From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752653Ab3DLCxg (ORCPT ); Thu, 11 Apr 2013 22:53:36 -0400 Received: from cn.fujitsu.com ([222.73.24.84]:2773 "EHLO song.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1751736Ab3DLCxe (ORCPT ); Thu, 11 Apr 2013 22:53:34 -0400 X-IronPort-AV: E=Sophos;i="4.87,460,1363104000"; d="scan'208";a="7040372" Message-ID: <516777DB.2080109@cn.fujitsu.com> Date: Fri, 12 Apr 2013 10:56:27 +0800 From: Lai Jiangshan User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.9) Gecko/20100921 Fedora/3.1.4-1.fc14 Thunderbird/3.1.4 MIME-Version: 1.0 To: Sebastian Andrzej Siewior CC: "Paul E. McKenney" , linux-kernel@vger.kernel.org, tglx@linutronix.de, Peter Zijlstra , Herbert Xu Subject: Re: [PATCH 2/3] kernel/SRCU: provide a static initializer References: <1363702606-31586-1-git-send-email-bigeasy@linutronix.de> <1363702606-31586-2-git-send-email-bigeasy@linutronix.de> <515E7B79.2020707@cn.fujitsu.com> <516295E7.70200@linutronix.de> <51636A64.5050002@cn.fujitsu.com> <20130411170450.GA27081@linutronix.de> In-Reply-To: <20130411170450.GA27081@linutronix.de> X-MIMETrack: Itemize by SMTP Server on mailserver/fnst(Release 8.5.3|September 15, 2011) at 2013/04/12 10:52:11, Serialize by Router on mailserver/fnst(Release 8.5.3|September 15, 2011) at 2013/04/12 10:52:12, Serialize complete at 2013/04/12 10:52:12 Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 04/12/2013 01:04 AM, Sebastian Andrzej Siewior wrote: > * Lai Jiangshan | 2013-04-09 09:09:56 [+0800]: > >> If the percpu array can be defined in __SRCU_STRUCT_INIT(), >> I'm happy to expose it. but it is not currently. > > I have no idea how to achieve this. > >> Why crypto can't use boot time initialization? > > It would require something like this: > --- linux-stable.orig/crypto/Kconfig > +++ linux-stable/crypto/Kconfig > @@ -13,7 +13,7 @@ source "crypto/async_tx/Kconfig" > # Cryptographic API Configuration > # > menuconfig CRYPTO > - tristate "Cryptographic API" > + bool "Cryptographic API" > help > This option provides the core Cryptographic API. Why convert to "bool"? srcu_init_notifier_head() can be called in module-load-time. > > --- linux-stable.orig/crypto/api.c > +++ linux-stable/crypto/api.c > @@ -34,6 +34,13 @@ EXPORT_SYMBOL_GPL(crypto_alg_sem); > struct srcu_notifier_head crypto_chain; > EXPORT_SYMBOL_GPL(crypto_chain); > > +static int __init crypto_api_init(void) > +{ > + srcu_init_notifier_head(&crypto_chain); > + return 0; > +} > +core_initcall(crypto_api_init); > + > static inline struct crypto_alg *crypto_alg_get(struct crypto_alg *alg) > { > atomic_inc(&alg->cra_refcnt); And again, why crypto can't use boot time nor module-load-time initialization? > > and there is no need for this. > >>> Do you have any idea how I could get it done without this? Do you want >>> to move/merge header files? >> >> if crypto has to use static initialization, I will find out some way >> or use your patch. > > The crypto would like this: > > Subject: crypto: Convert crypto notifier chain to SRCU > From: Peter Zijlstra > Date: Fri, 05 Oct 2012 09:03:24 +0100 > > The crypto notifier deadlocks on RT. Though this can be a real deadlock > on mainline as well due to fifo fair rwsems. > > The involved parties here are: > > [ 82.172678] swapper/0 S 0000000000000001 0 1 0 0x00000000 > [ 82.172682] ffff88042f18fcf0 0000000000000046 ffff88042f18fc80 ffffffff81491238 > [ 82.172685] 0000000000011cc0 0000000000011cc0 ffff88042f18c040 ffff88042f18ffd8 > [ 82.172688] 0000000000011cc0 0000000000011cc0 ffff88042f18ffd8 0000000000011cc0 > [ 82.172689] Call Trace: > [ 82.172697] [] ? _raw_spin_unlock_irqrestore+0x6c/0x7a > [ 82.172701] [] schedule+0x64/0x66 > [ 82.172704] [] schedule_timeout+0x27/0xd0 > [ 82.172708] [] ? unpin_current_cpu+0x1a/0x6c > [ 82.172713] [] ? migrate_enable+0x12f/0x141 > [ 82.172716] [] wait_for_common+0xbb/0x11f > [ 82.172719] [] ? try_to_wake_up+0x182/0x182 > [ 82.172722] [] wait_for_completion_interruptible+0x1d/0x2e > [ 82.172726] [] crypto_wait_for_test+0x49/0x6b > [ 82.172728] [] crypto_register_alg+0x53/0x5a > [ 82.172730] [] crypto_register_algs+0x33/0x72 > [ 82.172734] [] ? aes_init+0x12/0x12 > [ 82.172737] [] aesni_init+0x64/0x66 > [ 82.172741] [] do_one_initcall+0x7f/0x13b > [ 82.172744] [] kernel_init+0x199/0x22c > [ 82.172747] [] ? loglevel+0x31/0x31 > [ 82.172752] [] kernel_thread_helper+0x4/0x10 > [ 82.172755] [] ? retint_restore_args+0x13/0x13 > [ 82.172759] [] ? start_kernel+0x3ca/0x3ca > [ 82.172761] [] ? gs_change+0x13/0x13 > > [ 82.174186] cryptomgr_test S 0000000000000001 0 41 2 0x00000000 > [ 82.174189] ffff88042c971980 0000000000000046 ffffffff81d74830 0000000000000292 > [ 82.174192] 0000000000011cc0 0000000000011cc0 ffff88042c96eb80 ffff88042c971fd8 > [ 82.174195] 0000000000011cc0 0000000000011cc0 ffff88042c971fd8 0000000000011cc0 > [ 82.174195] Call Trace: > [ 82.174198] [] schedule+0x64/0x66 > [ 82.174201] [] schedule_timeout+0x27/0xd0 > [ 82.174204] [] ? unpin_current_cpu+0x1a/0x6c > [ 82.174206] [] ? migrate_enable+0x12f/0x141 > [ 82.174209] [] wait_for_common+0xbb/0x11f > [ 82.174212] [] ? try_to_wake_up+0x182/0x182 > [ 82.174215] [] wait_for_completion_interruptible+0x1d/0x2e > [ 82.174218] [] cryptomgr_notify+0x280/0x385 > [ 82.174221] [] notifier_call_chain+0x6b/0x98 > [ 82.174224] [] ? rt_down_read+0x10/0x12 > [ 82.174227] [] __blocking_notifier_call_chain+0x70/0x8d > [ 82.174230] [] blocking_notifier_call_chain+0x14/0x16 > [ 82.174234] [] crypto_probing_notify+0x24/0x50 > [ 82.174236] [] crypto_alg_mod_lookup+0x3e/0x74 > [ 82.174238] [] crypto_alloc_base+0x36/0x8f > [ 82.174241] [] cryptd_alloc_ablkcipher+0x6e/0xb5 > [ 82.174243] [] ? kzalloc.clone.5+0xe/0x10 > [ 82.174246] [] ablk_init_common+0x1d/0x38 > [ 82.174249] [] ablk_ecb_init+0x15/0x17 > [ 82.174251] [] __crypto_alloc_tfm+0xc7/0x114 > [ 82.174254] [] ? crypto_lookup_skcipher+0x1f/0xe4 > [ 82.174256] [] crypto_alloc_ablkcipher+0x60/0xa5 > [ 82.174258] [] alg_test_skcipher+0x24/0x9b > [ 82.174261] [] ? finish_task_switch+0x3f/0xfa > [ 82.174263] [] alg_test+0x16f/0x1d7 > [ 82.174267] [] ? cryptomgr_probe+0xac/0xac > [ 82.174269] [] cryptomgr_test+0x2c/0x47 > [ 82.174272] [] kthread+0x7e/0x86 > [ 82.174275] [] ? finish_task_switch+0xaf/0xfa > [ 82.174278] [] kernel_thread_helper+0x4/0x10 > [ 82.174281] [] ? retint_restore_args+0x13/0x13 > [ 82.174284] [] ? __init_kthread_worker+0x8c/0x8c > [ 82.174287] [] ? gs_change+0x13/0x13 > > [ 82.174329] cryptomgr_probe D 0000000000000002 0 47 2 0x00000000 > [ 82.174332] ffff88042c991b70 0000000000000046 ffff88042c991bb0 0000000000000006 > [ 82.174335] 0000000000011cc0 0000000000011cc0 ffff88042c98ed00 ffff88042c991fd8 > [ 82.174338] 0000000000011cc0 0000000000011cc0 ffff88042c991fd8 0000000000011cc0 > [ 82.174338] Call Trace: > [ 82.174342] [] schedule+0x64/0x66 > [ 82.174344] [] __rt_mutex_slowlock+0x85/0xbe > [ 82.174347] [] rt_mutex_slowlock+0xec/0x159 > [ 82.174351] [] rt_mutex_fastlock.clone.8+0x29/0x2f > [ 82.174353] [] rt_mutex_lock+0x33/0x37 > [ 82.174356] [] __rt_down_read+0x50/0x5a > [ 82.174358] [] ? rt_down_read+0x10/0x12 > [ 82.174360] [] rt_down_read+0x10/0x12 > [ 82.174363] [] __blocking_notifier_call_chain+0x58/0x8d > [ 82.174366] [] blocking_notifier_call_chain+0x14/0x16 > [ 82.174369] [] crypto_probing_notify+0x24/0x50 > [ 82.174372] [] crypto_wait_for_test+0x22/0x6b > [ 82.174374] [] crypto_register_instance+0xb4/0xc0 > [ 82.174377] [] cryptd_create+0x378/0x3b6 > [ 82.174379] [] ? __crypto_lookup_template+0x5b/0x63 > [ 82.174382] [] cryptomgr_probe+0x45/0xac > [ 82.174385] [] ? crypto_alloc_pcomp+0x1b/0x1b > [ 82.174388] [] kthread+0x7e/0x86 > [ 82.174391] [] ? finish_task_switch+0xaf/0xfa > [ 82.174394] [] kernel_thread_helper+0x4/0x10 > [ 82.174398] [] ? retint_restore_args+0x13/0x13 > [ 82.174401] [] ? __init_kthread_worker+0x8c/0x8c > [ 82.174403] [] ? gs_change+0x13/0x13 > > cryptomgr_test spawns the cryptomgr_probe thread from the notifier > call. The probe thread fires the same notifier as the test thread and > deadlocks on the rwsem on RT. > > Now this is a potential deadlock in mainline as well, because we have > fifo fair rwsems. If another thread blocks with a down_write() on the > notifier chain before the probe thread issues the down_read() it will > block the probe thread and the whole party is dead locked. > > Signed-off-by: Peter Zijlstra > Signed-off-by: Thomas Gleixner > --- > crypto/algapi.c | 4 ++-- > crypto/api.c | 6 +++--- > crypto/internal.h | 4 ++-- > 3 files changed, 7 insertions(+), 7 deletions(-) > > --- a/crypto/algapi.c > +++ b/crypto/algapi.c > @@ -683,13 +683,13 @@ EXPORT_SYMBOL_GPL(crypto_spawn_tfm2); > > int crypto_register_notifier(struct notifier_block *nb) > { > - return blocking_notifier_chain_register(&crypto_chain, nb); > + return srcu_notifier_chain_register(&crypto_chain, nb); > } > EXPORT_SYMBOL_GPL(crypto_register_notifier); > > int crypto_unregister_notifier(struct notifier_block *nb) > { > - return blocking_notifier_chain_unregister(&crypto_chain, nb); > + return srcu_notifier_chain_unregister(&crypto_chain, nb); > } > EXPORT_SYMBOL_GPL(crypto_unregister_notifier); > > --- a/crypto/api.c > +++ b/crypto/api.c > @@ -31,7 +31,7 @@ EXPORT_SYMBOL_GPL(crypto_alg_list); > DECLARE_RWSEM(crypto_alg_sem); > EXPORT_SYMBOL_GPL(crypto_alg_sem); > > -BLOCKING_NOTIFIER_HEAD(crypto_chain); > +SRCU_NOTIFIER_HEAD(crypto_chain); > EXPORT_SYMBOL_GPL(crypto_chain); > > static inline struct crypto_alg *crypto_alg_get(struct crypto_alg *alg) > @@ -237,10 +237,10 @@ int crypto_probing_notify(unsigned long > { > int ok; > > - ok = blocking_notifier_call_chain(&crypto_chain, val, v); > + ok = srcu_notifier_call_chain(&crypto_chain, val, v); > if (ok == NOTIFY_DONE) { > request_module("cryptomgr"); > - ok = blocking_notifier_call_chain(&crypto_chain, val, v); > + ok = srcu_notifier_call_chain(&crypto_chain, val, v); > } > > return ok; > --- a/crypto/internal.h > +++ b/crypto/internal.h > @@ -48,7 +48,7 @@ struct crypto_larval { > > extern struct list_head crypto_alg_list; > extern struct rw_semaphore crypto_alg_sem; > -extern struct blocking_notifier_head crypto_chain; > +extern struct srcu_notifier_head crypto_chain; > > #ifdef CONFIG_PROC_FS > void __init crypto_init_proc(void); > @@ -136,7 +136,7 @@ static inline int crypto_is_moribund(str > > static inline void crypto_notify(unsigned long val, void *v) > { > - blocking_notifier_call_chain(&crypto_chain, val, v); > + srcu_notifier_call_chain(&crypto_chain, val, v); > } > > #endif /* _CRYPTO_INTERNAL_H */ > >> Thanks, >> Lai > > Sebastian >