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* Merge branch 'core-rcu-for-linus' of ↵Linus Torvalds2013-07-02
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull RCU updates from Ingo Molnar: "The major changes: - Simplify RCU's grace-period and callback processing based on the new numbering for callbacks. - Removal of TINY_PREEMPT_RCU in favor of TREE_PREEMPT_RCU for single-CPU low-latency systems. - SRCU-related changes and fixes. - Miscellaneous fixes, including converting a few remaining printk() calls to pr_*(). - Documentation updates" * 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (32 commits) rcu: Shrink TINY_RCU by reworking CPU-stall ifdefs rcu: Shrink TINY_RCU by moving exit_rcu() rcu: Remove TINY_PREEMPT_RCU tracing documentation rcu: Consolidate rcutiny_plugin.h ifdefs rcu: Remove rcu_preempt_note_context_switch() rcu: Remove the CONFIG_TINY_RCU ifdefs in rcutiny.h rcu: Remove check_cpu_stall_preempt() rcu: Simplify RCU_TINY RCU callback invocation rcu: Remove rcu_preempt_process_callbacks() rcu: Remove rcu_preempt_remove_callbacks() rcu: Remove rcu_preempt_check_callbacks() rcu: Remove show_tiny_preempt_stats() rcu: Remove TINY_PREEMPT_RCU powerpc,kvm: fix imbalance srcu_read_[un]lock() rcu: Remove srcu_read_lock_raw() and srcu_read_unlock_raw(). rcu: Apply Dave Jones's NOCB Kconfig help feedback rcu: Merge adjacent identical ifdefs rcu: Drive quiescent-state-forcing delay from HZ rcu: Remove "Experimental" flags kthread: Add kworker kthreads to OS-jitter documentation ...
| * Merge branch 'rcu/next' of ↵Ingo Molnar2013-06-19
| |\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu into core/rcu Pull RCU changes from Paul E. McKenney: "The major changes for this series are: 1. Simplify RCU's grace-period and callback processing based on the new numbering for callbacks. These were posted to LKML at https://lkml.org/lkml/2013/5/20/330. 2. Documentation updates. These were posted to LKML at https://lkml.org/lkml/2013/5/20/348. 3. Miscellaneous fixes, including converting a few remaining printk() calls to pr_*(). These were posted to LKML at https://lkml.org/lkml/2013/5/20/324. 4. SRCU-related changes and fixes. These were posted to LKML at https://lkml.org/lkml/2013/5/20/425. 5. Removal of TINY_PREEMPT_RCU in favor of TREE_PREEMPT_RCU for single-CPU low-latency systems. These were posted to LKML at https://lkml.org/lkml/2013/5/20/427." Signed-off-by: Ingo Molnar <mingo@kernel.org>
| | *-----. Merge branches 'cbnum.2013.06.10a', 'doc.2013.06.10a', 'fixes.2013.06.10a', ↵Paul E. McKenney2013-06-10
| | |\ \ \ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 'srcu.2013.06.10a' and 'tiny.2013.06.10a' into HEAD cbnum.2013.06.10a: Apply simplifications stemming from the new callback numbering. doc.2013.06.10a: Documentation updates. fixes.2013.06.10a: Miscellaneous fixes. srcu.2013.06.10a: Updates to SRCU. tiny.2013.06.10a: Eliminate TINY_PREEMPT_RCU.
| | | | | | * rcu: Shrink TINY_RCU by reworking CPU-stall ifdefsPaul E. McKenney2013-06-10
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | TINY_RCU's reset_cpu_stall_ticks() and check_cpu_stalls() functions are defined unconditionally, and are empty functions if CONFIG_RCU_TRACE is disabled (which in turns disables detection of RCU CPU stalls). This commit saves a few lines of source code by defining these functions only if CONFIG_RCU_TRACE=y. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
| | | | | | * rcu: Shrink TINY_RCU by moving exit_rcu()Paul E. McKenney2013-06-10
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Now that TINY_PREEMPT_RCU is no more, exit_rcu() is always an empty function. But if TINY_RCU is going to have an empty function, it should be in include/linux/rcutiny.h, where it does not bloat the kernel. This commit therefore moves exit_rcu() out of kernel/rcupdate.c to kernel/rcutree_plugin.h, and places a static inline empty function in include/linux/rcutiny.h in order to shrink TINY_RCU a bit. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
| | | | | | * rcu: Remove TINY_PREEMPT_RCU tracing documentationPaul E. McKenney2013-06-10
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Because TINY_PREEMPT_RCU is no more, this commit removes its tracing formats from the documentation. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
| | | | | | * rcu: Consolidate rcutiny_plugin.h ifdefsPaul E. McKenney2013-06-10
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This commit rearranges code in order to allow ifdefs to be consolidated in kernel/rcutiny_plugin.h, simplifying the code. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
| | | | | | * rcu: Remove rcu_preempt_note_context_switch()Paul E. McKenney2013-06-10
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | With the removal of CONFIG_TINY_PREEMPT_RCU, rcu_preempt_note_context_switch() is now an empty function. This commit therefore eliminates it by inlining it. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
| | | | | | * rcu: Remove the CONFIG_TINY_RCU ifdefs in rcutiny.hPaul E. McKenney2013-06-10
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Now that CONFIG_TINY_PREEMPT_RCU is no more, this commit removes the CONFIG_TINY_RCU ifdefs from include/linux/rcutiny.h in favor of unconditionally compiling the CONFIG_TINY_RCU legs of those ifdefs. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> [ paulmck: Moved removal of #else to "Remove TINY_PREEMPT_RCU" as suggested by Josh Triplett. ] Reviewed-by: Josh Triplett <josh@joshtriplett.org>
| | | | | | * rcu: Remove check_cpu_stall_preempt()Paul E. McKenney2013-06-10
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | With the removal of CONFIG_TINY_PREEMPT_RCU, check_cpu_stall_preempt() is now an empty function. This commit therefore eliminates it by inlining it. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
| | | | | | * rcu: Simplify RCU_TINY RCU callback invocationPaul E. McKenney2013-06-10
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | TINY_PREEMPT_RCU could use a kthread to handle RCU callback invocation, which required an API to abstract kthread vs. softirq invocation. Now that TINY_PREEMPT_RCU is no longer with us, this commit retires this API in favor of direct use of the relevant softirq primitives. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
| | | | | | * rcu: Remove rcu_preempt_process_callbacks()Paul E. McKenney2013-06-10
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | With the removal of CONFIG_TINY_PREEMPT_RCU, rcu_preempt_process_callbacks() is now an empty function. This commit therefore eliminates it by inlining it. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
| | | | | | * rcu: Remove rcu_preempt_remove_callbacks()Paul E. McKenney2013-06-10
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | With the removal of CONFIG_TINY_PREEMPT_RCU, rcu_preempt_remove_callbacks() is now an empty function. This commit therefore eliminates it by inlining it. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
| | | | | | * rcu: Remove rcu_preempt_check_callbacks()Paul E. McKenney2013-06-10
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | With the removal of CONFIG_TINY_PREEMPT_RCU, rcu_preempt_check_callbacks() is now an empty function. This commit therefore eliminates it by inlining it. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
| | | | | | * rcu: Remove show_tiny_preempt_stats()Paul E. McKenney2013-06-10
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | With the removal of CONFIG_TINY_PREEMPT_RCU, show_tiny_preempt_stats() is now an empty function. This commit therefore eliminates it by inlining it. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
| | | | | | * rcu: Remove TINY_PREEMPT_RCUPaul E. McKenney2013-06-10
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | TINY_PREEMPT_RCU adds significant code and complexity, but does not offer commensurate benefits. People currently using TINY_PREEMPT_RCU can get much better memory footprint with TINY_RCU, or, if they really need preemptible RCU, they can use TREE_PREEMPT_RCU with a relatively minor degradation in memory footprint. Please note that this move has been widely publicized on LKML (https://lkml.org/lkml/2012/11/12/545) and on LWN (http://lwn.net/Articles/541037/). This commit therefore removes TINY_PREEMPT_RCU. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> [ paulmck: Updated to eliminate #else in rcutiny.h as suggested by Josh ] Reviewed-by: Josh Triplett <josh@joshtriplett.org>
| | | | | * | powerpc,kvm: fix imbalance srcu_read_[un]lock()Lai Jiangshan2013-06-10
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | At the point of up_out label in kvmppc_hv_setup_htab_rma(), srcu read lock is still held. We have to release it before return. Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com> Cc: Marcelo Tosatti <mtosatti@redhat.com> Cc: Gleb Natapov <gleb@redhat.com> Cc: Alexander Graf <agraf@suse.de> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: kvm@vger.kernel.org Cc: kvm-ppc@vger.kernel.org Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
| | | | | * | rcu: Remove srcu_read_lock_raw() and srcu_read_unlock_raw().Paul E. McKenney2013-06-10
| | | | | |/ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | These interfaces never did get used, so this commit removes them, their rcutorture tests, and documentation referencing them. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Lai Jiangshan <laijs@cn.fujitsu.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
| | | | * | rcu: Apply Dave Jones's NOCB Kconfig help feedbackPaul E. McKenney2013-06-10
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The Kconfig help text for the RCU_NOCB_CPU_NONE, RCU_NOCB_CPU_ZERO, and RCU_NOCB_CPU_ALL Kconfig options was unclear, so this commit adds a bit more detail. Reported-by: Dave Jones <davej@redhat.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
| | | | * | rcu: Merge adjacent identical ifdefsPaul E. McKenney2013-06-10
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Two ifdefs in kernel/rcupdate.c now have identical conditions with nothing between them, so the commit merges them into a single ifdef. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
| | | | * | rcu: Drive quiescent-state-forcing delay from HZPaul E. McKenney2013-06-10
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Systems with HZ=100 can have slow bootup times due to the default three-jiffy delays between quiescent-state forcing attempts. This commit therefore auto-tunes the RCU_JIFFIES_TILL_FORCE_QS value based on the value of HZ. However, this would break very large systems that require more time between quiescent-state forcing attempts. This commit therefore also ups the default delay by one jiffy for each 256 CPUs that might be on the system (based off of nr_cpu_ids at runtime, -not- NR_CPUS at build time). Updated to collapse #ifdefs for RCU_JIFFIES_TILL_FORCE_QS into a step-function definition as suggested by Josh Triplett. Reported-by: Paul Mackerras <paulus@au1.ibm.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
| | | | * | rcu: Remove "Experimental" flagsPaul E. McKenney2013-06-10
| | | | |/ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | After a release or two, features are no longer experimental. Therefore, this commit removes the "Experimental" tag from them. Reported-by: Paul Gortmaker <paul.gortmaker@windriver.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
| | | * | kthread: Add kworker kthreads to OS-jitter documentationPaul E. McKenney2013-06-10
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The kworker workqueue kthreads can also contribute to OS jitter. The amount of jitter depends on their use, so this commit adds documentation on avoiding OS jitter due to workqueue use. Reported-by: Jonathan Clairembault <jonathan.clairembault@novasparks.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
| | | * | nohz_full: Document additional restrictionsPaul E. McKenney2013-06-10
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This commit calls out the potential for slowing the tick even when there are multiple runnable processes per CPU, It also points out that current mainlined version keeps the tick going on at least one CPU even when all CPUs are otherwise idle. Finally, it notes the need for a 1-HZ tick in order to calculate CPU load, maintain sched average, compute CFS entity vruntime, compute avenrun, and carry out load balancing. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
| | | * | nohz_full: Update based on Sedat Dilek reviewPaul E. McKenney2013-06-10
| | | |/ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Make it more clear that there are three options, and give hints as to which of the three is most likely to be useful in different situations. Reported-by: Sedat Dilek <sedat.dilek@gmail.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
| | * | rcu: Move redundant call to note_gp_changes() into called functionPaul E. McKenney2013-06-10
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The __rcu_process_callbacks() invokes note_gp_changes() immediately before invoking rcu_check_quiescent_state(), which conditionally invokes that same function. This commit therefore eliminates the call to note_gp_changes() in __rcu_process_callbacks() in favor of making unconditional to call from rcu_check_quiescent_state() to note_gp_changes(). Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
| | * | rcu: Inline trivial wrapper function rcu_start_gp_per_cpu()Paul E. McKenney2013-06-10
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Given the changes that introduce note_gp_change(), rcu_start_gp_per_cpu() is now a trivial wrapper function with only one caller. This commit therefore inlines it into its sole call site. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
| | * | rcu: Eliminate check_for_new_grace_period() wrapper functionPaul E. McKenney2013-06-10
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | One of the calls to check_for_new_grace_period() is now redundant due to an immediately preceding call to note_gp_changes(). Eliminating this redundant call leaves a single caller, which is simpler if inlined. This commit therefore eliminates the redundant call and inlines the body of check_for_new_grace_period() into the single remaining call site. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
| | * | rcu: Merge __rcu_process_gp_end() into __note_gp_changes()Paul E. McKenney2013-06-10
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This commit eliminates some duplicated code by merging __rcu_process_gp_end() into __note_gp_changes(). Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
| | * | rcu: Switch callers from rcu_process_gp_end() to note_gp_changes()Paul E. McKenney2013-06-10
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Because note_gp_changes() now incorporates rcu_process_gp_end() function, this commit switches to the former and eliminates the latter. In addition, this commit changes external calls from __rcu_process_gp_end() to __note_gp_changes(). Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
| | * | rcu: Rename note_new_gpnum() to note_gp_changes()Paul E. McKenney2013-06-10
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Because note_new_gpnum() now also checks for the ends of old grace periods, this commit changes its name to note_gp_changes(). Later commits will merge rcu_process_gp_end() into note_gp_changes(). Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
| | * | rcu: Make __note_new_gpnum() check for ends of prior grace periodsPaul E. McKenney2013-06-10
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The current implementation can detect the beginning of a new grace period before noting the end of a previous grace period. Although the current implementation correctly handles this sort of nonsense, it would be good to reduce RCU's state space by making such nonsense unnecessary, which is now possible thanks to the fact that RCU's callback groups are now numbered. This commit therefore makes __note_new_gpnum() invoke __rcu_process_gp_end() in order to note the ends of prior grace periods before noting the beginnings of new grace periods. Of course, this now means that note_new_gpnum() notes both the beginnings and ends of grace periods, and could therefore be used in place of rcu_process_gp_end(). But that is a job for later commits. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
| | * | rcu: Move code to apply callback-numbering simplificationsPaul E. McKenney2013-06-10
| | |/ | | | | | | | | | | | | | | | | | | | | | | | | The addition of callback numbering allows combining the detection of the ends of old grace periods and the beginnings of new grace periods. This commit moves code to set the stage for this combining. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
| | * rcu: Convert rcutree_plugin.h printk callsPaul E. McKenney2013-06-10
| | | | | | | | | | | | | | | | | | | | | This commit converts printk() calls to the corresponding pr_*() calls. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
| | * rcu: Convert rcutree.c printk callsPaul E. McKenney2013-06-10
| | | | | | | | | | | | | | | | | | | | | This commit converts printk() calls to the corresponding pr_*() calls. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
* | | Merge branch 'core-mutexes-for-linus' of ↵Linus Torvalds2013-07-02
|\ \ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull WW mutex support from Ingo Molnar: "This tree adds support for wound/wait style locks, which the graphics guys would like to make use of in the TTM graphics subsystem. Wound/wait mutexes are used when other multiple lock acquisitions of a similar type can be done in an arbitrary order. The deadlock handling used here is called wait/wound in the RDBMS literature: The older tasks waits until it can acquire the contended lock. The younger tasks needs to back off and drop all the locks it is currently holding, ie the younger task is wounded. See this LWN.net description of W/W mutexes: https://lwn.net/Articles/548909/ The comments there outline specific usecases for this facility (which have already been implemented for the DRM tree). Also see Documentation/ww-mutex-design.txt for more details" * 'core-mutexes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: locking-selftests: Handle unexpected failures more strictly mutex: Add more w/w tests to test EDEADLK path handling mutex: Add more tests to lib/locking-selftest.c mutex: Add w/w tests to lib/locking-selftest.c mutex: Add w/w mutex slowpath debugging mutex: Add support for wound/wait style locks arch: Make __mutex_fastpath_lock_retval return whether fastpath succeeded or not
| * | | locking-selftests: Handle unexpected failures more strictlyMaarten Lankhorst2013-06-26
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | When CONFIG_PROVE_LOCKING is not enabled, more tests are expected to pass unexpectedly, but there no tests that should start to fail that pass with CONFIG_PROVE_LOCKING enabled. Signed-off-by: Maarten Lankhorst <maarten.lankhorst@canonical.com> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: dri-devel@lists.freedesktop.org Cc: linaro-mm-sig@lists.linaro.org Cc: rostedt@goodmis.org Cc: daniel@ffwll.ch Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/20130620113151.4001.77963.stgit@patser Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * | | mutex: Add more w/w tests to test EDEADLK path handlingMaarten Lankhorst2013-06-26
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Signed-off-by: Maarten Lankhorst <maarten.lankhorst@canonical.com> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: dri-devel@lists.freedesktop.org Cc: linaro-mm-sig@lists.linaro.org Cc: rostedt@goodmis.org Cc: daniel@ffwll.ch Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/20130620113141.4001.54331.stgit@patser Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * | | mutex: Add more tests to lib/locking-selftest.cMaarten Lankhorst2013-06-26
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | None of the ww_mutex codepaths should be taken in the 'normal' mutex calls. The easiest way to verify this is by using the normal mutex calls, and making sure o.ctx is unmodified. Signed-off-by: Maarten Lankhorst <maarten.lankhorst@canonical.com> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: dri-devel@lists.freedesktop.org Cc: linaro-mm-sig@lists.linaro.org Cc: robclark@gmail.com Cc: rostedt@goodmis.org Cc: daniel@ffwll.ch Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/20130620113130.4001.45423.stgit@patser Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * | | mutex: Add w/w tests to lib/locking-selftest.cMaarten Lankhorst2013-06-26
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This stresses the lockdep code in some ways specifically useful to ww_mutexes. It adds checks for most of the common locking errors. Signed-off-by: Maarten Lankhorst <maarten.lankhorst@canonical.com> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: dri-devel@lists.freedesktop.org Cc: linaro-mm-sig@lists.linaro.org Cc: robclark@gmail.com Cc: rostedt@goodmis.org Cc: daniel@ffwll.ch Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/20130620113124.4001.23186.stgit@patser Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * | | mutex: Add w/w mutex slowpath debuggingDaniel Vetter2013-06-26
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Injects EDEADLK conditions at pseudo-random interval, with exponential backoff up to UINT_MAX (to ensure that every lock operation still completes in a reasonable time). This way we can test the wound slowpath even for ww mutex users where contention is never expected, and the ww deadlock avoidance algorithm is only needed for correctness against malicious userspace. An example would be protecting kernel modesetting properties, which thanks to single-threaded X isn't really expected to contend, ever. I've looked into using the CONFIG_FAULT_INJECTION infrastructure, but decided against it for two reasons: - EDEADLK handling is mandatory for ww mutex users and should never affect the outcome of a syscall. This is in contrast to -ENOMEM injection. So fine configurability isn't required. - The fault injection framework only allows to set a simple probability for failure. Now the probability that a ww mutex acquire stage with N locks will never complete (due to too many injected EDEADLK backoffs) is zero. But the expected number of ww_mutex_lock operations for the completely uncontended case would be O(exp(N)). The per-acuiqire ctx exponential backoff solution choosen here only results in O(log N) overhead due to injection and so O(log N * N) lock operations. This way we can fail with high probability (and so have good test coverage even for fancy backoff and lock acquisition paths) without running into patalogical cases. Note that EDEADLK will only ever be injected when we managed to acquire the lock. This prevents any behaviour changes for users which rely on the EALREADY semantics. Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch> Signed-off-by: Maarten Lankhorst <maarten.lankhorst@canonical.com> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: dri-devel@lists.freedesktop.org Cc: linaro-mm-sig@lists.linaro.org Cc: rostedt@goodmis.org Cc: daniel@ffwll.ch Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/20130620113117.4001.21681.stgit@patser Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * | | mutex: Add support for wound/wait style locksMaarten Lankhorst2013-06-26
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Wound/wait mutexes are used when other multiple lock acquisitions of a similar type can be done in an arbitrary order. The deadlock handling used here is called wait/wound in the RDBMS literature: The older tasks waits until it can acquire the contended lock. The younger tasks needs to back off and drop all the locks it is currently holding, i.e. the younger task is wounded. For full documentation please read Documentation/ww-mutex-design.txt. References: https://lwn.net/Articles/548909/ Signed-off-by: Maarten Lankhorst <maarten.lankhorst@canonical.com> Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch> Acked-by: Rob Clark <robdclark@gmail.com> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: dri-devel@lists.freedesktop.org Cc: linaro-mm-sig@lists.linaro.org Cc: rostedt@goodmis.org Cc: daniel@ffwll.ch Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/51C8038C.9000106@canonical.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * | | arch: Make __mutex_fastpath_lock_retval return whether fastpath succeeded or notMaarten Lankhorst2013-06-26
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This will allow me to call functions that have multiple arguments if fastpath fails. This is required to support ticket mutexes, because they need to be able to pass an extra argument to the fail function. Originally I duplicated the functions, by adding __mutex_fastpath_lock_retval_arg. This ended up being just a duplication of the existing function, so a way to test if fastpath was called ended up being better. This also cleaned up the reservation mutex patch some by being able to call an atomic_set instead of atomic_xchg, and making it easier to detect if the wrong unlock function was previously used. Signed-off-by: Maarten Lankhorst <maarten.lankhorst@canonical.com> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: dri-devel@lists.freedesktop.org Cc: linaro-mm-sig@lists.linaro.org Cc: robclark@gmail.com Cc: rostedt@goodmis.org Cc: daniel@ffwll.ch Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/20130620113105.4001.83929.stgit@patser Signed-off-by: Ingo Molnar <mingo@kernel.org>
* | | | Merge branch 'core-locking-for-linus' of ↵Linus Torvalds2013-07-02
|\ \ \ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull locking changes from Ingo Molnar: "Four miscellanous standalone fixes for futexes, rtmutexes and Kconfig.locks." * 'core-locking-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: futex: Use freezable blocking call futex: Take hugepages into account when generating futex_key rtmutex: Document rt_mutex_adjust_prio_chain() locking: Fix copy/paste errors of "ARCH_INLINE_*_UNLOCK_BH"
| * | | | futex: Use freezable blocking callColin Cross2013-06-25
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Avoid waking up every thread sleeping in a futex_wait call during suspend and resume by calling a freezable blocking call. Previous patches modified the freezer to avoid sending wakeups to threads that are blocked in freezable blocking calls. This call was selected to be converted to a freezable call because it doesn't hold any locks or release any resources when interrupted that might be needed by another freezing task or a kernel driver during suspend, and is a common site where idle userspace tasks are blocked. Signed-off-by: Colin Cross <ccross@android.com> Cc: Rafael J. Wysocki <rjw@sisk.pl> Cc: arve@android.com Cc: Tejun Heo <tj@kernel.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Darren Hart <dvhart@linux.intel.com> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Al Viro <viro@zeniv.linux.org.uk> Link: http://lkml.kernel.org/r/1367458508-9133-8-git-send-email-ccross@android.com Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
| * | | | futex: Take hugepages into account when generating futex_keyZhang Yi2013-06-25
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The futex_keys of process shared futexes are generated from the page offset, the mapping host and the mapping index of the futex user space address. This should result in an unique identifier for each futex. Though this is not true when futexes are located in different subpages of an hugepage. The reason is, that the mapping index for all those futexes evaluates to the index of the base page of the hugetlbfs mapping. So a futex at offset 0 of the hugepage mapping and another one at offset PAGE_SIZE of the same hugepage mapping have identical futex_keys. This happens because the futex code blindly uses page->index. Steps to reproduce the bug: 1. Map a file from hugetlbfs. Initialize pthread_mutex1 at offset 0 and pthread_mutex2 at offset PAGE_SIZE of the hugetlbfs mapping. The mutexes must be initialized as PTHREAD_PROCESS_SHARED because PTHREAD_PROCESS_PRIVATE mutexes are not affected by this issue as their keys solely depend on the user space address. 2. Lock mutex1 and mutex2 3. Create thread1 and in the thread function lock mutex1, which results in thread1 blocking on the locked mutex1. 4. Create thread2 and in the thread function lock mutex2, which results in thread2 blocking on the locked mutex2. 5. Unlock mutex2. Despite the fact that mutex2 got unlocked, thread2 still blocks on mutex2 because the futex_key points to mutex1. To solve this issue we need to take the normal page index of the page which contains the futex into account, if the futex is in an hugetlbfs mapping. In other words, we calculate the normal page mapping index of the subpage in the hugetlbfs mapping. Mappings which are not based on hugetlbfs are not affected and still use page->index. Thanks to Mel Gorman who provided a patch for adding proper evaluation functions to the hugetlbfs code to avoid exposing hugetlbfs specific details to the futex code. [ tglx: Massaged changelog ] Signed-off-by: Zhang Yi <zhang.yi20@zte.com.cn> Reviewed-by: Jiang Biao <jiang.biao2@zte.com.cn> Tested-by: Ma Chenggong <ma.chenggong@zte.com.cn> Reviewed-by: 'Mel Gorman' <mgorman@suse.de> Acked-by: 'Darren Hart' <dvhart@linux.intel.com> Cc: 'Peter Zijlstra' <peterz@infradead.org> Cc: stable@vger.kernel.org Link: http://lkml.kernel.org/r/000101ce71a6%24a83c5880%24f8b50980%24@com Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
| * | | | rtmutex: Document rt_mutex_adjust_prio_chain()Juri Lelli2013-05-28
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Parameters and usage of rt_mutex_adjust_prio_chain() are already documented in Documentation/rt-mutex-design.txt. However, since this function is called from several paths with different semantics (related to the arguments), it is handy to have a quick reference directly in the code. Signed-off-by: Juri Lelli <juri.lelli@gmail.com> Cc: Clark Williams <williams@redhat.com> Cc: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/1368608650-7935-1-git-send-email-juri.lelli@gmail.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * | | | locking: Fix copy/paste errors of "ARCH_INLINE_*_UNLOCK_BH"Paul Bolle2013-05-28
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The Kconfig symbols ARCH_INLINE_READ_UNLOCK_IRQ, ARCH_INLINE_SPIN_UNLOCK_IRQ, and ARCH_INLINE_WRITE_UNLOCK_IRQ were added in v2.6.33, but have never actually been used. Ingo Molnar spotted that this is caused by three identical copy/paste erros. Eg, the Kconfig entry for INLINE_READ_UNLOCK_IRQ has an (optional) dependency on: ARCH_INLINE_READ_UNLOCK_BH were it apparently should depend on: ARCH_INLINE_READ_UNLOCK_IRQ instead. Likewise for the Kconfig entries for INLINE_SPIN_UNLOCK_IRQ and INLINE_WRITE_UNLOCK_IRQ. Fix these three errors. This never really caused any real problems as these symbols are set (or unset) in a group - but it's worth fixing it nevertheless. Reported-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Paul Bolle <pebolle@tiscali.nl> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/1368780693.1350.228.camel@x61.thuisdomein Signed-off-by: Ingo Molnar <mingo@kernel.org>
* | | | | Merge tag 'late-for-linus' of ↵Linus Torvalds2013-07-02
|\ \ \ \ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/arm/arm-soc Pull ARM SoC late changes from Arnd Bergmann: "These are changes that arrived a little late before the merge window or that have multiple dependencies on previous branches so they did not fit into one of the earlier ones. There are 10 branches merged here, a total of 39 non-merge commits. Contents are a mixed bag for the above reasons: * Two new SoC platforms: ST microelectronics stixxxx and the TI 'Nspire' graphing calculator. These should have been in the 'soc' branch but were a little late * Support for the Exynos 5420 variant in mach-exynos, which is based on the other exynos branches to avoid conflicts. * Various small changes for sh-mobile, ux500 and davinci * Common clk support for MSM" * tag 'late-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/arm/arm-soc: (39 commits) ARM: ux500: bail out on alien cpus ARM: davinci: da850: adopt to pinctrl-single change for configuring multiple pins serial: sh-sci: Initialise variables before access in sci_set_termios() ARM: stih41x: Add B2020 board support ARM: stih41x: Add B2000 board support ARM: sti: Add DEBUG_LL console support ARM: sti: Add STiH416 SOC support ARM: sti: Add STiH415 SOC support ARM: msm: Migrate to common clock framework ARM: msm: Make proc_comm clock control into a platform driver ARM: msm: Prepare clk_get() users in mach-msm for clock-pcom driver ARM: msm: Remove clock-7x30.h include file ARM: msm: Remove custom clk_set_{max,min}_rate() API ARM: msm: Remove custom clk_set_flags() API msm: iommu: Use clk_set_rate() instead of clk_set_min_rate() msm: iommu: Convert to clk_prepare/unprepare msm_sdcc: Convert to clk_prepare/unprepare usb: otg: msm: Convert to clk_prepare/unprepare msm_serial: Use devm_clk_get() and properly return errors msm_serial: Convert to clk_prepare/unprepare ...
| * \ \ \ \ Merge tag 'msm-clock-for-3.11b' of ↵Olof Johansson2013-06-27
| |\ \ \ \ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/davidb/linux-msm into next/late From David Brown: MSM clock updates for 3.11. Per Stephen Boyd's coverletter: Resending to collect higher level maintainer acks per Olof's request. The plan is to push this patchset through MSM to the arm-soc tree. This patchset moves the existing MSM clock code and affected drivers to the common clock framework. A prerequisite of moving to the common clock framework is to use clk_prepare() and clk_enable() so the first few patches migrate drivers to that call (clk_prepare() is a no-op on MSM right now). It also removes some custom clock APIs that MSM provides and finally moves the proc_comm clock code to the common struct clk. This patch series will be used as the foundation of the MSM 8660/8960 clock code that I plan to send out after this series. * tag 'msm-clock-for-3.11b' of git://git.kernel.org/pub/scm/linux/kernel/git/davidb/linux-msm: ARM: msm: Migrate to common clock framework ARM: msm: Make proc_comm clock control into a platform driver ARM: msm: Prepare clk_get() users in mach-msm for clock-pcom driver ARM: msm: Remove clock-7x30.h include file ARM: msm: Remove custom clk_set_{max,min}_rate() API ARM: msm: Remove custom clk_set_flags() API msm: iommu: Use clk_set_rate() instead of clk_set_min_rate() msm: iommu: Convert to clk_prepare/unprepare msm_sdcc: Convert to clk_prepare/unprepare usb: otg: msm: Convert to clk_prepare/unprepare msm_serial: Use devm_clk_get() and properly return errors msm_serial: Convert to clk_prepare/unprepare Acked-by: Chris Ball <cjb@laptop.org> # for msm_sdcc.c Signed-off-by: Olof Johansson <olof@lixom.net>