rcu_sync_ops = {
.init = rcu_sync_torture_init,
.cleanup = NULL,
.readlock = rcu_torture_read_lock,
.readdelay = rcu_read_delay,
.readunlock = rcu_torture_read_unlock,
.completed = rcu_torture_completed,
.deferredfree = rcu_sync_torture_deferred_free,
.sync = synchronize_rcu,
.cb_barrier = NULL,
.stats = NULL,
.irqcapable = 1,
.name = "rcu_sync"
};

/*
* Definitions for rcu_bh torture testing.
*/

static int rcu_bh_torture_read_lock(void) __acquires(RCU_BH)
{
rcu_read_lock_bh();
return 0;
}

static void rcu_bh_torture_read_unlock(int idx) __releases(RCU_BH)
{
rcu_read_unlock_bh();
}

static int rcu_bh_torture_completed(void)
{
return rcu_batches_completed_bh();
}

static void rcu_bh_torture_deferred_free(struct rcu_torture *p)
{
call_rcu_bh(&p->rtort_rcu, rcu_torture_cb);
}

struct rcu_bh_torture_synchronize {
struct rcu_head head;
struct completion completion;
};

static void rcu_bh_torture_wakeme_after_cb(struct rcu_head *head)
{
struct rcu_bh_torture_synchronize *rcu;

rcu = container_of(head, struct rcu_bh_torture_synchronize, head);
complete(&rcu->completion);
}

static void rcu_bh_torture_synchronize(void)
{
struct rcu_bh_torture_synchronize rcu;

init_completion(&rcu.completion);
call_rcu_bh(&rcu.head, rcu_bh_torture_wakeme_after_cb);
wait_for_completion(&rcu.completion);
}

static struct rcu_torture_ops rcu_bh_ops = {
.init = NULL,
.cleanup = NULL,
.readlock = rcu_bh_torture_read_lock,
.readdelay = rcu_read_delay, /* just reuse rcu's version. */
.readunlock = rcu_bh_torture_read_unlock,
.completed = rcu_bh_torture_completed,
.deferredfree = rcu_bh_torture_deferred_free,
.sync = rcu_bh_torture_synchronize,
.cb_barrier = rcu_barrier_bh,
.stats = NULL,
.irqcapable = 1,
.name = "rcu_bh"
};

static struct rcu_torture_ops rcu_bh_sync_ops = {
.init = rcu_sync_torture_init,
.cleanup = NULL,
.readlock = rcu_bh_torture_read_lock,
.readdelay = rcu_read_delay, /* just reuse rcu's version. */
.readunlock = rcu_bh_torture_read_unlock,
.completed = rcu_bh_torture_completed,
.deferredfree = rcu_sync_torture_deferred_free,
.sync = rcu_bh_torture_synchronize,
.cb_barrier = NULL,
.stats = NULL,
.irqcapable = 1,
.name = "rcu_bh_sync"
};

/*
* Definitions for srcu torture testing.
*/

static struct srcu_struct srcu_ctl;

static void srcu_torture_init(void)
{
init_srcu_struct(&srcu_ctl);
rcu_sync_torture_init();
}

static void srcu_torture_cleanup(void)
{
synchronize_srcu(&srcu_ctl);
cleanup_srcu_struct(&srcu_ctl);
}

static int srcu_torture_read_lock(void) __acquires(&srcu_ctl)
{
return srcu_read_lock(&srcu_ctl);
}

static void srcu_read_delay(struct rcu_random_state *rrsp)
{
long delay;
const long uspertick = 1000000 / HZ;
const long longdelay = 10;

/* We want there to be long-running readers, but not all the time. */

delay = rcu_random(rrsp) % (nrealreaders * 2 * longdelay * uspertick);
if (!delay)
schedule_timeout_interruptible(longdelay);
}

static void srcu_torture_read_unlock(int idx) __releases(&srcu_ctl)
{
srcu_read_unlock(&srcu_ctl, idx);
}

static int srcu_torture_completed(void)
{
return srcu_batches_completed(&srcu_ctl);
}

static void srcu_torture_synchronize(void)
{
synchronize_srcu(&srcu_ctl);
}

static int srcu_torture_stats(char *page)
{
int cnt = 0;
int cpu;
int idx = srcu_ctl.completed & 0x1;

cnt += sprintf(&page[cnt], "%s%s per-CPU(idx=%d):",
torture_type, TORTURE_FLAG, idx);
for_each_possible_cpu(cpu) {
cnt += sprintf(&page[cnt], " %d(%d,%d)", cpu,
per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[!idx],
per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[idx]);
}
cnt += sprintf(&page[cnt], "\n");
return cnt;
}

static struct rcu_torture_ops srcu_ops = {
.init = srcu_torture_init,
.cleanup = srcu_torture_cleanup,
.readlock = srcu_torture_read_lock,
.readdelay = srcu_read_delay,
.readunlock = srcu_torture_read_unlock,
.completed = srcu_torture_completed,
.deferredfree = rcu_sync_torture_deferred_free,
.sync = srcu_torture_synchronize,
.cb_barrier = NULL,
.stats = srcu_torture_stats,
.name = "srcu"
};

/*
* Definitions for sched torture testing.
*/

static int sched_torture_read_lock(void)
{
preempt_disable();
return 0;
}

static void sched_torture_read_unlock(int idx)
{
preempt_enable();
}

static int sched_torture_completed(void)
{
return 0;
}

static void rcu_sched_torture_deferred_free(struct rcu_torture *p)
{
call_rcu_sched(&p->rtort_rcu, rcu_torture_cb);
}

static void sched_torture_synchronize(void)
{
synchronize_sched();
}

static struct rcu_torture_ops sched_ops = {
.init = rcu_sync_torture_init,
.cleanup = NULL,
.readlock = sched_torture_read_lock,
.readdelay = rcu_read_delay, /* just reuse rcu's version. */
.readunlock = sched_torture_read_unlock,
.completed = sched_torture_completed,
.deferredfree = rcu_sched_torture_deferred_free,
.sync = sched_torture_synchronize,
.cb_barrier = rcu_barrier_sched,
.stats = NULL,
.irqcapable = 1,
.name = "sched"
};

static struct rcu_torture_ops sched_ops_sync = {
.init = rcu_sync_torture_init,
.cleanup = NULL,
.readlock = sched_torture_read_lock,
.readdelay = rcu_read_delay, /* just reuse rcu's version. */
.readunlock = sched_torture_read_unlock,
.completed = sched_torture_completed,
.deferredfree = rcu_sync_torture_deferred_free,
.sync = sched_torture_synchronize,
.cb_barrier = NULL,
.stats = NULL,
.name = "sched_sync"
};

/*
* RCU torture writer kthread. Repeatedly substitutes a new structure
* for that pointed to by rcu_torture_current, freeing the old structure
* after a series of grace periods (the "pipeline").
*/
static int
rcu_torture_writer(void *arg)
{
int i;
long oldbatch = rcu_batches_completed();
struct rcu_torture *rp;
struct rcu_torture *old_rp;
static DEFINE_RCU_RANDOM(rand);

VERBOSE_PRINTK_STRING("rcu_torture_writer task started");
set_user_nice(current, 19);

do {
schedule_timeout_uninterruptible(1);
if ((rp = rcu_torture_alloc()) == NULL)
continue;
rp->rtort_pipe_count = 0;
udelay(rcu_random(&rand) & 0x3ff);
old_rp = rcu_torture_current;
rp->rtort_mbtest = 1;
rcu_assign_pointer(rcu_torture_current, rp);
smp_wmb();
if (old_rp) {
i = old_rp->rtort_pipe_count;
if (i > RCU_TORTURE_PIPE_LEN)
i = RCU_TORTURE_PIPE_LEN;
atomic_inc(&rcu_torture_wcount[i]);
old_rp->rtort_pipe_count++;
cur_ops->deferredfree(old_rp);
}
rcu_torture_current_version++;
oldbatch = cur_ops->completed();
rcu_stutter_wait();
} while (!kthread_should_stop() && !fullstop);
VERBOSE_PRINTK_STRING("rcu_torture_writer task stopping");
while (!kthread_should_stop())
schedule_timeout_uninterruptible(1);
return 0;
}

/*
* RCU torture fake writer kthread. Repeatedly calls sync, with a random
* delay between calls.
*/
static int
rcu_torture_fakewriter(void *arg)
{
DEFINE_RCU_RANDOM(rand);

VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task started");
set_user_nice(current, 19);

do {
schedule_timeout_uninterruptible(1 + rcu_random(&rand)%10);
udelay(rcu_random(&rand) & 0x3ff);
cur_ops->sync();
rcu_stutter_wait();
} while (!kthread_should_stop() && !fullstop);

VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task stopping");
while (!kthread_should_stop())
schedule_timeout_uninterruptible(1);
return 0;
}

/*
* RCU torture reader from timer handler. Dereferences rcu_torture_current,
* incrementing the corresponding element of the pipeline array. The
* counter in the element should never be greater than 1, otherwise, the
* RCU implementation is broken.
*/
static void rcu_torture_timer(unsigned long unused)
{
int idx;
int completed;
static DEFINE_RCU_RANDOM(rand);
static DEFINE_SPINLOCK(rand_lock);
struct rcu_torture *p;
int pipe_count;

idx = cur_ops->readlock();
completed = cur_ops->completed();
p = rcu_dereference(rcu_torture_current);
if (p == NULL) {
/* Leave because rcu_torture_writer is not yet underway */
cur_ops->readunlock(idx);
return;
}
if (p->rtort_mbtest == 0)
atomic_inc(&n_rcu_torture_mberror);
spin_lock(&rand_lock);
cur_ops->readdelay(&rand);
n_rcu_torture_timers++;
spin_unlock(&rand_lock);
preempt_disable();
pipe_count = p->rtort_pipe_count;
if (pipe_count > RCU_TORTURE_PIPE_LEN) {
/* Should not happen, but... */
pipe_count = RCU_TORTURE_PIPE_LEN;
}
++__get_cpu_var(rcu_torture_count)[pipe_count];
completed = cur_ops->completed() - completed;
if (completed > RCU_TORTURE_PIPE_LEN) {
/* Should not happen, but... */
completed = RCU_TORTURE_PIPE_LEN;
}
++__get_cpu_var(rcu_torture_batch)[completed];
preempt_enable();
cur_ops->readunlock(idx);
}

/*
* RCU torture reader kthread. Repeatedly dereferences rcu_torture_current,
* incrementing the corresponding element of the pipeline array. The
* counter in the element should never be greater than 1, otherwise, the
* RCU implementation is broken.
*/
static int
rcu_torture_reader(void *arg)
{
int completed;
int idx;
DEFINE_RCU_RANDOM(rand);
struct rcu_torture *p;
int pipe_count;
struct timer_list t;

VERBOSE_PRINTK_STRING("rcu_torture_reader task started");
set_user_nice(current, 19);
if (irqreader && cur_ops->irqcapable)
setup_timer_on_stack(&t, rcu_torture_timer, 0);

do {
if (irqreader && cur_ops->irqcapable) {
if (!timer_pending(&t))
mod_timer(&t, 1);
}
idx = cur_ops->readlock();
completed = cur_ops->completed();
p = rcu_dereference(rcu_torture_current);
if (p == NULL) {
/* Wait for rcu_torture_writer to get underway */
cur_ops->readunlock(idx);
schedule_timeout_interruptible(HZ);
continue;
}
if (p->rtort_mbtest == 0)
atomic_inc(&n_rcu_torture_mberror);
cur_ops->readdelay(&rand);
preempt_disable();
pipe_count = p->rtort_pipe_count;
if (pipe_count > RCU_TORTURE_PIPE_LEN) {
/* Should not happen, but... */
pipe_count = RCU_TORTURE_PIPE_LEN;
}
++__get_cpu_var(rcu_torture_count)[pipe_count];
completed = cur_ops->completed() - completed;
if (completed > RCU_TORTURE_PIPE_LEN) {
/* Should not happen, but... */
completed = RCU_TORTURE_PIPE_LEN;
}
++__get_cpu_var(rcu_torture_batch)[completed];
preempt_enable();
cur_ops->readunlock(idx);
schedule();
rcu_stutter_wait();
} while (!kthread_should_stop() && !fullstop);
VERBOSE_PRINTK_STRING("rcu_torture_reader task stopping");
if (irqreader && cur_ops->irqcapable)
del_timer_sync(&t);
while (!kthread_should_stop())
schedule_timeout_uninterruptible(1);
return 0;
}

/*
* Create an RCU-torture statistics message in the specified buffer.
*/
static int
rcu_torture_printk(char *page)
{
int cnt = 0;
int cpu;
int i;
long pipesummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
long batchsummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };

for_each_possible_cpu(cpu) {
for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
pipesummary[i] += per_cpu(rcu_torture_count, cpu)[i];
batchsummary[i] += per_cpu(rcu_torture_batch, cpu)[i];
}
}
for (i = RCU_TORTURE_PIPE_LEN - 1; i >= 0; i--) {
if (pipesummary[i] != 0)
break;
}
cnt += sprintf(&page[cnt], "%s%s ", torture_type, TORTURE_FLAG);
cnt += sprintf(&page[cnt],
"rtc: %p ver: %ld tfle: %d rta: %d rtaf: %d rtf: %d "
"rtmbe: %d nt: %ld",
rcu_torture_current,
rcu_torture_current_version,
list_empty(&rcu_torture_freelist),
atomic_read(&n_rcu_torture_alloc),
atomic_read(&n_rcu_torture_alloc_fail),
atomic_read(&n_rcu_torture_free),
atomic_read(&n_rcu_torture_mberror),
n_rcu_torture_timers);
if (atomic_read(&n_rcu_torture_mberror) != 0)
cnt += sprintf(&page[cnt], " !!!");
cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
if (i > 1) {
cnt += sprintf(&page[cnt], "!!! ");
atomic_inc(&n_rcu_torture_error);
WARN_ON_ONCE(1);
}
cnt += sprintf(&page[cnt], "Reader Pipe: ");
for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
cnt += sprintf(&page[cnt], " %ld", pipesummary[i]);
cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
cnt += sprintf(&page[cnt], "Reader Batch: ");
for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
cnt += sprintf(&page[cnt], " %ld", batchsummary[i]);
cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
cnt += sprintf(&page[cnt], "Free-Block Circulation: ");
for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
cnt += sprintf(&page[cnt], " %d",
atomic_read(&rcu_torture_wcount[i]));
}
cnt += sprintf(&page[cnt], "\n");
if (cur_ops->stats)
cnt += cur_ops->stats(&page[cnt]);
return cnt;
}

/*
* Print torture statistics. Caller must ensure that there is only
* one call to this function at a given time!!! This is normally
* accomplished by relying on the module system to only have one copy
* of the module loaded, and then by giving the rcu_torture_stats
* kthread full control (or the init/cleanup functions when rcu_torture_stats
* thread is not running).
*/
static void
rcu_torture_stats_print(void)
{
int cnt;

cnt = rcu_torture_printk(printk_buf);
printk(KERN_ALERT "%s", printk_buf);
}

/*
* Periodically prints torture statistics, if periodic statistics printing
* was specified via the stat_interval module parameter.
*
* No need to worry about fullstop here, since this one doesn't reference
* volatile state or register callbacks.
*/
static int
rcu_torture_stats(void *arg)
{
VERBOSE_PRINTK_STRING("rcu_torture_stats task started");
do {
schedule_timeout_interruptible(stat_interval * HZ);
rcu_torture_stats_print();
} while (!kthread_should_stop());
VERBOSE_PRINTK_STRING("rcu_torture_stats task stopping");
return 0;
}

static int rcu_idle_cpu; /* Force all torture tasks off this CPU */

/* Shuffle tasks such that we allow @rcu_idle_cpu to become idle. A special case
* is when @rcu_idle_cpu = -1, when we allow the tasks to run on all CPUs.
*/
static void rcu_torture_shuffle_tasks(void)
{
cpumask_t tmp_mask;
int i;

cpus_setall(tmp_mask);
get_online_cpus();

/* No point in shuffling if there is only one online CPU (ex: UP) */
if (num_online_cpus() == 1) {
put_online_cpus();
return;
}

if (rcu_idle_cpu != -1)
cpu_clear(rcu_idle_cpu, tmp_mask);

set_cpus_allowed_ptr(current, &tmp_mask);

if (reader_tasks) {
for (i = 0; i < nrealreaders; i++)
if (reader_tasks[i])
set_cpus_allowed_ptr(reader_tasks[i],
&tmp_mask);
}

if (fakewriter_tasks) {
for (i = 0; i < nfakewriters; i++)
if (fakewriter_tasks[i])
set_cpus_allowed_ptr(fakewriter_tasks[i],
&tmp_mask);
}

if (writer_task)
set_cpus_allowed_ptr(writer_task, &tmp_mask);

if (stats_task)
set_cpus_allowed_ptr(stats_task, &tmp_mask);

if (rcu_idle_cpu == -1)
rcu_idle_cpu = num_online_cpus() - 1;
else
rcu_idle_cpu--;

put_online_cpus();
}

/* Shuffle tasks across CPUs, with the intent of allowing each CPU in the
* system to become idle at a time and cut off its timer ticks. This is meant
* to test the support for such tickless idle CPU in RCU.
*/
static int
rcu_torture_shuffle(void *arg)
{
VERBOSE_PRINTK_STRING("rcu_torture_shuffle task started");
do {
schedule_timeout_interruptible(shuffle_interval * HZ);
rcu_torture_shuffle_tasks();
} while (!kthread_should_stop());
VERBOSE_PRINTK_STRING("rcu_torture_shuffle task stopping");
return 0;
}

/* Cause the rcutorture test to "stutter", starting and stopping all
* threads periodically.
*/
static int
rcu_torture_stutter(void *arg)
{
VERBOSE_PRINTK_STRING("rcu_torture_stutter task started");
do {
schedule_timeout_interruptible(stutter * HZ);
stutter_pause_test = 1;
if (!kthread_should_stop())
schedule_timeout_interruptible(stutter * HZ);
stutter_pause_test = 0;
} while (!kthread_should_stop());
VERBOSE_PRINTK_STRING("rcu_torture_stutter task stopping");
return 0;
}

static inline void
rcu_torture_print_module_parms(char *tag)
{
printk(KERN_ALERT "%s" TORTURE_FLAG
"--- %s: nreaders=%d nfakewriters=%d "
"stat_interval=%d verbose=%d test_no_idle_hz=%d "
"shuffle_interval=%d stutter=%d irqreader=%d\n",
torture_type, tag, nrealreaders, nfakewriters,
stat_interval, verbose, test_no_idle_hz, shuffle_interval,
stutter, irqreader);
}

static void
rcu_torture_cleanup(void)
{
int i;

fullstop = 1;
if (stutter_task) {
VERBOSE_PRINTK_STRING("Stopping rcu_torture_stutter task");
kthread_stop(stutter_task);
}
stutter_task = NULL;
if (shuffler_task) {
VERBOSE_PRINTK_STRING("Stopping rcu_torture_shuffle task");
kthread_stop(shuffler_task);
}
shuffler_task = NULL;

if (writer_task) {
VERBOSE_PRINTK_STRING("Stopping rcu_torture_writer task");
kthread_stop(writer_task);
}
writer_task = NULL;

if (reader_tasks) {
for (i = 0; i < nrealreaders; i++) {
if (reader_tasks[i]) {
VERBOSE_PRINTK_STRING(
"Stopping rcu_torture_reader task");
kthread_stop(reader_tasks[i]);
}
reader_tasks[i] = NULL;
}
kfree(reader_tasks);
reader_tasks = NULL;
}
rcu_torture_current = NULL;

if (fakewriter_tasks) {
for (i = 0; i < nfakewriters; i++) {
if (fakewriter_tasks[i]) {
VERBOSE_PRINTK_STRING(
"Stopping rcu_torture_fakewriter task");
kthread_stop(fakewriter_tasks[i]);
}
fakewriter_tasks[i] = NULL;
}
kfree(fakewriter_tasks);
fakewriter_tasks = NULL;
}

if (stats_task) {
VERBOSE_PRINTK_STRING("Stopping rcu_torture_stats task");
kthread_stop(stats_task);
}
stats_task = NULL;

/* Wait for all RCU callbacks to fire. */

if (cur_ops->cb_barrier != NULL)
cur_ops->cb_barrier();

rcu_torture_stats_print(); /* -After- the stats thread is stopped! */

if (cur_ops->cleanup)
cur_ops->cleanup();
if (atomic_read(&n_rcu_torture_error))
rcu_torture_print_module_parms("End of test: FAILURE");
else
rcu_torture_print_module_parms("End of test: SUCCESS");
}

static int __init
rcu_torture_init(void)
{
int i;
int cpu;
int firsterr = 0;
static struct rcu_torture_ops *torture_ops[] =
{ &rcu_ops, &rcu_sync_ops, &rcu_bh_ops, &rcu_bh_sync_ops,
&srcu_ops, &sched_ops, &sched_ops_sync, };

/* Process args and tell the world that the torturer is on the job. */
for (i = 0; i < ARRAY_SIZE(torture_ops); i++) {
cur_ops = torture_ops[i];
if (strcmp(torture_type, cur_ops->name) == 0)
break;
}
if (i == ARRAY_SIZE(torture_ops)) {
printk(KERN_ALERT "rcutorture: invalid torture type: \"%s\"\n",
torture_type);
return (-EINVAL);
}
if (cur_ops->init)
cur_ops->init(); /* no "goto unwind" prior to this point!!! */

if (nreaders >= 0)
nrealreaders = nreaders;
else
nrealreaders = 2 * num_online_cpus();
rcu_torture_print_module_parms("Start of test");
fullstop = 0;

/* Set up the freelist. */

INIT_LIST_HEAD(&rcu_torture_freelist);
for (i = 0; i < ARRAY_SIZE(rcu_tortures); i++) {
rcu_tortures[i].rtort_mbtest = 0;
list_add_tail(&rcu_tortures[i].rtort_free,
&rcu_torture_freelist);
}

/* Initialize the statistics so that each run gets its own numbers. */

rcu_torture_current = NULL;
rcu_torture_current_version = 0;
atomic_set(&n_rcu_torture_alloc, 0);
atomic_set(&n_rcu_torture_alloc_fail, 0);
atomic_set(&n_rcu_torture_free, 0);
atomic_set(&n_rcu_torture_mberror, 0);
atomic_set(&n_rcu_torture_error, 0);
for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
atomic_set(&rcu_torture_wcount[i], 0);
for_each_possible_cpu(cpu) {
for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
per_cpu(rcu_torture_count, cpu)[i] = 0;
per_cpu(rcu_torture_batch, cpu)[i] = 0;
}
}

/* Start up the kthreads. */

VERBOSE_PRINTK_STRING("Creating rcu_torture_writer task");
writer_task = kthread_run(rcu_torture_writer, NULL,
"rcu_torture_writer");
if (IS_ERR(writer_task)) {
firsterr = PTR_ERR(writer_task);
VERBOSE_PRINTK_ERRSTRING("Failed to create writer");
writer_task = NULL;
goto unwind;
}
fakewriter_tasks = kzalloc(nfakewriters * sizeof(fakewriter_tasks[0]),
GFP_KERNEL);
if (fakewriter_tasks == NULL) {
VERBOSE_PRINTK_ERRSTRING("out of memory");
firsterr = -ENOMEM;
goto unwind;
}
for (i = 0; i < nfakewriters; i++) {
VERBOSE_PRINTK_STRING("Creating rcu_torture_fakewriter task");
fakewriter_tasks[i] = kthread_run(rcu_torture_fakewriter, NULL,
"rcu_torture_fakewriter");
if (IS_ERR(fakewriter_tasks[i])) {
firsterr = PTR_ERR(fakewriter_tasks[i]);
VERBOSE_PRINTK_ERRSTRING("Failed to create fakewriter");
fakewriter_tasks[i] = NULL;
goto unwind;
}
}
reader_tasks = kzalloc(nrealreaders * sizeof(reader_tasks[0]),
GFP_KERNEL);
if (reader_tasks == NULL) {
VERBOSE_PRINTK_ERRSTRING("out of memory");
firsterr = -ENOMEM;
goto unwind;
}
for (i = 0; i < nrealreaders; i++) {
VERBOSE_PRINTK_STRING("Creating rcu_torture_reader task");
reader_tasks[i] = kthread_run(rcu_torture_reader, NULL,
"rcu_torture_reader");
if (IS_ERR(reader_tasks[i])) {
firsterr = PTR_ERR(reader_tasks[i]);
VERBOSE_PRINTK_ERRSTRING("Failed to create reader");
reader_tasks[i] = NULL;
goto unwind;
}
}
if (stat_interval > 0) {
VERBOSE_PRINTK_STRING("Creating rcu_torture_stats task");
stats_task = kthread_run(rcu_torture_stats, NULL,
"rcu_torture_stats");
if (IS_ERR(stats_task)) {
firsterr = PTR_ERR(stats_task);
VERBOSE_PRINTK_ERRSTRING("Failed to create stats");
stats_task = NULL;
goto unwind;
}
}
if (test_no_idle_hz) {
rcu_idle_cpu = num_online_cpus() - 1;
/* Create the shuffler thread */
shuffler_task = kthread_run(rcu_torture_shuffle, NULL,
"rcu_torture_shuffle");
if (IS_ERR(shuffler_task)) {
firsterr = PTR_ERR(shuffler_task);
VERBOSE_PRINTK_ERRSTRING("Failed to create shuffler");
shuffler_task = NULL;
goto unwind;
}
}
if (stutter < 0)
stutter = 0;
if (stutter) {
/* Create the stutter thread */
stutter_task = kthread_run(rcu_torture_stutter, NULL,
"rcu_torture_stutter");
if (IS_ERR(stutter_task)) {
firsterr = PTR_ERR(stutter_task);
VERBOSE_PRINTK_ERRSTRING("Failed to create stutter");
stutter_task = NULL;
goto unwind;
}
}
return 0;

unwind:
rcu_torture_cleanup();
return firsterr;
}

module_init(rcu_torture_init);
module_exit(rcu_torture_cleanup);