From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752328AbdCPL0j (ORCPT ); Thu, 16 Mar 2017 07:26:39 -0400 Received: from terminus.zytor.com ([65.50.211.136]:44828 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752300AbdCPL0h (ORCPT ); Thu, 16 Mar 2017 07:26:37 -0400 Date: Thu, 16 Mar 2017 04:25:46 -0700 From: "tip-bot for J. R. Okajima" Message-ID: Cc: torvalds@linux-foundation.org, akpm@linux-foundation.org, tglx@linutronix.de, paulmck@linux.vnet.ibm.com, linux-kernel@vger.kernel.org, hpa@zytor.com, mingo@kernel.org, hooanon05g@gmail.com, peterz@infradead.org Reply-To: linux-kernel@vger.kernel.org, hpa@zytor.com, mingo@kernel.org, torvalds@linux-foundation.org, akpm@linux-foundation.org, tglx@linutronix.de, paulmck@linux.vnet.ibm.com, hooanon05g@gmail.com, peterz@infradead.org In-Reply-To: <1486053497-9948-3-git-send-email-hooanon05g@gmail.com> References: <1486053497-9948-3-git-send-email-hooanon05g@gmail.com> To: linux-tip-commits@vger.kernel.org Subject: [tip:locking/core] locking/lockdep: Add new check to lock_downgrade() Git-Commit-ID: 6419c4af777a773a45a1b1af735de0fcd9a7dcc7 X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: 6419c4af777a773a45a1b1af735de0fcd9a7dcc7 Gitweb: http://git.kernel.org/tip/6419c4af777a773a45a1b1af735de0fcd9a7dcc7 Author: J. R. Okajima AuthorDate: Fri, 3 Feb 2017 01:38:17 +0900 Committer: Ingo Molnar CommitDate: Thu, 16 Mar 2017 09:57:07 +0100 locking/lockdep: Add new check to lock_downgrade() Commit: f8319483f57f ("locking/lockdep: Provide a type check for lock_is_held") didn't fully cover rwsems as downgrade_write() was left out. Introduce lock_downgrade() and use it to add new checks. See-also: http://marc.info/?l=linux-kernel&m=148581164003149&w=2 Originally-written-by: Peter Zijlstra Signed-off-by: J. R. Okajima Signed-off-by: Peter Zijlstra (Intel) Cc: Andrew Morton Cc: Linus Torvalds Cc: Paul E. McKenney Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/1486053497-9948-3-git-send-email-hooanon05g@gmail.com [ Rewrote the changelog. ] Signed-off-by: Ingo Molnar --- include/linux/lockdep.h | 3 +++ kernel/locking/lockdep.c | 55 ++++++++++++++++++++++++++++++++++++++++++++++++ kernel/locking/rwsem.c | 6 ++---- 3 files changed, 60 insertions(+), 4 deletions(-) diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h index 1e327bb..fffe49f 100644 --- a/include/linux/lockdep.h +++ b/include/linux/lockdep.h @@ -361,6 +361,8 @@ static inline void lock_set_subclass(struct lockdep_map *lock, lock_set_class(lock, lock->name, lock->key, subclass, ip); } +extern void lock_downgrade(struct lockdep_map *lock, unsigned long ip); + extern void lockdep_set_current_reclaim_state(gfp_t gfp_mask); extern void lockdep_clear_current_reclaim_state(void); extern void lockdep_trace_alloc(gfp_t mask); @@ -411,6 +413,7 @@ static inline void lockdep_on(void) # define lock_acquire(l, s, t, r, c, n, i) do { } while (0) # define lock_release(l, n, i) do { } while (0) +# define lock_downgrade(l, i) do { } while (0) # define lock_set_class(l, n, k, s, i) do { } while (0) # define lock_set_subclass(l, s, i) do { } while (0) # define lockdep_set_current_reclaim_state(g) do { } while (0) diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c index da79548..b1a1cef 100644 --- a/kernel/locking/lockdep.c +++ b/kernel/locking/lockdep.c @@ -3533,6 +3533,44 @@ __lock_set_class(struct lockdep_map *lock, const char *name, return 1; } +static int __lock_downgrade(struct lockdep_map *lock, unsigned long ip) +{ + struct task_struct *curr = current; + struct held_lock *hlock; + unsigned int depth; + int i; + + depth = curr->lockdep_depth; + /* + * This function is about (re)setting the class of a held lock, + * yet we're not actually holding any locks. Naughty user! + */ + if (DEBUG_LOCKS_WARN_ON(!depth)) + return 0; + + hlock = find_held_lock(curr, lock, depth, &i); + if (!hlock) + return print_unlock_imbalance_bug(curr, lock, ip); + + curr->lockdep_depth = i; + curr->curr_chain_key = hlock->prev_chain_key; + + WARN(hlock->read, "downgrading a read lock"); + hlock->read = 1; + hlock->acquire_ip = ip; + + if (reacquire_held_locks(curr, depth, i)) + return 0; + + /* + * I took it apart and put it back together again, except now I have + * these 'spare' parts.. where shall I put them. + */ + if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth)) + return 0; + return 1; +} + /* * Remove the lock to the list of currently held locks - this gets * called on mutex_unlock()/spin_unlock*() (or on a failed @@ -3759,6 +3797,23 @@ void lock_set_class(struct lockdep_map *lock, const char *name, } EXPORT_SYMBOL_GPL(lock_set_class); +void lock_downgrade(struct lockdep_map *lock, unsigned long ip) +{ + unsigned long flags; + + if (unlikely(current->lockdep_recursion)) + return; + + raw_local_irq_save(flags); + current->lockdep_recursion = 1; + check_flags(flags); + if (__lock_downgrade(lock, ip)) + check_chain_key(current); + current->lockdep_recursion = 0; + raw_local_irq_restore(flags); +} +EXPORT_SYMBOL_GPL(lock_downgrade); + /* * We are not always called with irqs disabled - do that here, * and also avoid lockdep recursion: diff --git a/kernel/locking/rwsem.c b/kernel/locking/rwsem.c index 90a74cc..4d48b1c 100644 --- a/kernel/locking/rwsem.c +++ b/kernel/locking/rwsem.c @@ -124,10 +124,8 @@ EXPORT_SYMBOL(up_write); */ void downgrade_write(struct rw_semaphore *sem) { - /* - * lockdep: a downgraded write will live on as a write - * dependency. - */ + lock_downgrade(&sem->dep_map, _RET_IP_); + rwsem_set_reader_owned(sem); __downgrade_write(sem); }