linux-kernel - [PATCH 2/3] kernel,cred,kvm,security - removing superfluous rcu_read_lock

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Date:	Mon,  1 Nov 2010 20:15:08 +0100
From:	Jiri Olsa <jolsa@...hat.com>
To:	dhowells@...hat.com, lizf@...fujitsu.com, paul.moore@...com,
	johannes@...solutions.net, dipankar@...ibm.com
Cc:	linux-kernel@...r.kernel.org,
	containers@...ts.linux-foundation.org, kvm@...r.kernel.org,
	Jiri Olsa <jolsa@...hat.com>
Subject: [PATCH 2/3] kernel,cred,kvm,security - removing superfluous rcu_read_lock_held check

hi,
the rcu_dereference_check is defined as

	#define rcu_dereference_check(p, c) \
	   __rcu_dereference_check((p), rcu_read_lock_held() || (c), __rcu)

so the caller does not need to specify rcu_read_lock_held() condition.

wbr,
jirka


Signed-off-by: Jiri Olsa <jolsa@...hat.com>
---
 include/linux/cred.h     |    1 -
 include/linux/fdtable.h  |    1 -
 include/linux/kvm_host.h |    1 -
 kernel/exit.c            |    1 -
 kernel/pid.c             |    1 -
 kernel/rcutorture.c      |    2 --
 security/keys/keyring.c  |    1 -
 7 files changed, 0 insertions(+), 8 deletions(-)

diff --git a/include/linux/cred.h b/include/linux/cred.h
index 4aaeab3..a6b9afc 100644
--- a/include/linux/cred.h
+++ b/include/linux/cred.h
@@ -283,7 +283,6 @@ static inline void put_cred(const struct cred *_cred)
 	({								\
 		const struct task_struct *__t = (task);			\
 		rcu_dereference_check(__t->real_cred,			\
-				      rcu_read_lock_held() ||		\
 				      task_is_dead(__t));		\
 	})
 
diff --git a/include/linux/fdtable.h b/include/linux/fdtable.h
index 133c0ba..df7e3cf 100644
--- a/include/linux/fdtable.h
+++ b/include/linux/fdtable.h
@@ -60,7 +60,6 @@ struct files_struct {
 
 #define rcu_dereference_check_fdtable(files, fdtfd) \
 	(rcu_dereference_check((fdtfd), \
-			       rcu_read_lock_held() || \
 			       lockdep_is_held(&(files)->file_lock) || \
 			       atomic_read(&(files)->count) == 1 || \
 			       rcu_my_thread_group_empty()))
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index a055742..a90a7e3 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -256,7 +256,6 @@ void kvm_put_kvm(struct kvm *kvm);
 static inline struct kvm_memslots *kvm_memslots(struct kvm *kvm)
 {
 	return rcu_dereference_check(kvm->memslots,
-			srcu_read_lock_held(&kvm->srcu)
 			|| lockdep_is_held(&kvm->slots_lock));
 }
 
diff --git a/kernel/exit.c b/kernel/exit.c
index b194feb..f753342 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -85,7 +85,6 @@ static void __exit_signal(struct task_struct *tsk)
 	struct tty_struct *uninitialized_var(tty);
 
 	sighand = rcu_dereference_check(tsk->sighand,
-					rcu_read_lock_held() ||
 					lockdep_tasklist_lock_is_held());
 	spin_lock(&sighand->siglock);
 
diff --git a/kernel/pid.c b/kernel/pid.c
index 39b65b6..c02adda 100644
--- a/kernel/pid.c
+++ b/kernel/pid.c
@@ -402,7 +402,6 @@ struct task_struct *pid_task(struct pid *pid, enum pid_type type)
 	if (pid) {
 		struct hlist_node *first;
 		first = rcu_dereference_check(hlist_first_rcu(&pid->tasks[type]),
-					      rcu_read_lock_held() ||
 					      lockdep_tasklist_lock_is_held());
 		if (first)
 			result = hlist_entry(first, struct task_struct, pids[(type)].node);
diff --git a/kernel/rcutorture.c b/kernel/rcutorture.c
index 9d8e8fb..0956a73 100644
--- a/kernel/rcutorture.c
+++ b/kernel/rcutorture.c
@@ -807,7 +807,6 @@ static void rcu_torture_timer(unsigned long unused)
 	idx = cur_ops->readlock();
 	completed = cur_ops->completed();
 	p = rcu_dereference_check(rcu_torture_current,
-				  rcu_read_lock_held() ||
 				  rcu_read_lock_bh_held() ||
 				  rcu_read_lock_sched_held() ||
 				  srcu_read_lock_held(&srcu_ctl));
@@ -868,7 +867,6 @@ rcu_torture_reader(void *arg)
 		idx = cur_ops->readlock();
 		completed = cur_ops->completed();
 		p = rcu_dereference_check(rcu_torture_current,
-					  rcu_read_lock_held() ||
 					  rcu_read_lock_bh_held() ||
 					  rcu_read_lock_sched_held() ||
 					  srcu_read_lock_held(&srcu_ctl));
diff --git a/security/keys/keyring.c b/security/keys/keyring.c
index d37f713..73c23f2 100644
--- a/security/keys/keyring.c
+++ b/security/keys/keyring.c
@@ -157,7 +157,6 @@ static void keyring_destroy(struct key *keyring)
 	}
 
 	klist = rcu_dereference_check(keyring->payload.subscriptions,
-				      rcu_read_lock_held() ||
 				      atomic_read(&keyring->usage) == 0);
 	if (klist) {
 		for (loop = klist->nkeys - 1; loop >= 0; loop--)
-- 
1.7.1

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