path: root/include/linux
diff options
authorEric W. Biederman <ebiederm@xmission.com>2019-09-14 07:33:34 -0500
committerIngo Molnar <mingo@kernel.org>2019-09-25 17:42:29 +0200
commit3fbd7ee285b2bbc6eebd15a3c8786d9776a402a8 (patch)
treea953a7cc7d724fe39e2c1bd2d218d3dd956c180f /include/linux
parent42fd8baab31f53bed2952485fcf0e92f244c5e55 (diff)
tasks: Add a count of task RCU users
Add a count of the number of RCU users (currently 1) of the task struct so that we can later add the scheduler case and get rid of the very subtle task_rcu_dereference(), and just use rcu_dereference(). As suggested by Oleg have the count overlap rcu_head so that no additional space in task_struct is required. Inspired-by: Linus Torvalds <torvalds@linux-foundation.org> Inspired-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Eric W. Biederman <ebiederm@xmission.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Chris Metcalf <cmetcalf@ezchip.com> Cc: Christoph Lameter <cl@linux.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Kirill Tkhai <tkhai@yandex.ru> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Paul E. McKenney <paulmck@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Russell King - ARM Linux admin <linux@armlinux.org.uk> Cc: Thomas Gleixner <tglx@linutronix.de> Link: https://lkml.kernel.org/r/87woebdplt.fsf_-_@x220.int.ebiederm.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'include/linux')
2 files changed, 5 insertions, 1 deletions
diff --git a/include/linux/sched.h b/include/linux/sched.h
index e2e91960d79f..8e43e54a02c7 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1147,7 +1147,10 @@ struct task_struct {
struct tlbflush_unmap_batch tlb_ubc;
- struct rcu_head rcu;
+ union {
+ refcount_t rcu_users;
+ struct rcu_head rcu;
+ };
/* Cache last used pipe for splice(): */
struct pipe_inode_info *splice_pipe;
diff --git a/include/linux/sched/task.h b/include/linux/sched/task.h
index 3d90ed8f75f0..153a683646ac 100644
--- a/include/linux/sched/task.h
+++ b/include/linux/sched/task.h
@@ -120,6 +120,7 @@ static inline void put_task_struct(struct task_struct *t)
struct task_struct *task_rcu_dereference(struct task_struct **ptask);
+void put_task_struct_rcu_user(struct task_struct *task);
extern int arch_task_struct_size __read_mostly;

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