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2013-12-13X.509: Fix certificate gatheringDavid Howells
Fix the gathering of certificates from both the source tree and the build tree to correctly calculate the pathnames of all the certificates. The problem was that if the default generated cert, signing_key.x509, didn't exist then it would not have a path attached and if it did, it would have a path attached. This means that the contents of kernel/.x509.list would change between the first compilation in a directory and the second. After the second it would remain stable because the signing_key.x509 file exists. The consequence was that the kernel would get relinked unconditionally on the second recompilation. The second recompilation would also show something like this: X.509 certificate list changed CERTS kernel/x509_certificate_list - Including cert /home/torvalds/v2.6/linux/signing_key.x509 AS kernel/system_certificates.o LD kernel/built-in.o which is why the relink would happen. Unfortunately, it isn't a simple matter of just sticking a path on the front of the filename of the certificate in the build directory as make can't then work out how to build it. So the path has to be prepended to the name for sorting and duplicate elimination and then removed for the make rule if it is in the build tree. Reported-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: David Howells <dhowells@redhat.com>
2013-12-12rcu: Remove "extern" from function declarations in kernel/rcu/rcu.hTeodora Baluta
Function prototypes don't need to have the "extern" keyword since this is the default behavior. Its explicit use is redundant. This commit therefore removes them. Signed-off-by: Teodora Baluta <teobaluta@gmail.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2013-12-12rcu/torture: Dynamically allocate SRCU output buffer to avoid overflowChen Gang
If the rcutorture SRCU output exceeds 4096 bytes, for example, if you have more than about 75 CPUs, it will overflow the current statically allocated buffer. This commit therefore replaces this static buffer with a dynamically buffer whose size is based on the number of CPUs. Benefits: - Avoids both buffer overflow and output truncation. - Handles an arbitrarily large number of CPUs. - Straightforward implementation. Shortcomings: - Some memory is wasted: 1 cpu now comsumes 50 - 60 bytes, and this patch provides 200 bytes. Therefore, for 1K CPUs, roughly 100KB of memory will be wasted. However, the memory is freed immediately after printing, so this wastage should not be a problem in practice. Testing (Fedora16 2 CPUs, 2GB RAM x86_64): - as module, with/without "torture_type=srcu". - build-in not boot runnable, with/without "torture_type=srcu". - build-in let boot runnable, with/without "torture_type=srcu". Signed-off-by: Chen Gang <gang.chen@asianux.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2013-12-12rcu: Don't activate RCU core on NO_HZ_FULL CPUsPaul E. McKenney
Whenever a CPU receives a scheduling-clock interrupt, RCU checks to see if the RCU core needs anything from this CPU. If so, RCU raises RCU_SOFTIRQ to carry out any needed processing. This approach has worked well historically, but it is undesirable on NO_HZ_FULL CPUs. Such CPUs are expected to spend almost all of their time in userspace, so that scheduling-clock interrupts can be disabled while there is only one runnable task on the CPU in question. Unfortunately, raising any softirq has the potential to wake up ksoftirqd, which would provide the second runnable task on that CPU, preventing disabling of scheduling-clock interrupts. What is needed instead is for RCU to leave NO_HZ_FULL CPUs alone, relying on the grace-period kthreads' quiescent-state forcing to do any needed RCU work on behalf of those CPUs. This commit therefore refrains from raising RCU_SOFTIRQ on any NO_HZ_FULL CPUs during any grace periods that have been in effect for less than one second. The one-second limit handles the case where an inappropriate workload is running on a NO_HZ_FULL CPU that features lots of scheduling-clock interrupts, but no idle or userspace time. Reported-by: Mike Galbraith <bitbucket@online.de> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Tested-by: Mike Galbraith <bitbucket@online.de> Toasted-by: Frederic Weisbecker <fweisbec@gmail.com>
2013-12-12rcu: Warn on allegedly impossible rcu_read_unlock_special() from irqLai Jiangshan
After commit #10f39bb1b2c1 (rcu: protect __rcu_read_unlock() against scheduler-using irq handlers), it is no longer possible to enter the main body of rcu_read_lock_special() from an NMI, interrupt, or softirq handler. In theory, this implies that the check for "in_irq() || in_serving_softirq()" must always fail, so that in theory this check could be removed entirely. In practice, this commit wraps this condition with a WARN_ON_ONCE(). If this warning never triggers, then the condition will be removed entirely. [ paulmck: And one way of triggering the WARN_ON() is if a scheduling clock interrupt occurs in an RCU read-side critical section, setting RCU_READ_UNLOCK_NEED_QS, which is handled by rcu_read_unlock_special(). Updated this commit to return if only that bit was set. ] Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2013-12-12Merge tag 'keys-devel-20131210' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs Pull misc keyrings fixes from David Howells: "These break down into five sets: - A patch to error handling in the big_key type for huge payloads. If the payload is larger than the "low limit" and the backing store allocation fails, then big_key_instantiate() doesn't clear the payload pointers in the key, assuming them to have been previously cleared - but only one of them is. Unfortunately, the garbage collector still calls big_key_destroy() when sees one of the pointers with a weird value in it (and not NULL) which it then tries to clean up. - Three patches to fix the keyring type: * A patch to fix the hash function to correctly divide keyrings off from keys in the topology of the tree inside the associative array. This is only a problem if searching through nested keyrings - and only if the hash function incorrectly puts the a keyring outside of the 0 branch of the root node. * A patch to fix keyrings' use of the associative array. The __key_link_begin() function initially passes a NULL key pointer to assoc_array_insert() on the basis that it's holding a place in the tree whilst it does more allocation and stuff. This is only a problem when a node contains 16 keys that match at that level and we want to add an also matching 17th. This should easily be manufactured with a keyring full of keyrings (without chucking any other sort of key into the mix) - except for (a) above which makes it on average adding the 65th keyring. * A patch to fix searching down through nested keyrings, where any keyring in the set has more than 16 keyrings and none of the first keyrings we look through has a match (before the tree iteration needs to step to a more distal node). Test in keyutils test suite: http://git.kernel.org/cgit/linux/kernel/git/dhowells/keyutils.git/commit/?id=8b4ae963ed92523aea18dfbb8cab3f4979e13bd1 - A patch to fix the big_key type's use of a shmem file as its backing store causing audit messages and LSM check failures. This is done by setting S_PRIVATE on the file to avoid LSM checks on the file (access to the shmem file goes through the keyctl() interface and so is gated by the LSM that way). This isn't normally a problem if a key is used by the context that generated it - and it's currently only used by libkrb5. Test in keyutils test suite: http://git.kernel.org/cgit/linux/kernel/git/dhowells/keyutils.git/commit/?id=d9a53cbab42c293962f2f78f7190253fc73bd32e - A patch to add a generated file to .gitignore. - A patch to fix the alignment of the system certificate data such that it it works on s390. As I understand it, on the S390 arch, symbols must be 2-byte aligned because loading the address discards the least-significant bit" * tag 'keys-devel-20131210' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs: KEYS: correct alignment of system_certificate_list content in assembly file Ignore generated file kernel/x509_certificate_list security: shmem: implement kernel private shmem inodes KEYS: Fix searching of nested keyrings KEYS: Fix multiple key add into associative array KEYS: Fix the keyring hash function KEYS: Pre-clear struct key on allocation
2013-12-12futex: move user address verification up to common codeLinus Torvalds
When debugging the read-only hugepage case, I was confused by the fact that get_futex_key() did an access_ok() only for the non-shared futex case, since the user address checking really isn't in any way specific to the private key handling. Now, it turns out that the shared key handling does effectively do the equivalent checks inside get_user_pages_fast() (it doesn't actually check the address range on x86, but does check the page protections for being a user page). So it wasn't actually a bug, but the fact that we treat the address differently for private and shared futexes threw me for a loop. Just move the check up, so that it gets done for both cases. Also, use the 'rw' parameter for the type, even if it doesn't actually matter any more (it's a historical artifact of the old racy i386 "page faults from kernel space don't check write protections"). Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-12-12futex: fix handling of read-only-mapped hugepagesLinus Torvalds
The hugepage code had the exact same bug that regular pages had in commit 7485d0d3758e ("futexes: Remove rw parameter from get_futex_key()"). The regular page case was fixed by commit 9ea71503a8ed ("futex: Fix regression with read only mappings"), but the transparent hugepage case (added in a5b338f2b0b1: "thp: update futex compound knowledge") case remained broken. Found by Dave Jones and his trinity tool. Reported-and-tested-by: Dave Jones <davej@fedoraproject.org> Cc: stable@kernel.org # v2.6.38+ Acked-by: Thomas Gleixner <tglx@linutronix.de> Cc: Mel Gorman <mgorman@suse.de> Cc: Darren Hart <dvhart@linux.intel.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-12-12cgroup: fix missing unlock on error in cgroup_load_subsys()Wei Yongjun
Add the missing unlock before return from function cgroup_load_subsys() in the error handling case. Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn> Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2013-12-11perf: Optimize ring-buffer write by depending on control dependenciesPeter Zijlstra
Remove a full barrier from the ring-buffer write path by relying on a control dependency to order a LOAD -> STORE scenario. Cc: "Paul E. McKenney" <paulmck@us.ibm.com> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/n/tip-8alv40z6ikk57jzbaobnxrjl@git.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-12-11sched/fair: Rework sched_fair time accountingPeter Zijlstra
Christian suffers from a bad BIOS that wrecks his i5's TSC sync. This results in him occasionally seeing time going backwards - which crashes the scheduler ... Most of our time accounting can actually handle that except the most common one; the tick time update of sched_fair. There is a further problem with that code; previously we assumed that because we get a tick every TICK_NSEC our time delta could never exceed 32bits and math was simpler. However, ever since Frederic managed to get NO_HZ_FULL merged; this is no longer the case since now a task can run for a long time indeed without getting a tick. It only takes about ~4.2 seconds to overflow our u32 in nanoseconds. This means we not only need to better deal with time going backwards; but also means we need to be able to deal with large deltas. This patch reworks the entire code and uses mul_u64_u32_shr() as proposed by Andy a long while ago. We express our virtual time scale factor in a u32 multiplier and shift right and the 32bit mul_u64_u32_shr() implementation reduces to a single 32x32->64 multiply if the time delta is still short (common case). For 64bit a 64x64->128 multiply can be used if ARCH_SUPPORTS_INT128. Reported-and-Tested-by: Christian Engelmayer <cengelma@gmx.at> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Cc: fweisbec@gmail.com Cc: Paul Turner <pjt@google.com> Cc: Stanislaw Gruszka <sgruszka@redhat.com> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andrew Morton <akpm@linux-foundation.org> Link: http://lkml.kernel.org/r/20131118172706.GI3866@twins.programming.kicks-ass.net Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-12-11sched: Initialize power_orig for overlapping groupsPeter Zijlstra
Yinghai reported that he saw a /0 in sg_capacity on his EX parts. Make sure to always initialize power_orig now that we actually use it. Ideally build_sched_domains() -> init_sched_groups_power() would also initialize this; but for some yet unexplained reason some setups seem to miss updates there. Reported-by: Yinghai Lu <yinghai@kernel.org> Tested-by: Yinghai Lu <yinghai@kernel.org> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/n/tip-l8ng2m9uml6fhibln8wqpom7@git.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-12-10KEYS: correct alignment of system_certificate_list content in assembly fileHendrik Brueckner
Apart from data-type specific alignment constraints, there are also architecture-specific alignment requirements. For example, on s390 symbols must be on even addresses implying a 2-byte alignment. If the system_certificate_list_end symbol is on an odd address and if this address is loaded, the least-significant bit is ignored. As a result, the load_system_certificate_list() fails to load the certificates because of a wrong certificate length calculation. To be safe, align system_certificate_list on an 8-byte boundary. Also improve the length calculation of the system_certificate_list content. Introduce a system_certificate_list_size (8-byte aligned because of unsigned long) variable that stores the length. Let the linker calculate this size by introducing a start and end label for the certificate content. Signed-off-by: Hendrik Brueckner <brueckner@linux.vnet.ibm.com> Signed-off-by: David Howells <dhowells@redhat.com>
2013-12-10Ignore generated file kernel/x509_certificate_listRusty Russell
$ git status # On branch pending-rebases # Untracked files: # (use "git add <file>..." to include in what will be committed) # # kernel/x509_certificate_list nothing added to commit but untracked files present (use "git add" to track) $ Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> Signed-off-by: David Howells <dhowells@redhat.com>
2013-12-09rcu: Provide better diagnostics for blocking in RCU callback functionsPaul E. McKenney
Currently blocking in an RCU callback function will result in "scheduling while atomic", which could be triggered for any number of reasons. To aid debugging, this patch introduces a rcu_callback_map that is used to tie the inappropriate voluntary context switch back to the fact that the function is being invoked from within a callback. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2013-12-09rcu: Improve SRCU's grace-period commentsPaul E. McKenney
This commit documents the memory-barrier guarantees provided by synchronize_srcu() and call_srcu(). Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2013-12-09rcu: Fix CONFIG_RCU_FANOUT_EXACT for odd fanout/leaf valuesPaul E. McKenney
Each element of the rcu_state structure's ->levelspread[] array is intended to contain the per-level fanout, where the zero-th element corresponds to the root of the rcu_node tree, and the last element corresponds to the leaves. In the CONFIG_RCU_FANOUT_EXACT case, this means that the last element should be filled in from CONFIG_RCU_FANOUT_LEAF (or from the rcu_fanout_leaf boot parameter, if provided) and that the remaining elements should be filled in from CONFIG_RCU_FANOUT. Unfortunately, the current code in rcu_init_levelspread() takes the opposite approach, placing CONFIG_RCU_FANOUT_LEAF in the zero-th element and CONFIG_RCU_FANOUT in the remaining elements. For typical power-of-two values, this generates odd but functional rcu_node trees. However, other values, for example CONFIG_RCU_FANOUT=3 and CONFIG_RCU_FANOUT_LEAF=2, generate trees that can leave some CPUs out of the grace-period computation, resulting in too-short grace periods and therefore a broken RCU implementation. This commit therefore fixes rcu_init_levelspread() to set the last ->levelspread[] array element from CONFIG_RCU_FANOUT_LEAF and the remaining elements from CONFIG_RCU_FANOUT, thus generating the intended rcu_node trees. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2013-12-09rcu: Fix coccinelle warningsFengguang Wu
This commit fixes the following coccinelle warning: kernel/rcu/tree.c:712:9-10: WARNING: return of 0/1 in function 'rcu_lockdep_current_cpu_online' with return type bool Return statements in functions returning bool should use true/false instead of 1/0. Generated by: coccinelle/misc/boolreturn.cocci Signed-off-by: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2013-12-09posix-timers: Convert abuses of BUG_ON to WARN_ONFrederic Weisbecker
The posix cpu timers code makes a heavy use of BUG_ON() but none of these concern fatal issues that require to stop the machine. So let's just warn the user when some internal state slips out of our hands. Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Kosaki Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Andrew Morton <akpm@linux-foundation.org>
2013-12-09posix-timers: Remove remaining uses of tasklist_lockFrederic Weisbecker
The remaining uses of tasklist_lock were mostly about synchronizing against sighand modifications, getting coherent and safe group samples and also thread/process wide timers list handling. All of this is already safely synchronizable with the target's sighand lock. Let's use it on these places instead. Also update the comments about locking. Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Kosaki Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Andrew Morton <akpm@linux-foundation.org>
2013-12-09posix-timers: Use sighand lock instead of tasklist_lock on timer deletionFrederic Weisbecker
Timer deletion doesn't need the tasklist lock. We need to protect against: * concurrent access to the lists p->cputime_expires and p->sighand->cputime_expires * task reaping that may also delete the timer list entry * timer firing We already hold the timer lock which protects us against concurrent timer firing. The rest only need the targets sighand to be locked. So hold it and drop the use of tasklist_lock there. Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Kosaki Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Andrew Morton <akpm@linux-foundation.org>
2013-12-09posix-timers: Use sighand lock instead of tasklist_lock for task clock sampleFrederic Weisbecker
There is no need for the tasklist_lock just to take a process wide clock sample. All we need is to get a coherent sample that doesn't race with exit() and exec(): * exit() may be concurrently reaping a task and flushing its time * sighand is unstable under exit() and exec(), and the latter also result in group leader that can change To protect against these, locking the target's sighand is enough. Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Kosaki Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Andrew Morton <akpm@linux-foundation.org>
2013-12-09posix-timers: Consolidate posix_cpu_clock_get()Frederic Weisbecker
Consolidate the clock sampling common code used for both local and remote targets. Note that this introduces a tiny user ABI change: if a PID is passed to clock_gettime() along the clockid, we used to forbid a process wide clock sample when that PID doesn't belong to a group leader. Now after this patch we allow process wide clock samples if that PID belongs to the current task, even if the current task is not the group leader. But local process wide clock samples are allowed if PID == 0 (current task) even if the current task is not the group leader. So in the end this should be no big deal as this actually harmonize the behaviour when the remote sample is actually a local one. Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Kosaki Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Andrew Morton <akpm@linux-foundation.org>
2013-12-09posix-timers: Remove useless clock sample on timers cleanupFrederic Weisbecker
a0b2062b0904ef07944c4a6e4d0f88ee44f1e9f2 ("posix_timers: fix racy timer delta caching on task exit") forgot to remove the arguments used for timer caching. Fix this leftover. Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Kosaki Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Andrew Morton <akpm@linux-foundation.org>
2013-12-09posix-timers: Remove dead task special caseFrederic Weisbecker
Now that we've removed all the optimizations that could result in NULL timer's targets, we can remove all the associated special case handling. Also add some warnings on NULL targets to spot any possible leftover. Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Kosaki Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Andrew Morton <akpm@linux-foundation.org>
2013-12-09posix-timers: Cleanup reaped target handlingFrederic Weisbecker
When a timer's target is seen to be buried, for example on calls to timer_gettime(), the posix cpu timers code behaves a bit like a garbage collector and releases early the reference to the task. Then again, this optimization complicates the code for no much value: it's up to the user to release the timer and its associated ressources by calling timer_delete() after it buries the target tasks. Remove this to simplify the code. Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Kosaki Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Andrew Morton <akpm@linux-foundation.org>
2013-12-09posix-timers: Remove dead process posix cpu timers cachingFrederic Weisbecker
Now that we removed dead thread posix cpu timers caching, lets remove the dead process wide version. This caching is similar to the per thread version but it should be even more rare: * If the process id dead, we are not reading its timers status from a thread belonging to its group since they are all dead. So this caching only concern remote process timers reads. Now posix cpu timers using itimers or timer_settime() can't do remote process timers anyway so it's not even clear if there is actually a user for this caching. * Unlike per thread timers caching, this only applies to zombies targets. Buried targets' process wide timers return 0 values. But then again, timer_gettime() can't read remote process timers, so if the process is dead, there can't be any reader left anyway. Then again this caching seem to complicate the code for corner cases that are probably not worth it. So lets get rid of it. Also remove the sample snapshot on dying process timer that is now useless, as suggested by Kosaki. Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Kosaki Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Andrew Morton <akpm@linux-foundation.org>
2013-12-09posix-timers: Remove dead thread posix cpu timers cachingFrederic Weisbecker
When a task is exiting or has exited, its posix cpu timers don't tick anymore and won't elapse further. It's too late for them to expire. So any further call to timer_gettime() on these timers will return the same remaining expiry time. The current code optimize this by caching the remaining delta and storing it where we use to save the absolute expiration time. This way, the future calls to timer_gettime() won't need to compute the difference between the absolute expiration time and the current time anymore. Now this optimization doesn't seem to bring much value. Computing the timer remaining delta is not very costly. Fetching the timer value OTOH can be costly in two ways: * CPUCLOCK_SCHED read requires to lock the target's rq. But some optimizations are on the way to make task_sched_runtime() not holding the rq lock of a non-running target. * CPUCLOCK_VIRT/CPUCLOCK_PROF read simply consist in fetching current->utime/current->stime except when the system uses full dynticks cputime accounting. The latter requires a per task lock in order to correctly compute user and system time. But once the target is dead, this lock shouldn't be contended anyway. All in one this caching doesn't seem to be justified. Given that it complicates the code significantly for few wins, let's remove it on single thread timers. Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Kosaki Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Andrew Morton <akpm@linux-foundation.org>
2013-12-07PCI: Disable Bus Master only on kexec rebootKhalid Aziz
Add a flag to tell the PCI subsystem that kernel is shutting down in preparation to kexec a kernel. Add code in PCI subsystem to use this flag to clear Bus Master bit on PCI devices only in case of kexec reboot. This fixes a power-off problem on Acer Aspire V5-573G and likely other machines and avoids any other issues caused by clearing Bus Master bit on PCI devices in normal shutdown path. The problem was introduced by b566a22c2332 ("PCI: disable Bus Master on PCI device shutdown"). This patch is based on discussion at http://marc.info/?l=linux-pci&m=138425645204355&w=2 Link: https://bugzilla.kernel.org/show_bug.cgi?id=63861 Reported-by: Chang Liu <cl91tp@gmail.com> Signed-off-by: Khalid Aziz <khalid.aziz@oracle.com> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com> Acked-by: Konstantin Khlebnikov <koct9i@gmail.com> Cc: stable@vger.kernel.org # v3.5+
2013-12-06cgroup: remove for_each_root_subsys()Tejun Heo
After the previous patch which introduced for_each_css(), for_each_root_subsys() only has two users left. This patch replaces it with for_each_subsys() + explicit subsys_mask testing and remove for_each_root_subsys() along with cgroupfs_root->subsys_list handling. This patch doesn't introduce any behavior changes. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2013-12-06cgroup: implement for_each_css()Tejun Heo
There are enough places where css's of a cgroup are iterated, which currently uses for_each_root_subsys() + explicit cgroup_css(). This patch implements for_each_css() and replaces the above combination with it. This patch doesn't introduce any behavior changes. v2: Updated to apply cleanly on top of v2 of "cgroup: fix css leaks on online_css() failure" Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2013-12-06cgroup: factor out cgroup_subsys_state creation into create_css()Tejun Heo
Now that all opertations to create a css (cgroup_subsys_state) are collected into a single loop in cgroup_create(), it's easy to factor it out into its own function. Factor out css creation into create_css(). This makes the code easier to follow and will enable decoupling css creation from cgroup creation which is necessary for the planned unified hierarchy. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2013-12-06cgroup: combine css handling loops in cgroup_create()Tejun Heo
Now that css operations in cgroup_create() are back-to-back, there isn't much point in allocating css's in one loop and onlining them in another. Merge the two loops so that a css is allocated and onlined on each iteration. css_ar[] is no longer necessary and replaced with a single pointer. This also simplifies the error handling path. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2013-12-06cgroup: reorder operations in cgroup_create()Tejun Heo
cgroup_create() currently does the followings. 1. alloc cgroup 2. alloc css's 3. create the directory and commit to cgroup creation 4. online css's 5. create cgroup and css files The sequence performs allocations before other operations but it doesn't buy anything because each of the above steps may fail and should be unrollable. Reorganize the sequence such that cgroup operations are done before css operations. 1. alloc cgroup 2. create the directory and files and commit to cgroup creation 3. alloc css's 4. create files for and online css's This simplifies the code a bit and enables further simplification and separating out css creation from cgroup creation which is necessary for the planned unified hierarchy where css's will be created and destroyed dynamically across the lifetime of a cgroup. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2013-12-06cgroup: make for_each_subsys() useable under cgroup_root_mutexTejun Heo
We want to use for_each_subsys() in cgroupfs_root handling where only cgroup_root_mutex is held. The only way cgroup_subsys[] can change is through module load/unload, make cgroup_[un]load_subsys() grab cgroup_root_mutex too and update the lockdep annotation in for_each_subsys() to allow either cgroup_mutex or cgroup_root_mutex. * Lockdep annotation is moved from inner 'if' condition to outer 'for' init caluse. There's no reason to execute the assertion every loop. * Loop index @i is renamed to @ssid. Indices iterating through subsys will be [re]named to @ssid gradually. v2: cgroup_assert_mutex_or_root_locked() caused build failure if !CONFIG_LOCKEDP. Conditionalize its definition. The build failure was reported by kbuild test bot. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Cc: kbuild test robot <fengguang.wu@intel.com>
2013-12-06cgroup: css iterations and css_from_dir() are safe under cgroup_mutexTejun Heo
Currently, all css iterations and css_from_dir() require RCU read lock whether the caller is holding cgroup_mutex or not, which is unnecessarily restrictive. They are all safe to use under cgroup_mutex without holding RCU read lock. Factor out cgroup_assert_mutex_or_rcu_locked() from css_from_id() and apply it to all css iteration functions and css_from_dir(). v2: cgroup_assert_mutex_or_rcu_locked() definition doesn't need to be inside CONFIG_PROVE_RCU ifdef as rcu_lockdep_assert() is always defined and conditionalized. Move it outside of the ifdef block. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2013-12-06Merge branch 'for-3.13-fixes' into for-3.14Tejun Heo
Pulling in as patches depending on 266ccd505e8a ("cgroup: fix cgroup_create() error handling path") are scheduled. Signed-off-by: Tejun Heo <tj@kernel.org>
2013-12-06cgroup: fix cgroup_create() error handling pathTejun Heo
ae7f164a09 ("cgroup: move cgroup->subsys[] assignment to online_css()") moved cgroup->subsys[] assignements later in cgroup_create() but didn't update error handling path accordingly leading to the following oops and leaking later css's after an online_css() failure. The oops is from cgroup destruction path being invoked on the partially constructed cgroup which is not ready to handle empty slots in cgrp->subsys[] array. BUG: unable to handle kernel NULL pointer dereference at 0000000000000008 IP: [<ffffffff810eeaa8>] cgroup_destroy_locked+0x118/0x2f0 PGD a780a067 PUD aadbe067 PMD 0 Oops: 0000 [#1] SMP Modules linked in: CPU: 6 PID: 7360 Comm: mkdir Not tainted 3.13.0-rc2+ #69 Hardware name: task: ffff8800b9dbec00 ti: ffff8800a781a000 task.ti: ffff8800a781a000 RIP: 0010:[<ffffffff810eeaa8>] [<ffffffff810eeaa8>] cgroup_destroy_locked+0x118/0x2f0 RSP: 0018:ffff8800a781bd98 EFLAGS: 00010282 RAX: ffff880586903878 RBX: ffff880586903800 RCX: ffff880586903820 RDX: ffff880586903860 RSI: ffff8800a781bdb0 RDI: ffff880586903820 RBP: ffff8800a781bde8 R08: ffff88060e0b8048 R09: ffffffff811d7bc1 R10: 000000000000008c R11: 0000000000000001 R12: ffff8800a72286c0 R13: 0000000000000000 R14: ffffffff81cf7a40 R15: 0000000000000001 FS: 00007f60ecda57a0(0000) GS:ffff8806272c0000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000008 CR3: 00000000a7a03000 CR4: 00000000000007e0 Stack: ffff880586903860 ffff880586903910 ffff8800a72286c0 ffff880586903820 ffffffff81cf7a40 ffff880586903800 ffff88060e0b8018 ffffffff81cf7a40 ffff8800b9dbec00 ffff8800b9dbf098 ffff8800a781bec8 ffffffff810ef5bf Call Trace: [<ffffffff810ef5bf>] cgroup_mkdir+0x55f/0x5f0 [<ffffffff811c90ae>] vfs_mkdir+0xee/0x140 [<ffffffff811cb07e>] SyS_mkdirat+0x6e/0xf0 [<ffffffff811c6a19>] SyS_mkdir+0x19/0x20 [<ffffffff8169e569>] system_call_fastpath+0x16/0x1b This patch moves reference bumping inside online_css() loop, clears css_ar[] as css's are brought online successfully, and updates err_destroy path so that either a css is fully online and destroyed by cgroup_destroy_locked() or the error path frees it. This creates a duplicate css free logic in the error path but it will be cleaned up soon. v2: Li pointed out that cgroup_destroy_locked() would do NULL-deref if invoked with a cgroup which doesn't have all css's populated. Update cgroup_destroy_locked() so that it skips NULL css's. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Reported-by: Vladimir Davydov <vdavydov@parallels.com> Cc: stable@vger.kernel.org # v3.12+
2013-12-06Merge tag 'trace-fixes-3.13-rc2' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace Pull tracing fix from Steven Rostedt: "A regression showed up that there's a large delay when enabling all events. This was prevalent when FTRACE_SELFTEST was enabled which enables all events several times, and caused the system bootup to pause for over a minute. This was tracked down to an addition of a synchronize_sched() performed when system call tracepoints are unregistered. The synchronize_sched() is needed between the unregistering of the system call tracepoint and a deletion of a tracing instance buffer. But placing the synchronize_sched() in the unreg of *every* system call tracepoint is a bit overboard. A single synchronize_sched() before the deletion of the instance is sufficient" * tag 'trace-fixes-3.13-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: tracing: Only run synchronize_sched() at instance deletion time
2013-12-05tracing: Only run synchronize_sched() at instance deletion timeSteven Rostedt
It has been reported that boot up with FTRACE_SELFTEST enabled can take a very long time. There can be stalls of over a minute. This was tracked down to the synchronize_sched() called when a system call event is disabled. As the self tests enable and disable thousands of events, this makes the synchronize_sched() get called thousands of times. The synchornize_sched() was added with d562aff93bfb53 "tracing: Add support for SOFT_DISABLE to syscall events" which caused this regression (added in 3.13-rc1). The synchronize_sched() is to protect against the events being accessed when a tracer instance is being deleted. When an instance is being deleted all the events associated to it are unregistered. The synchronize_sched() makes sure that no more users are running when it finishes. Instead of calling synchronize_sched() for all syscall events, we only need to call it once, after the events are unregistered and before the instance is deleted. The event_mutex is held during this action to prevent new users from enabling events. Link: http://lkml.kernel.org/r/20131203124120.427b9661@gandalf.local.home Reported-by: Petr Mladek <pmladek@suse.cz> Acked-by: Tom Zanussi <tom.zanussi@linux.intel.com> Acked-by: Petr Mladek <pmladek@suse.cz> Tested-by: Petr Mladek <pmladek@suse.cz> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2013-12-05cgroup: unify pidlist and other file handlingTejun Heo
In preparation of conversion to kernfs, cgroup file handling is updated so that it can be easily mapped to kernfs. With the previous changes, the difference between pidlist and other files are very small. Both are served by seq_file in a pretty standard way with the only difference being !pidlist files use single_open(). This patch adds cftype->seq_start(), ->seq_next and ->seq_stop() and implements the matching cgroup_seqfile_start/next/stop() which either emulates single_open() behavior or invokes cftype->seq_*() operations if specified. This allows using single seq_operations for both pidlist and other files and makes cgroup_pidlist_operations and cgorup_pidlist_open() no longer necessary. As cgroup_pidlist_open() was the only user of cftype->open(), the method is dropped together. This brings cftype file interface very close to kernfs interface and mapping shouldn't be too difficult. Once converted to kernfs, most of the plumbing code including cgroup_seqfile_*() will be removed as kernfs provides those facilities. This patch does not introduce any behavior changes. v2: Refreshed on top of the updated "cgroup: introduce struct cgroup_pidlist_open_file". v3: Refreshed on top of the updated "cgroup: attach cgroup_open_file to all cgroup files". Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2013-12-05cgroup: replace cftype->read_seq_string() with cftype->seq_show()Tejun Heo
In preparation of conversion to kernfs, cgroup file handling is updated so that it can be easily mapped to kernfs. This patch replaces cftype->read_seq_string() with cftype->seq_show() which is not limited to single_open() operation and will map directcly to kernfs seq_file interface. The conversions are mechanical. As ->seq_show() doesn't have @css and @cft, the functions which make use of them are converted to use seq_css() and seq_cft() respectively. In several occassions, e.f. if it has seq_string in its name, the function name is updated to fit the new method better. This patch does not introduce any behavior changes. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Aristeu Rozanski <arozansk@redhat.com> Acked-by: Vivek Goyal <vgoyal@redhat.com> Acked-by: Michal Hocko <mhocko@suse.cz> Acked-by: Daniel Wagner <daniel.wagner@bmw-carit.de> Acked-by: Li Zefan <lizefan@huawei.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Ingo Molnar <mingo@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Balbir Singh <bsingharora@gmail.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Neil Horman <nhorman@tuxdriver.com>
2013-12-05cgroup: attach cgroup_open_file to all cgroup filesTejun Heo
In preparation of conversion to kernfs, cgroup file handling is updated so that it can be easily mapped to kernfs. This patch attaches cgroup_open_file, which used to be attached to pidlist files, to all cgroup files, introduces seq_css/cft() accessors to determine the cgroup_subsys_state and cftype associated with a given cgroup seq_file, exports them as public interface. This doesn't cause any behavior changes but unifies cgroup file handling across different file types and will help converting them to kernfs seq_show() interface. v2: Li pointed out that the original patch was using single_open_size() incorrectly assuming that the size param is private data size. Fix it by allocating @of separately and passing it to single_open() and explicitly freeing it in the release path. This isn't the prettiest but this path is gonna be restructured by the following patches pretty soon. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2013-12-05cgroup: generalize cgroup_pidlist_open_fileTejun Heo
In preparation of conversion to kernfs, cgroup file handling is updated so that it can be easily mapped to kernfs. This patch renames cgroup_pidlist_open_file to cgroup_open_file and updates it so that it only contains a field to identify the specific file, ->cfe, and an opaque ->priv pointer. When cgroup is converted to kernfs, this will be replaced by kernfs_open_file which contains about the same information. As whether the file is "cgroup.procs" or "tasks" should now be determined from cgroup_open_file->cfe, the cftype->private for the two files now carry the file type and cgroup_pidlist_start() reads the type through cfe->type->private. This makes the distinction between cgroup_tasks_open() and cgroup_procs_open() unnecessary. cgroup_pidlist_open() is now directly used as the open method. This patch doesn't make any behavior changes. v2: Refreshed on top of the updated "cgroup: introduce struct cgroup_pidlist_open_file". Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2013-12-05cgroup: unify read path so that seq_file is always usedTejun Heo
With the recent removal of cftype->read() and ->read_map(), only three operations are remaining, ->read_u64(), ->read_s64() and ->read_seq_string(). Currently, the first two are handled directly while the last is handled through seq_file. It is trivial to serve the first two through the seq_file path too. This patch restructures read path so that all operations are served through cgroup_seqfile_show(). This makes all cgroup files seq_file - single_open/release() are now used by default, cgroup_seqfile_operations is dropped, and cgroup_file_operations uses seq_read() for read. This simplifies the code and makes the read path easy to convert to use kernfs. Note that, while cgroup_file_operations uses seq_read() for read, it still uses generic_file_llseek() for seeking instead of seq_lseek(). This is different from cgroup_seqfile_operations but shouldn't break anything and brings the seeking behavior aligned with kernfs. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2013-12-05cgroup: unify cgroup_write_X64() and cgroup_write_string()Tejun Heo
cgroup_write_X64() and cgroup_write_string() both implement about the same buffering logic. Unify the two into cgroup_file_write() which always allocates dynamic buffer for simplicity and uses kstrto*() instead of simple_strto*(). This patch doesn't make any visible behavior changes except for possibly different error value from kstrsto*(). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2013-12-05cgroup: remove cftype->read(), ->read_map() and ->write()Tejun Heo
In preparation of conversion to kernfs, cgroup file handling is being consolidated so that it can be easily mapped to the seq_file based interface of kernfs. After recent updates, ->read() and ->read_map() don't have any user left and ->write() never had any user. Remove them. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2013-12-05cpuset: convert away from cftype->read()Tejun Heo
In preparation of conversion to kernfs, cgroup file handling is being consolidated so that it can be easily mapped to the seq_file based interface of kernfs. All users of cftype->read() can be easily served, usually better, by seq_file and other methods. Rename cpuset_common_file_read() to cpuset_common_read_seq_string() and convert it to use read_seq_string() interface instead. This not only simplifies the code but also makes it more versatile. Before, the file couldn't output if the result is longer than PAGE_SIZE. After the conversion, seq_file automatically grows the buffer until the output can fit. This patch doesn't make any visible behavior changes except for being able to handle output larger than PAGE_SIZE. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2013-12-05cgroup, sched: convert away from cftype->read_map()Tejun Heo
In preparation of conversion to kernfs, cgroup file handling is being consolidated so that it can be easily mapped to the seq_file based interface of kernfs. cftype->read_map() doesn't add any value and being replaced with ->read_seq_string(). Update cpu_stats_show() and cpuacct_stats_show() accordingly. This patch doesn't make any visible behavior changes. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org>
2013-12-05padata: Fix wrong usage of rcu_dereference()Mathias Krause
A kernel with enabled lockdep complains about the wrong usage of rcu_dereference() under a rcu_read_lock_bh() protected region. =============================== [ INFO: suspicious RCU usage. ] 3.13.0-rc1+ #126 Not tainted ------------------------------- linux/kernel/padata.c:115 suspicious rcu_dereference_check() usage! other info that might help us debug this: rcu_scheduler_active = 1, debug_locks = 1 1 lock held by cryptomgr_test/153: #0: (rcu_read_lock_bh){.+....}, at: [<ffffffff8115c235>] padata_do_parallel+0x5/0x270 Fix that by using rcu_dereference_bh() instead. Signed-off-by: Mathias Krause <minipli@googlemail.com> Acked-by: Steffen Klassert <steffen.klassert@secunet.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>