diff options
Diffstat (limited to 'Documentation/RCU')
| -rw-r--r-- | Documentation/RCU/stallwarn.txt | 7 | ||||
| -rw-r--r-- | Documentation/RCU/torture.txt | 39 | ||||
| -rw-r--r-- | Documentation/RCU/whatisRCU.txt | 6 |
3 files changed, 23 insertions, 29 deletions
diff --git a/Documentation/RCU/stallwarn.txt b/Documentation/RCU/stallwarn.txt index efb9454875ab..0f7fb4298e7e 100644 --- a/Documentation/RCU/stallwarn.txt +++ b/Documentation/RCU/stallwarn.txt @@ -205,6 +205,13 @@ o For !CONFIG_PREEMPT kernels, a CPU looping anywhere in the behavior, you might need to replace some of the cond_resched() calls with calls to cond_resched_rcu_qs(). +o Booting Linux using a console connection that is too slow to + keep up with the boot-time console-message rate. For example, + a 115Kbaud serial console can be -way- too slow to keep up + with boot-time message rates, and will frequently result in + RCU CPU stall warning messages. Especially if you have added + debug printk()s. + o Anything that prevents RCU's grace-period kthreads from running. This can result in the "All QSes seen" console-log message. This message will include information on when the kthread last diff --git a/Documentation/RCU/torture.txt b/Documentation/RCU/torture.txt index dac02a6219b1..118e7c176ce7 100644 --- a/Documentation/RCU/torture.txt +++ b/Documentation/RCU/torture.txt @@ -166,40 +166,27 @@ test_no_idle_hz Whether or not to test the ability of RCU to operate in torture_type The type of RCU to test, with string values as follows: - "rcu": rcu_read_lock(), rcu_read_unlock() and call_rcu(). - - "rcu_sync": rcu_read_lock(), rcu_read_unlock(), and - synchronize_rcu(). - - "rcu_expedited": rcu_read_lock(), rcu_read_unlock(), and - synchronize_rcu_expedited(). + "rcu": rcu_read_lock(), rcu_read_unlock() and call_rcu(), + along with expedited, synchronous, and polling + variants. "rcu_bh": rcu_read_lock_bh(), rcu_read_unlock_bh(), and - call_rcu_bh(). - - "rcu_bh_sync": rcu_read_lock_bh(), rcu_read_unlock_bh(), - and synchronize_rcu_bh(). + call_rcu_bh(), along with expedited and synchronous + variants. - "rcu_bh_expedited": rcu_read_lock_bh(), rcu_read_unlock_bh(), - and synchronize_rcu_bh_expedited(). + "rcu_busted": This tests an intentionally incorrect version + of RCU in order to help test rcutorture itself. "srcu": srcu_read_lock(), srcu_read_unlock() and - call_srcu(). - - "srcu_sync": srcu_read_lock(), srcu_read_unlock() and - synchronize_srcu(). - - "srcu_expedited": srcu_read_lock(), srcu_read_unlock() and - synchronize_srcu_expedited(). + call_srcu(), along with expedited and + synchronous variants. "sched": preempt_disable(), preempt_enable(), and - call_rcu_sched(). - - "sched_sync": preempt_disable(), preempt_enable(), and - synchronize_sched(). + call_rcu_sched(), along with expedited, + synchronous, and polling variants. - "sched_expedited": preempt_disable(), preempt_enable(), and - synchronize_sched_expedited(). + "tasks": voluntary context switch and call_rcu_tasks(), + along with expedited and synchronous variants. Defaults to "rcu". diff --git a/Documentation/RCU/whatisRCU.txt b/Documentation/RCU/whatisRCU.txt index adc2184009c5..dc49c6712b17 100644 --- a/Documentation/RCU/whatisRCU.txt +++ b/Documentation/RCU/whatisRCU.txt @@ -364,7 +364,7 @@ uses of RCU may be found in listRCU.txt, arrayRCU.txt, and NMI-RCU.txt. }; DEFINE_SPINLOCK(foo_mutex); - struct foo *gbl_foo; + struct foo __rcu *gbl_foo; /* * Create a new struct foo that is the same as the one currently @@ -386,7 +386,7 @@ uses of RCU may be found in listRCU.txt, arrayRCU.txt, and NMI-RCU.txt. new_fp = kmalloc(sizeof(*new_fp), GFP_KERNEL); spin_lock(&foo_mutex); - old_fp = gbl_foo; + old_fp = rcu_dereference_protected(gbl_foo, lockdep_is_held(&foo_mutex)); *new_fp = *old_fp; new_fp->a = new_a; rcu_assign_pointer(gbl_foo, new_fp); @@ -487,7 +487,7 @@ The foo_update_a() function might then be written as follows: new_fp = kmalloc(sizeof(*new_fp), GFP_KERNEL); spin_lock(&foo_mutex); - old_fp = gbl_foo; + old_fp = rcu_dereference_protected(gbl_foo, lockdep_is_held(&foo_mutex)); *new_fp = *old_fp; new_fp->a = new_a; rcu_assign_pointer(gbl_foo, new_fp); |