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 <pet...@infradead.org> > 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] [<ffffffff81491238>] ? _raw_spin_unlock_irqrestore+0x6c/0x7a > [ 82.172701] [<ffffffff8148fd3f>] schedule+0x64/0x66 > [ 82.172704] [<ffffffff8148ec6b>] schedule_timeout+0x27/0xd0 > [ 82.172708] [<ffffffff81043c0c>] ? unpin_current_cpu+0x1a/0x6c > [ 82.172713] [<ffffffff8106e491>] ? migrate_enable+0x12f/0x141 > [ 82.172716] [<ffffffff8148fbbd>] wait_for_common+0xbb/0x11f > [ 82.172719] [<ffffffff810709f2>] ? try_to_wake_up+0x182/0x182 > [ 82.172722] [<ffffffff8148fc96>] > wait_for_completion_interruptible+0x1d/0x2e > [ 82.172726] [<ffffffff811debfd>] crypto_wait_for_test+0x49/0x6b > [ 82.172728] [<ffffffff811ded32>] crypto_register_alg+0x53/0x5a > [ 82.172730] [<ffffffff811ded6c>] crypto_register_algs+0x33/0x72 > [ 82.172734] [<ffffffff81ad7686>] ? aes_init+0x12/0x12 > [ 82.172737] [<ffffffff81ad76ea>] aesni_init+0x64/0x66 > [ 82.172741] [<ffffffff81000318>] do_one_initcall+0x7f/0x13b > [ 82.172744] [<ffffffff81ac4d34>] kernel_init+0x199/0x22c > [ 82.172747] [<ffffffff81ac44ef>] ? loglevel+0x31/0x31 > [ 82.172752] [<ffffffff814987c4>] kernel_thread_helper+0x4/0x10 > [ 82.172755] [<ffffffff81491574>] ? retint_restore_args+0x13/0x13 > [ 82.172759] [<ffffffff81ac4b9b>] ? start_kernel+0x3ca/0x3ca > [ 82.172761] [<ffffffff814987c0>] ? 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] [<ffffffff8148fd3f>] schedule+0x64/0x66 > [ 82.174201] [<ffffffff8148ec6b>] schedule_timeout+0x27/0xd0 > [ 82.174204] [<ffffffff81043c0c>] ? unpin_current_cpu+0x1a/0x6c > [ 82.174206] [<ffffffff8106e491>] ? migrate_enable+0x12f/0x141 > [ 82.174209] [<ffffffff8148fbbd>] wait_for_common+0xbb/0x11f > [ 82.174212] [<ffffffff810709f2>] ? try_to_wake_up+0x182/0x182 > [ 82.174215] [<ffffffff8148fc96>] > wait_for_completion_interruptible+0x1d/0x2e > [ 82.174218] [<ffffffff811e4883>] cryptomgr_notify+0x280/0x385 > [ 82.174221] [<ffffffff814943de>] notifier_call_chain+0x6b/0x98 > [ 82.174224] [<ffffffff8108a11c>] ? rt_down_read+0x10/0x12 > [ 82.174227] [<ffffffff810677cd>] __blocking_notifier_call_chain+0x70/0x8d > [ 82.174230] [<ffffffff810677fe>] blocking_notifier_call_chain+0x14/0x16 > [ 82.174234] [<ffffffff811dd272>] crypto_probing_notify+0x24/0x50 > [ 82.174236] [<ffffffff811dd7a1>] crypto_alg_mod_lookup+0x3e/0x74 > [ 82.174238] [<ffffffff811dd949>] crypto_alloc_base+0x36/0x8f > [ 82.174241] [<ffffffff811e9408>] cryptd_alloc_ablkcipher+0x6e/0xb5 > [ 82.174243] [<ffffffff811dd591>] ? kzalloc.clone.5+0xe/0x10 > [ 82.174246] [<ffffffff8103085d>] ablk_init_common+0x1d/0x38 > [ 82.174249] [<ffffffff8103852a>] ablk_ecb_init+0x15/0x17 > [ 82.174251] [<ffffffff811dd8c6>] __crypto_alloc_tfm+0xc7/0x114 > [ 82.174254] [<ffffffff811e0caa>] ? crypto_lookup_skcipher+0x1f/0xe4 > [ 82.174256] [<ffffffff811e0dcf>] crypto_alloc_ablkcipher+0x60/0xa5 > [ 82.174258] [<ffffffff811e5bde>] alg_test_skcipher+0x24/0x9b > [ 82.174261] [<ffffffff8106d96d>] ? finish_task_switch+0x3f/0xfa > [ 82.174263] [<ffffffff811e6b8e>] alg_test+0x16f/0x1d7 > [ 82.174267] [<ffffffff811e45ac>] ? cryptomgr_probe+0xac/0xac > [ 82.174269] [<ffffffff811e45d8>] cryptomgr_test+0x2c/0x47 > [ 82.174272] [<ffffffff81061161>] kthread+0x7e/0x86 > [ 82.174275] [<ffffffff8106d9dd>] ? finish_task_switch+0xaf/0xfa > [ 82.174278] [<ffffffff814987c4>] kernel_thread_helper+0x4/0x10 > [ 82.174281] [<ffffffff81491574>] ? retint_restore_args+0x13/0x13 > [ 82.174284] [<ffffffff810610e3>] ? __init_kthread_worker+0x8c/0x8c > [ 82.174287] [<ffffffff814987c0>] ? 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] [<ffffffff8148fd3f>] schedule+0x64/0x66 > [ 82.174344] [<ffffffff814901ad>] __rt_mutex_slowlock+0x85/0xbe > [ 82.174347] [<ffffffff814902d2>] rt_mutex_slowlock+0xec/0x159 > [ 82.174351] [<ffffffff81089c4d>] rt_mutex_fastlock.clone.8+0x29/0x2f > [ 82.174353] [<ffffffff81490372>] rt_mutex_lock+0x33/0x37 > [ 82.174356] [<ffffffff8108a0f2>] __rt_down_read+0x50/0x5a > [ 82.174358] [<ffffffff8108a11c>] ? rt_down_read+0x10/0x12 > [ 82.174360] [<ffffffff8108a11c>] rt_down_read+0x10/0x12 > [ 82.174363] [<ffffffff810677b5>] __blocking_notifier_call_chain+0x58/0x8d > [ 82.174366] [<ffffffff810677fe>] blocking_notifier_call_chain+0x14/0x16 > [ 82.174369] [<ffffffff811dd272>] crypto_probing_notify+0x24/0x50 > [ 82.174372] [<ffffffff811debd6>] crypto_wait_for_test+0x22/0x6b > [ 82.174374] [<ffffffff811decd3>] crypto_register_instance+0xb4/0xc0 > [ 82.174377] [<ffffffff811e9b76>] cryptd_create+0x378/0x3b6 > [ 82.174379] [<ffffffff811de512>] ? __crypto_lookup_template+0x5b/0x63 > [ 82.174382] [<ffffffff811e4545>] cryptomgr_probe+0x45/0xac > [ 82.174385] [<ffffffff811e4500>] ? crypto_alloc_pcomp+0x1b/0x1b > [ 82.174388] [<ffffffff81061161>] kthread+0x7e/0x86 > [ 82.174391] [<ffffffff8106d9dd>] ? finish_task_switch+0xaf/0xfa > [ 82.174394] [<ffffffff814987c4>] kernel_thread_helper+0x4/0x10 > [ 82.174398] [<ffffffff81491574>] ? retint_restore_args+0x13/0x13 > [ 82.174401] [<ffffffff810610e3>] ? __init_kthread_worker+0x8c/0x8c > [ 82.174403] [<ffffffff814987c0>] ? 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 <pet...@infradead.org> > Signed-off-by: Thomas Gleixner <t...@linutronix.de> > --- > 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 > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/