Subject: [PATCH tip/core/rcu 0/21] v6 add lockdep-based diagnostics to rcu_dereference()
Date: Tuesday 23rd February 2010 01:04:35 UTC (over 6 years ago)
Hello! This patch series adds lockdep-based checking to the rcu_dereference() primitive in order to flag misuses of RCU. The first four patches put the RCU infrastructure in place, the next eight use this infrastructure in the net, sched, vfs, radix-tree, idr, and security subsystems, and patch 13 documents how to use the new lockdep-checked rcu_dereference() primitives. The remaining eight patches are other changes that also need to be applied, including some relatively urgent RCU_STALL patches. The new (and default-disabled) CONFIG_PROVE_RCU makes this safe to include in tip/core/rcu -- unlike v2 and earlier, your system won't complain about RCU misuse unless you ask it to. There are still several situations that trigger on systems I have access to (and I have email out on a couple of them), some of the remaining will be triggered only by hardware I don't have access to and kernel features I am unfamiliar with. So this is ready for much wider testing. Changes since v5 (http://lkml.org/lkml/2010/2/17/271) o Fix a deadlock located by Thomas Gleixner that affects TREE_PREEMPT_RCU in some CPU-stall detection scenarios. o Add Dan Carpenter's cleanup to a mod_timer() in rcutorture. o Add a RCU_CPU_STALL_VERBOSE to enable dumping more information on tasks stalling the current RCU grace period. o Applied Acked-by lines that people have sent (thank you all!). Changes since v4 (http://lkml.org/lkml/2010/2/11/356) o Apply review comments from Peter Ziljstra. o Another documentation update. o Fixes that avoid overflowing signed integers. o Rebased Thomas Gleixner's raw-spinlock patch on this series. (Thomas's original at http://lkml.org/lkml/2010/2/17/182.) Changes since v3 (http://lkml.org/lkml/2010/1/14/505) o Fix a few more issues identified by the checking. o Add a documentation update. o Accelerate RCU grace periods when the current CPU is the last non-dyntick-idle CPU in the system, which is important for some multi-core battery-powered devices. Changes since v2 (http://lkml.org/lkml/2010/1/4/496): o Removed references to the check condition for the non-lockdep version of rcu_dereference_check(), thus preventing numerous build errors. o Create a CONFIG_PROVE_RCU (default disabled) so that developers who want to use lockdep only to debug locks aren't bothered by RCU-specific lockdep complaints that will no doubt persist for a little bit while some of the more obscure uses of RCU are reverse-engineered. o Fix a few more issues identified by the checking. o Add documentation in Documentation/RCU/lockdep.txt. Changes since v1 (http://lkml.org/lkml/2009/12/15/553): o Made SRCU have per-srcu_struct lockdep maps to prevent lockdep from conflating independent uses of SRCU, and updated the rcu_dereference() checking in rcutorture to match. o Fix a few issues identified by the checking. o Disable checking within RCU list macros, RCU radix trees, and IDR.