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2014-07-09Merge branches 'doc.2014.07.08a', 'fixes.2014.07.09a', ↵Paul E. McKenney
'maintainers.2014.07.08b', 'nocbs.2014.07.07a' and 'torture.2014.07.07a' into HEAD doc.2014.07.08a: Documentation updates. fixes.2014.07.09a: Miscellaneous fixes. maintainers.2014.07.08b: Maintainership updates. nocbs.2014.07.07a: Callback-offloading fixes. torture.2014.07.07a: Torture-test updates.
2014-07-09rcu: Fix a sparse warning in rcu_report_unblock_qs_rnp()Pranith Kumar
This commit annotates rcu_report_unblock_qs_rnp() in order to fix the following sparse warning: kernel/rcu/tree_plugin.h:990:13: warning: context imbalance in 'rcu_report_unblock_qs_rnp' - unexpected unlock Signed-off-by: Pranith Kumar <bobby.prani@gmail.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Lai Jiangshan <laijs@cn.fujitsu.com>
2014-07-09rcu: Fix a sparse warning in rcu_initiate_boost()Pranith Kumar
This commit annotates rcu_initiate_boost() fixes the following sparse warning: kernel/rcu/tree_plugin.h:1494:13: warning: context imbalance in 'rcu_initiate_boost' - unexpected unlock Signed-off-by: Pranith Kumar <bobby.prani@gmail.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Lai Jiangshan <laijs@cn.fujitsu.com>
2014-07-09rcu: Fix __rcu_reclaim() to use true/false for boolPaul E. McKenney
The __rcu_reclaim() function returned 0/1, which is not proper for a function of type bool. This commit therefore converts to false/true. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Lai Jiangshan <laijs@cn.fujitsu.com>
2014-07-09rcu: Remove CONFIG_PROVE_RCU_DELAYPaul E. McKenney
The CONFIG_PROVE_RCU_DELAY Kconfig parameter doesn't appear to be very effective at finding race conditions, so this commit removes it. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Andi Kleen <ak@linux.intel.com> [ paulmck: Remove definition and uses as noted by Paul Bolle. ]
2014-07-09rcu: Use __this_cpu_read() instead of per_cpu_ptr()Shan Wei
The __this_cpu_read() function produces better code than does per_cpu_ptr() on both ARM and x86. For example, gcc (Ubuntu/Linaro 4.7.3-12ubuntu1) 4.7.3 produces the following: ARMv7 per_cpu_ptr(): force_quiescent_state: mov r3, sp @, bic r1, r3, #8128 @ tmp171,, ldr r2, .L98 @ tmp169, bic r1, r1, #63 @ tmp170, tmp171, ldr r3, [r0, #220] @ __ptr, rsp_6(D)->rda ldr r1, [r1, #20] @ D.35903_68->cpu, D.35903_68->cpu mov r6, r0 @ rsp, rsp ldr r2, [r2, r1, asl #2] @ tmp173, __per_cpu_offset add r3, r3, r2 @ tmp175, __ptr, tmp173 ldr r5, [r3, #12] @ rnp_old, D.29162_13->mynode ARMv7 __this_cpu_read(): force_quiescent_state: ldr r3, [r0, #220] @ rsp_7(D)->rda, rsp_7(D)->rda mov r6, r0 @ rsp, rsp add r3, r3, #12 @ __ptr, rsp_7(D)->rda, ldr r5, [r2, r3] @ rnp_old, *D.29176_13 Using gcc 4.8.2: x86_64 per_cpu_ptr(): movl %gs:cpu_number,%edx # cpu_number, pscr_ret__ movslq %edx, %rdx # pscr_ret__, pscr_ret__ movq __per_cpu_offset(,%rdx,8), %rdx # __per_cpu_offset, tmp93 movq %rdi, %r13 # rsp, rsp movq 1000(%rdi), %rax # rsp_9(D)->rda, __ptr movq 24(%rdx,%rax), %r12 # _15->mynode, rnp_old x86_64 __this_cpu_read(): movq %rdi, %r13 # rsp, rsp movq 1000(%rdi), %rax # rsp_9(D)->rda, rsp_9(D)->rda movq %gs:24(%rax),%r12 # _10->mynode, rnp_old Because this change produces significant benefits for these two very diverse architectures, this commit makes this change. Signed-off-by: Shan Wei <davidshan@tencent.com> Acked-by: Christoph Lameter <cl@linux.com> Signed-off-by: Pranith Kumar <bobby.prani@gmail.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org> Reviewed-by: Lai Jiangshan <laijs@cn.fujitsu.com>
2014-07-09rcu: Don't use NMIs to dump other CPUs' stacksPaul E. McKenney
Although NMI-based stack dumps are in principle more accurate, they are also more likely to trigger deadlocks. This commit therefore replaces all uses of trigger_all_cpu_backtrace() with rcu_dump_cpu_stacks(), so that the CPU detecting an RCU CPU stall does the stack dumping. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Lai Jiangshan <laijs@cn.fujitsu.com>
2014-07-09rcu: Bind grace-period kthreads to non-NO_HZ_FULL CPUsPaul E. McKenney
Binding the grace-period kthreads to the timekeeping CPU resulted in significant performance decreases for some workloads. For more detail, see: https://lkml.org/lkml/2014/6/3/395 for benchmark numbers https://lkml.org/lkml/2014/6/4/218 for CPU statistics It turns out that it is necessary to bind the grace-period kthreads to the timekeeping CPU only when all but CPU 0 is a nohz_full CPU on the one hand or if CONFIG_NO_HZ_FULL_SYSIDLE=y on the other. In other cases, it suffices to bind the grace-period kthreads to the set of non-nohz_full CPUs. This commit therefore creates a tick_nohz_not_full_mask that is the complement of tick_nohz_full_mask, and then binds the grace-period kthread to the set of CPUs indicated by this new mask, which covers the CONFIG_NO_HZ_FULL_SYSIDLE=n case. The CONFIG_NO_HZ_FULL_SYSIDLE=y case still binds the grace-period kthreads to the timekeeping CPU. This commit also includes the tick_nohz_full_enabled() check suggested by Frederic Weisbecker. Reported-by: Jet Chen <jet.chen@intel.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> [ paulmck: Created housekeeping_affine() and housekeeping_mask per fweisbec feedback. ]
2014-07-09rcu: Simplify priority boosting by putting rt_mutex in rcu_nodePaul E. McKenney
RCU priority boosting currently checks for boosting via a pointer in task_struct. However, this is not needed: As Oleg noted, if the rt_mutex is placed in the rcu_node instead of on the booster's stack, the boostee can simply check it see if it owns the lock. This commit makes this change, shrinking task_struct by one pointer and the kernel by thirteen lines. Suggested-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2014-07-09rcu: Check both root and current rcu_node when setting up future grace periodPranith Kumar
The rcu_start_future_gp() function checks the current rcu_node's ->gpnum and ->completed twice, once without ACCESS_ONCE() and once with it. Which is pointless because we hold that rcu_node's ->lock at that point. The intent was to check the current rcu_node structure and the root rcu_node structure, the latter locklessly with ACCESS_ONCE(). This commit therefore makes that change. The reason that it is safe to locklessly check the root rcu_nodes's ->gpnum and ->completed fields is that we hold the current rcu_node's ->lock, which constrains the root rcu_node's ability to change its ->gpnum and ->completed fields. Of course, if there is a single rcu_node structure, then rnp_root==rnp, and holding the lock prevents all changes. If there is more than one rcu_node structure, then the code updates the fields in the following order: 1. Increment rnp_root->gpnum to start new grace period. 2. Increment rnp->gpnum to initialize the current rcu_node, continuing initialization for the new grace period. 3. Increment rnp_root->completed to end the current grace period. 4. Increment rnp->completed to continue cleaning up after the old grace period. So there are four possible combinations of relative values of these four fields: N N N N: RCU idle, new grace period must be initiated. Although rnp_root->gpnum might be incremented immediately after we check, that will just result in unnecessary work. The grace period already started, and we try to start it. N+1 N N N: RCU grace period just started. No further change is possible because we hold rnp->lock, so the checks of rnp_root->gpnum and rnp_root->completed are stable. We know that our request for a future grace period will be seen during grace-period cleanup. N+1 N N+1 N: RCU grace period is ongoing. Because rnp->gpnum is different than rnp->completed, we won't even look at rnp_root->gpnum and rnp_root->completed, so the possible concurrent change to rnp_root->completed does not matter. We know that our request for a future grace period will be seen during grace-period cleanup, which cannot pass this rcu_node because we hold its ->lock. N+1 N+1 N+1 N: RCU grace period has ended, but not yet been cleaned up. Because rnp->gpnum is different than rnp->completed, we won't look at rnp_root->gpnum and rnp_root->completed, so the possible concurrent change to rnp_root->completed does not matter. We know that our request for a future grace period will be seen during grace-period cleanup, which cannot pass this rcu_node because we hold its ->lock. Therefore, despite initial appearances, the lockless check is safe. Signed-off-by: Pranith Kumar <bobby.prani@gmail.com> [ paulmck: Update comment to say why the lockless check is safe. ] Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2014-07-09rcu: Allow post-unlock reference for rt_mutexPaul E. McKenney
The current approach to RCU priority boosting uses an rt_mutex strictly for its priority-boosting side effects. The rt_mutex_init_proxy_locked() function is used by the booster to initialize the lock as held by the boostee. The booster then uses rt_mutex_lock() to acquire this rt_mutex, which priority-boosts the boostee. When the boostee reaches the end of its outermost RCU read-side critical section, it checks a field in its task structure to see whether it has been boosted, and, if so, uses rt_mutex_unlock() to release the rt_mutex. The booster can then go on to boost the next task that is blocking the current RCU grace period. But reasonable implementations of rt_mutex_unlock() might result in the boostee referencing the rt_mutex's data after releasing it. But the booster might have re-initialized the rt_mutex between the time that the boostee released it and the time that it later referenced it. This is clearly asking for trouble, so this commit introduces a completion that forces the booster to wait until the boostee has completely finished with the rt_mutex, thus avoiding the case where the booster is re-initializing the rt_mutex before the last boostee's last reference to that rt_mutex. This of course does introduce some overhead, but the priority-boosting code paths are miles from any possible fastpath, and the overhead of executing the completion will normally be quite small compared to the overhead of priority boosting and deboosting, so this should be OK. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2014-07-09rcu: Loosen __call_rcu()'s rcu_head alignment constraintPaul E. McKenney
The m68k architecture aligns only to 16-bit boundaries, which can cause the align-to-32-bits check in __call_rcu() to trigger. Because there is currently no known potential need for more than one low-order bit, this commit loosens the check to 16-bit boundaries. Reported-by: Greg Ungerer <gerg@uclinux.org> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Lai Jiangshan <laijs@cn.fujitsu.com>
2014-07-09rcu: Eliminate read-modify-write ACCESS_ONCE() callsPaul E. McKenney
RCU contains code of the following forms: ACCESS_ONCE(x)++; ACCESS_ONCE(x) += y; ACCESS_ONCE(x) -= y; Now these constructs do operate correctly, but they really result in a pair of volatile accesses, one to do the load and another to do the store. This can be confusing, as the casual reader might well assume that (for example) gcc might generate a memory-to-memory add instruction for each of these three cases. In fact, gcc will do no such thing. Also, there is a good chance that the kernel will move to separate load and store variants of ACCESS_ONCE(), and constructs like the above could easily confuse both people and scripts attempting to make that sort of change. Finally, most of RCU's read-modify-write uses of ACCESS_ONCE() really only need the store to be volatile, so that the read-modify-write form might be misleading. This commit therefore changes the above forms in RCU so that each instance of ACCESS_ONCE() either does a load or a store, but not both. In a few cases, ACCESS_ONCE() was not critical, for example, for maintaining statisitics. In these cases, ACCESS_ONCE() has been dispensed with entirely. Suggested-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2014-07-09rcu: Remove redundant ACCESS_ONCE() from tick_do_timer_cpuPaul E. McKenney
In kernels built with CONFIG_NO_HZ_FULL, tick_do_timer_cpu is constant once boot completes. Thus, there is no need to wrap it in ACCESS_ONCE() in code that is built only when CONFIG_NO_HZ_FULL. This commit therefore removes the redundant ACCESS_ONCE(). Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Acked-by: Frederic Weisbecker <fweisbec@gmail.com> Reviewed-by: Lai Jiangshan <laijs@cn.fujitsu.com>
2014-07-09rcu: Make rcu node arrays static const char * constFabian Frederick
Those two arrays are being passed to lockdep_init_map(), which expects const char *, and are stored in lockdep_map the same way. Cc: Dipankar Sarma <dipankar@in.ibm.com> Cc: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Fabian Frederick <fabf@skynet.be> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2014-07-09signal: Explain local_irq_save() callPaul E. McKenney
The explicit local_irq_save() in __lock_task_sighand() is needed to avoid a potential deadlock condition, as noted in a841796f11c90d53 (signal: align __lock_task_sighand() irq disabling and RCU). However, someone reading the code might be forgiven for concluding that this separate local_irq_save() was completely unnecessary. This commit therefore adds a comment referencing the shiny new block comment on rcu_read_unlock(). Reported-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Acked-by: Oleg Nesterov <oleg@redhat.com> Reviewed-by: Lai Jiangshan <laijs@cn.fujitsu.com>
2014-07-09rcu: Handle obsolete references to TINY_PREEMPT_RCUPaul E. McKenney
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Lai Jiangshan <laijs@cn.fujitsu.com>
2014-07-09rcu: Document deadlock-avoidance information for rcu_read_unlock()Paul E. McKenney
Reported-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Lai Jiangshan <laijs@cn.fujitsu.com>
2014-07-08scripts: Teach get_maintainer.pl about the new "R:" tagJoe Perches
We can now designate reviewers in the MAINTAINERS file with the new "R:" tag, so this commit teaches get_maintainers.pl to add their email addresses. Signed-off-by: Joe Perches <joe@perches.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2014-07-08rcu: Update rcu torture maintainership filename patternsJoe Perches
Commit 51b1130eb582 ("rcutorture: Abstract rcu_torture_random()") moved the file, so this commit updates the patterns. Signed-off-by: Joe Perches <joe@perches.com> cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2014-07-08rcu: Update RCU maintainershipPaul E. McKenney
Drop Dipankar Sarma at his request (https://lkml.org/lkml/2014/6/2/628), add Josh Triplett based on long-term review, contributions, and agreement to take on this role (https://lkml.org/lkml/2014/6/2/554). Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2014-07-08documentation: Add pointer to percpu-ref for RCU and refcountPaul E. McKenney
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org> Reviewed-by: Lai Jiangshan <laijs@cn.fujitsu.com>
2014-07-08documentation: Add acquire/release barriers to pairing rulesPaul E. McKenney
It is possible to pair acquire and release barriers with other barriers, so this commit adds them to the list in the SMP barrier pairing section. Reported-by: Lai Jiangshan <laijs@cn.fujitsu.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Tejun Heo <tj@kernel.org> Reviewed-by: Josh Triplett <josh@joshtriplett.org> [ paulmck: Updated pairing discussion as suggested by Peter Zijlstra. ]
2014-07-08documentation: Update reference, kerneltrap.org no longer worksPranith Kumar
The kerneltrap.org site no longer works, so this commit updates it to a working reference, namely gmane. Signed-off-by: Pranith Kumar <bobby.prani@gmail.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2014-07-08documentation: Clarify wake-up/memory-barrier relationshipPaul E. McKenney
This commit adds an example demonstrating that if a wake_up() doesn't actually wake something up, no memory ordering is provided. Reported-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org> Reviewed-by: Lai Jiangshan <laijs@cn.fujitsu.com> Acked-by: Peter Zijlstra <peterz@infradead.org>
2014-07-07rcu: Don't offload callbacks unless specifically requestedPaul E. McKenney
Enabling NO_HZ_FULL currently has the side effect of enabling callback offloading on all CPUs. This results in lots of additional rcuo kthreads, and can also increase context switching and wakeups, even in cases where callback offloading is neither needed nor particularly desirable. This commit therefore enables callback offloading on a given CPU only if specifically requested at build time or boot time, or if that CPU has been specifically designated (again, either at build time or boot time) as a nohz_full CPU. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2014-07-07rcu: Parallelize and economize NOCB kthread wakeupsPaul E. McKenney
An 80-CPU system with a context-switch-heavy workload can require so many NOCB kthread wakeups that the RCU grace-period kthreads spend several tens of percent of a CPU just awakening things. This clearly will not scale well: If you add enough CPUs, the RCU grace-period kthreads would get behind, increasing grace-period latency. To avoid this problem, this commit divides the NOCB kthreads into leaders and followers, where the grace-period kthreads awaken the leaders each of whom in turn awakens its followers. By default, the number of groups of kthreads is the square root of the number of CPUs, but this default may be overridden using the rcutree.rcu_nocb_leader_stride boot parameter. This reduces the number of wakeups done per grace period by the RCU grace-period kthread by the square root of the number of CPUs, but of course by shifting those wakeups to the leaders. In addition, because the leaders do grace periods on behalf of their respective followers, the number of wakeups of the followers decreases by up to a factor of two. Instead of being awakened once when new callbacks arrive and again at the end of the grace period, the followers are awakened only at the end of the grace period. For a numerical example, in a 4096-CPU system, the grace-period kthread would awaken 64 leaders, each of which would awaken its 63 followers at the end of the grace period. This compares favorably with the 79 wakeups for the grace-period kthread on an 80-CPU system. Reported-by: Rik van Riel <riel@redhat.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2014-07-07torture: Avoid format string leak to thead nameKees Cook
Since the torture-test thread creation interface does not include format string arguments, this commit makes sure the name can never be accidentally processed as a format string. Signed-off-by: Kees Cook <keescook@chromium.org> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2014-07-07rcu: Add designated reviewers for RCUPaul E. McKenney
Adding Steven Rostedt, Mathieu Desnoyers, and Lai Jiangshan as designated RCU reviewers based on recent emails: o https://lkml.org/lkml/2014/6/2/578 (Steven) o https://lkml.org/lkml/2014/6/2/621 (Mathieu) o https://lkml.org/lkml/2014/6/3/897 (Lai) Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2014-07-07MAINTAINERS: Add "R:" designated-reviewers tagPaul E. McKenney
A ksummit-discuss email thread looked at the difficulty recruiting and retaining reviewers. Paul Walmsley also noted the need for patch submitters to know who the key reviewers are and suggested adding an "R:" tag to the MAINTAINERS file to record this information on a per-subsystem basis. This commit does just that, and a subsequent commit tags the designated reviewer for the RCU-related subsystems. http://lists.linuxfoundation.org/pipermail/ksummit-discuss/2014-May/000830.html Suggested-by: Paul Walmsley <paul@pwsan.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org> Acked-by: Steven Rostedt <rostedt@goodmis.org>
2014-06-26torture: Clean up diagnostics from --buildonly runsPaul E. McKenney
Currently the post-processing complains about the lack of rcutorture output when --buildonly is set and also emits misleading messages about kernels being started and finishing. This commit suppresses these complaints and messages. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2014-06-26torture: Enable versions without CFcommon to function correctlyPaul E. McKenney
The CFcommon file must now be present, which makes using the current scripts against old kernel versions cumbersome. This commit therefore makes the CFcommon file be optional, so that old kernel versions can be used with current torture scripts. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2014-06-23rcu: Reduce overhead of cond_resched() checks for RCUPaul E. McKenney
Commit ac1bea85781e (Make cond_resched() report RCU quiescent states) fixed a problem where a CPU looping in the kernel with but one runnable task would give RCU CPU stall warnings, even if the in-kernel loop contained cond_resched() calls. Unfortunately, in so doing, it introduced performance regressions in Anton Blanchard's will-it-scale "open1" test. The problem appears to be not so much the increased cond_resched() path length as an increase in the rate at which grace periods complete, which increased per-update grace-period overhead. This commit takes a different approach to fixing this bug, mainly by moving the RCU-visible quiescent state from cond_resched() to rcu_note_context_switch(), and by further reducing the check to a simple non-zero test of a single per-CPU variable. However, this approach requires that the force-quiescent-state processing send resched IPIs to the offending CPUs. These will be sent only once the grace period has reached an age specified by the boot/sysfs parameter rcutree.jiffies_till_sched_qs, or once the grace period reaches an age halfway to the point at which RCU CPU stall warnings will be emitted, whichever comes first. Reported-by: Dave Hansen <dave.hansen@intel.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Andi Kleen <ak@linux.intel.com> Cc: Christoph Lameter <cl@gentwo.org> Cc: Mike Galbraith <umgwanakikbuti@gmail.com> Cc: Eric Dumazet <eric.dumazet@gmail.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org> [ paulmck: Made rcu_momentary_dyntick_idle() as suggested by the ktest build robot. Also fixed smp_mb() comment as noted by Oleg Nesterov. ] Merge with e552592e (Reduce overhead of cond_resched() checks for RCU) Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2014-06-23rcu: Export debug_init_rcu_head() and and debug_init_rcu_head()Paul E. McKenney
Currently, call_rcu() relies on implicit allocation and initialization for the debug-objects handling of RCU callbacks. If you hammer the kernel hard enough with Sasha's modified version of trinity, you can end up with the sl*b allocators recursing into themselves via this implicit call_rcu() allocation. This commit therefore exports the debug_init_rcu_head() and debug_rcu_head_free() functions, which permits the allocators to allocated and pre-initialize the debug-objects information, so that there no longer any need for call_rcu() to do that initialization, which in turn prevents the recursion into the memory allocators. Reported-by: Sasha Levin <sasha.levin@oracle.com> Suggested-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Acked-by: Thomas Gleixner <tglx@linutronix.de> Looks-good-to: Christoph Lameter <cl@linux.com>
2014-06-15Linux 3.16-rc1Linus Torvalds
2014-06-15Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/netLinus Torvalds
Pull networking fixes from David Miller: 1) Fix checksumming regressions, from Tom Herbert. 2) Undo unintentional permissions changes for SCTP rto_alpha and rto_beta sysfs knobs, from Denial Borkmann. 3) VXLAN, like other IP tunnels, should advertize it's encapsulation size using dev->needed_headroom instead of dev->hard_header_len. From Cong Wang. * git://git.kernel.org/pub/scm/linux/kernel/git/davem/net: net: sctp: fix permissions for rto_alpha and rto_beta knobs vxlan: Checksum fixes net: add skb_pop_rcv_encapsulation udp: call __skb_checksum_complete when doing full checksum net: Fix save software checksum complete net: Fix GSO constants to match NETIF flags udp: ipv4: do not waste time in __udp4_lib_mcast_demux_lookup vxlan: use dev->needed_headroom instead of dev->hard_header_len MAINTAINERS: update cxgb4 maintainer
2014-06-15Merge tag 'clk-for-linus-3.16-part2' of ↵Linus Torvalds
git://git.linaro.org/people/mike.turquette/linux Pull more clock framework updates from Mike Turquette: "This contains the second half the of the clk changes for 3.16. They are simply fixes and code refactoring for the OMAP clock drivers. The sunxi clock driver changes include splitting out the one mega-driver into several smaller pieces and adding support for the A31 SoC clocks" * tag 'clk-for-linus-3.16-part2' of git://git.linaro.org/people/mike.turquette/linux: (25 commits) clk: sunxi: document PRCM clock compatible strings clk: sunxi: add PRCM (Power/Reset/Clock Management) clks support clk: sun6i: Protect SDRAM gating bit clk: sun6i: Protect CPU clock clk: sunxi: Rework clock protection code clk: sunxi: Move the GMAC clock to a file of its own clk: sunxi: Move the 24M oscillator to a file of its own clk: sunxi: Remove calls to clk_put clk: sunxi: document new A31 USB clock compatible clk: sunxi: Implement A31 USB clock ARM: dts: OMAP5/DRA7: use omap5-mpu-dpll-clock capable of dealing with higher frequencies CLK: TI: dpll: support OMAP5 MPU DPLL that need special handling for higher frequencies ARM: OMAP5+: dpll: support Duty Cycle Correction(DCC) CLK: TI: clk-54xx: Set the rate for dpll_abe_m2x2_ck CLK: TI: Driver for DRA7 ATL (Audio Tracking Logic) dt:/bindings: DRA7 ATL (Audio Tracking Logic) clock bindings ARM: dts: dra7xx-clocks: Correct name for atl clkin3 clock CLK: TI: gate: add composite interface clock to OMAP2 only build ARM: OMAP2: clock: add DT boot support for cpufreq_ck CLK: TI: OMAP2: add clock init support ...
2014-06-15Merge git://git.infradead.org/users/willy/linux-nvmeLinus Torvalds
Pull NVMe update from Matthew Wilcox: "Mostly bugfixes again for the NVMe driver. I'd like to call out the exported tracepoint in the block layer; I believe Keith has cleared this with Jens. We've had a few reports from people who're really pounding on NVMe devices at scale, hence the timeout changes (and new module parameters), hotplug cpu deadlock, tracepoints, and minor performance tweaks" [ Jens hadn't seen that tracepoint thing, but is ok with it - it will end up going away when mq conversion happens ] * git://git.infradead.org/users/willy/linux-nvme: (22 commits) NVMe: Fix START_STOP_UNIT Scsi->NVMe translation. NVMe: Use Log Page constants in SCSI emulation NVMe: Define Log Page constants NVMe: Fix hot cpu notification dead lock NVMe: Rename io_timeout to nvme_io_timeout NVMe: Use last bytes of f/w rev SCSI Inquiry NVMe: Adhere to request queue block accounting enable/disable NVMe: Fix nvme get/put queue semantics NVMe: Delete NVME_GET_FEAT_TEMP_THRESH NVMe: Make admin timeout a module parameter NVMe: Make iod bio timeout a parameter NVMe: Prevent possible NULL pointer dereference NVMe: Fix the buffer size passed in GetLogPage(CDW10.NUMD) NVMe: Update data structures for NVMe 1.2 NVMe: Enable BUILD_BUG_ON checks NVMe: Update namespace and controller identify structures to the 1.1a spec NVMe: Flush with data support NVMe: Configure support for block flush NVMe: Add tracepoints NVMe: Protect against badly formatted CQEs ...
2014-06-15net: sctp: fix permissions for rto_alpha and rto_beta knobsDaniel Borkmann
Commit 3fd091e73b81 ("[SCTP]: Remove multiple levels of msecs to jiffies conversions.") has silently changed permissions for rto_alpha and rto_beta knobs from 0644 to 0444. The purpose of this was to discourage users from tweaking rto_alpha and rto_beta knobs in production environments since they are key to correctly compute rtt/srtt. RFC4960 under section 6.3.1. RTO Calculation says regarding rto_alpha and rto_beta under rule C3 and C4: [...] C3) When a new RTT measurement R' is made, set RTTVAR <- (1 - RTO.Beta) * RTTVAR + RTO.Beta * |SRTT - R'| and SRTT <- (1 - RTO.Alpha) * SRTT + RTO.Alpha * R' Note: The value of SRTT used in the update to RTTVAR is its value before updating SRTT itself using the second assignment. After the computation, update RTO <- SRTT + 4 * RTTVAR. C4) When data is in flight and when allowed by rule C5 below, a new RTT measurement MUST be made each round trip. Furthermore, new RTT measurements SHOULD be made no more than once per round trip for a given destination transport address. There are two reasons for this recommendation: First, it appears that measuring more frequently often does not in practice yield any significant benefit [ALLMAN99]; second, if measurements are made more often, then the values of RTO.Alpha and RTO.Beta in rule C3 above should be adjusted so that SRTT and RTTVAR still adjust to changes at roughly the same rate (in terms of how many round trips it takes them to reflect new values) as they would if making only one measurement per round-trip and using RTO.Alpha and RTO.Beta as given in rule C3. However, the exact nature of these adjustments remains a research issue. [...] While it is discouraged to adjust rto_alpha and rto_beta and not further specified how to adjust them, the RFC also doesn't explicitly forbid it, but rather gives a RECOMMENDED default value (rto_alpha=3, rto_beta=2). We have a couple of users relying on the old permissions before they got changed. That said, if someone really has the urge to adjust them, we could allow it with a warning in the log. Fixes: 3fd091e73b81 ("[SCTP]: Remove multiple levels of msecs to jiffies conversions.") Signed-off-by: Daniel Borkmann <dborkman@redhat.com> Cc: Vlad Yasevich <vyasevich@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2014-06-15Merge branch 'csum_fixes'David S. Miller
Tom Herbert says: ==================== Fixes related to some recent checksum modifications. - Fix GSO constants to match NETIF flags - Fix logic in saving checksum complete in __skb_checksum_complete - Call __skb_checksum_complete from UDP if we are checksumming over whole packet in order to save checksum. - Fixes to VXLAN to work correctly with checksum complete ==================== Signed-off-by: David S. Miller <davem@davemloft.net>
2014-06-15vxlan: Checksum fixesTom Herbert
Call skb_pop_rcv_encapsulation and postpull_rcsum for the Ethernet header to work properly with checksum complete. Signed-off-by: Tom Herbert <therbert@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2014-06-15net: add skb_pop_rcv_encapsulationTom Herbert
This function is used by UDP encapsulation protocols in RX when crossing encapsulation boundary. If ip_summed is set to CHECKSUM_UNNECESSARY and encapsulation is not set, change to CHECKSUM_NONE since the checksum has not been validated within the encapsulation. Clears csum_valid by the same rationale. Signed-off-by: Tom Herbert <therbert@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2014-06-15udp: call __skb_checksum_complete when doing full checksumTom Herbert
In __udp_lib_checksum_complete check if checksum is being done over all the data (len is equal to skb->len) and if it is call __skb_checksum_complete instead of __skb_checksum_complete_head. This allows checksum to be saved in checksum complete. Signed-off-by: Tom Herbert <therbert@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2014-06-15net: Fix save software checksum completeTom Herbert
Geert reported issues regarding checksum complete and UDP. The logic introduced in commit 7e3cead5172927732f51fde ("net: Save software checksum complete") is not correct. This patch: 1) Restores code in __skb_checksum_complete_header except for setting CHECKSUM_UNNECESSARY. This function may be calculating checksum on something less than skb->len. 2) Adds saving checksum to __skb_checksum_complete. The full packet checksum 0..skb->len is calculated without adding in pseudo header. This value is saved in skb->csum and then the pseudo header is added to that to derive the checksum for validation. 3) In both __skb_checksum_complete_header and __skb_checksum_complete, set skb->csum_valid to whether checksum of zero was computed. This allows skb_csum_unnecessary to return true without changing to CHECKSUM_UNNECESSARY which was done previously. 4) Copy new csum related bits in __copy_skb_header. Reported-by: Geert Uytterhoeven <geert@linux-m68k.org> Signed-off-by: Tom Herbert <therbert@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2014-06-15net: Fix GSO constants to match NETIF flagsTom Herbert
Joseph Gasparakis reported that VXLAN GSO offload stopped working with i40e device after recent UDP changes. The problem is that the SKB_GSO_* bits are out of sync with the corresponding NETIF flags. This patch fixes that. Also, we add BUILD_BUG_ONs in net_gso_ok for several GSO constants that were missing to avoid the problem in the future. Reported-by: Joseph Gasparakis <joseph.gasparakis@intel.com> Signed-off-by: Tom Herbert <therbert@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2014-06-14Merge tag 'scsi-for-linus' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi Pull more SCSI updates from James Bottomley: "This is just a couple of drivers (hpsa and lpfc) that got left out for further testing in linux-next. We also have one fix to a prior submission (qla2xxx sparse)" * tag 'scsi-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi: (36 commits) qla2xxx: fix sparse warnings introduced by previous target mode t10-dif patch lpfc: Update lpfc version to driver version 10.2.8001.0 lpfc: Fix ExpressLane priority setup lpfc: mark old devices as obsolete lpfc: Fix for initializing RRQ bitmap lpfc: Fix for cleaning up stale ring flag and sp_queue_event entries lpfc: Update lpfc version to driver version 10.2.8000.0 lpfc: Update Copyright on changed files from 8.3.45 patches lpfc: Update Copyright on changed files lpfc: Fixed locking for scsi task management commands lpfc: Convert runtime references to old xlane cfg param to fof cfg param lpfc: Fix FW dump using sysfs lpfc: Fix SLI4 s abort loop to process all FCP rings and under ring_lock lpfc: Fixed kernel panic in lpfc_abort_handler lpfc: Fix locking for postbufq when freeing lpfc: Fix locking for lpfc_hba_down_post lpfc: Fix dynamic transitions of FirstBurst from on to off hpsa: fix handling of hpsa_volume_offline return value hpsa: return -ENOMEM not -1 on kzalloc failure in hpsa_get_device_id hpsa: remove messages about volume status VPD inquiry page not supported ...
2014-06-14Merge branch 'for-linus' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs Pull more btrfs updates from Chris Mason: "This has a few fixes since our last pull and a new ioctl for doing btree searches from userland. It's very similar to the existing ioctl, but lets us return larger items back down to the app" * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs: btrfs: fix error handling in create_pending_snapshot btrfs: fix use of uninit "ret" in end_extent_writepage() btrfs: free ulist in qgroup_shared_accounting() error path Btrfs: fix qgroups sanity test crash or hang btrfs: prevent RCU warning when dereferencing radix tree slot Btrfs: fix unfinished readahead thread for raid5/6 degraded mounting btrfs: new ioctl TREE_SEARCH_V2 btrfs: tree_search, search_ioctl: direct copy to userspace btrfs: new function read_extent_buffer_to_user btrfs: tree_search, copy_to_sk: return needed size on EOVERFLOW btrfs: tree_search, copy_to_sk: return EOVERFLOW for too small buffer btrfs: tree_search, search_ioctl: accept varying buffer btrfs: tree_search: eliminate redundant nr_items check
2014-06-14Merge git://git.kvack.org/~bcrl/aio-nextLinus Torvalds
Pull aio fix and cleanups from Ben LaHaise: "This consists of a couple of code cleanups plus a minor bug fix" * git://git.kvack.org/~bcrl/aio-next: aio: cleanup: flatten kill_ioctx() aio: report error from io_destroy() when threads race in io_destroy() fs/aio.c: Remove ctx parameter in kiocb_cancel
2014-06-14fix __swap_writepage() compile failure on old gcc versionsAl Viro
Tetsuo Handa wrote: "Commit 62a8067a7f35 ("bio_vec-backed iov_iter") introduced an unnamed union inside a struct which gcc-4.4.7 cannot handle. Name the unnamed union as u in order to fix build failure" Let's do this instead: there is only one place in the entire tree that steps into this breakage. Anon structs and unions work in older gcc versions; as the matter of fact, we have those in the tree - see e.g. struct ieee80211_tx_info in include/net/mac80211.h What doesn't work is handling their initializers: struct { int a; union { int b; char c; }; } x[2] = {{.a = 1, .c = 'a'}, {.a = 0, .b = 1}}; is the obvious syntax for initializer, perfectly fine for C11 and handled correctly by gcc-4.7 or later. Earlier versions, though, break on it - declaration is fine and so's access to fields (i.e. x[0].c = 'a'; would produce the right code), but members of the anon structs and unions are not inserted into the right namespace. Tellingly, those older versions will not barf on struct {int a; struct {int a;};}; - looks like they just have it hacked up somewhere around the handling of . and -> instead of doing the right thing. The easiest way to deal with that crap is to turn initialization of those fields (in the only place where we have such initializer of iov_iter) into plain assignment. Reported-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Reported-by: Russell King <rmk+kernel@arm.linux.org.uk> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-14Merge tag 'hsi-for-3.16-fixes1' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/sre/linux-hsi Pull HSI build fixes from Sebastian Reichel: - tighten dependency between ssi-protocol and omap-ssi to fix build failures with randconfig. - use normal module refcounting in omap driver to fix build with disabled module support * tag 'hsi-for-3.16-fixes1' of git://git.kernel.org/pub/scm/linux/kernel/git/sre/linux-hsi: hsi: omap_ssi_port: use normal module refcounting HSI: fix omap ssi driver dependency