- 21 Feb, 2012 31 commits
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Paul E. McKenney authored
The torture.txt documentation gives an example rcutorture run with a 100-second duration. This is ridiculously short, unless maybe testing a fix for a egregious bug. Use a more-realistic one-hour duration for the example. Signed-off-by:Paul E. McKenney <paulmck@linux.vnet.ibm.com>
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Paul E. McKenney authored
When rcutorture is started automatically at boot time, it might well also start CPU-hotplug operations at that time, which might not be desirable. This commit therefore adds an rcutorture parameter that allows CPU-hotplug operations to be held off for the specified number of seconds after the start of boot. Signed-off-by:
Paul E. McKenney <paul.mckenney@linaro.org> Signed-off-by:
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Paul E. McKenney authored
There have been situations where RCU CPU stall warnings were caused by issues in scheduling-clock timer initialization. To make it easier to track these down, this commit causes the RCU CPU stall-warning messages to print out the number of scheduling-clock interrupts taken in the current grace period for each stalled CPU. Signed-off-by:
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Paul E. McKenney authored
The default CONFIG_RCU_CPU_STALL_TIMEOUT value of 60 seconds has served Linux users well for production use for quite some time. However, for debugging, there will be more than three minutes between subsequent stall-warning messages. This can be an annoyingly long wait if you are trying to work out where the offending infinite loop is hiding. Therefore, this commit provides a rcu_cpu_stall_timeout sysfs parameter that may be adjusted at boot time and at runtime to speed up debugging. Signed-off-by: -
Paul E. McKenney authored
Now that both TINY_RCU and TINY_PREEMPT_RCU have been in place for awhile, it is time to remove UP support from TREE_RCU, which is what this commit does. Signed-off-by:
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Paul E. McKenney authored
There is no convenient expression for rcu_deference_protected() when it is used in tearing down multilinked structures following a grace period. For example, suppose that an element containing an RCU-protected pointer to a second element is removed from an enclosing RCU-protected data structure, then the write-side lock is released, and finally synchronize_rcu() is invoked to wait for a grace period. Then it is necessary to traverse the pointer in order to free up the second element. But we are not in an RCU read-side critical section and we are holding no locks, so the usual rcu_dereference_check() and rcu_dereference_protected() primitives are not appropriate. Neither is rcu_dereference_raw(), as it is intended for use in data structures where the user defines the locking design (for example, list_head). So this responsibility is added to rcu_access_pointer()'s list, and this commit updates rcu_assign_pointer()'s header comment accordingly. Suggested-by:
David Howells <dhowells@redhat.com> Signed-off-by:
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Paul E. McKenney authored
Although it is OK to be preempted in an RCU read-side critical section for TREE_PREEMPT_RCU, it is definitely not OK to be preempted, block, or might_sleep() within an RCU read-side critical section for TREE_RCU. Unfortunately, rcu_might_sleep() currently only checks for RCU-bh and RCU-sched read-side critical sections. This commit therefore makes rcu_might_sleep() check for RCU read-side critical sections, but only in TREE_RCU builds. Signed-off-by:
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Paul E. McKenney authored
The inner idle loop is an extended quiescent state for all flavors of RCU, but there have been recent bug involving use of RCU read-side primitives from within the idle loop. Therefore, this commit enlists lockdep-RCU to detect attempts to enter the inner idle loop while in an RCU read-side critical section, emitting a lockdep-RCU splat if so. Signed-off-by:
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Paul E. McKenney authored
The recent updates to RCU_CPU_FAST_NO_HZ have an rcu_needs_cpu() that does more than just check for callbacks, so get the name for rcu_preempt_needs_cpu() consistent with that change, now calling it rcu_preempt_cpu_has_callbacks(). Signed-off-by:
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Paul E. McKenney authored
This is a port of commit #82e78d80 from TREE_PREEMPT_RCU to TINY_PREEMPT_RCU. This commit uses the fact that current->rcu_boost_mutex is set any time that the RCU_READ_UNLOCK_BOOSTED flag is set in the current->rcu_read_unlock_special bitmask. This allows tests of the bit to be changed to tests of the pointer, which in turn allows the RCU_READ_UNLOCK_BOOSTED flag to be eliminated. Please note that the check of current->rcu_read_unlock_special need not change because any time that RCU_READ_UNLOCK_BOOSTED was set, so was RCU_READ_UNLOCK_BLOCKED. Therefore, __rcu_read_unlock() can continue testing current->rcu_read_unlock_special for non-zero, as before. Signed-off-by:
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Paul E. McKenney authored
This is a port to TINY_RCU of Peter Zijlstra's commit #ec433f0c The rcu_read_unlock_special() function relies on in_irq() to exclude scheduler activity from interrupt level. This fails because exit_irq() can invoke the scheduler after clearing the preempt_count() bits that in_irq() uses to determine that it is at interrupt level. This situation can result in failures as follows: $task IRQ SoftIRQ rcu_read_lock() /* do stuff */ <preempt> |= UNLOCK_BLOCKED rcu_read_unlock() --t->rcu_read_lock_nesting irq_enter(); /* do stuff, don't use RCU */ irq_exit(); sub_preempt_count(IRQ_EXIT_OFFSET); invoke_softirq() ttwu(); spin_lock_irq(&pi->lock) rcu_read_lock(); /* do stuff */ rcu_read_unlock(); rcu_read_unlock_special() rcu_report_exp_rnp() ttwu() spin_lock_irq(&pi->lock) /* deadlock */ rcu_read_unlock_special(t); This can be triggered 'easily' because invoke_softirq() immediately does a ttwu() of ksoftirqd/# instead of doing the in-place softirq stuff first, but even without that the above happens. Cure this by also excluding softirqs from the rcu_read_unlock_special() handler and ensuring the force_irqthreads ksoftirqd/# wakeup is done from full softirq context. It is also necessary to delay the ->rcu_read_lock_nesting decrement until after rcu_read_unlock_special(). This delay is handled by the commit "Protect __rcu_read_unlock() against scheduler-using irq handlers". Signed-off-by:
Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by:
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Paul E. McKenney authored
This is a port of commit #b0d30417 from TREE_RCU to TREE_PREEMPT_RCU. Under some rare but real combinations of configuration parameters, RCU callbacks are posted during early boot that use kernel facilities that are not yet initialized. Therefore, when these callbacks are invoked, hard hangs and crashes ensue. This commit therefore prevents RCU callbacks from being invoked until after the scheduler is fully up and running, as in after multiple tasks have been spawned. It might well turn out that a better approach is to identify the specific RCU callbacks that are causing this problem, but that discussion will wait until such time as someone really needs an RCU callback to be invoked (as opposed to merely registered) during early boot. Signed-off-by:
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Paul E. McKenney authored
This is a port of commit #be0e1e21 to TINY_PREEMPT_RCU. This uses noinline to prevent rcu_read_unlock_special() from being inlined into __rcu_read_unlock(). Signed-off-by:
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Paul E. McKenney authored
This commit ports commit #10f39bb1 (rcu: protect __rcu_read_unlock() against scheduler-using irq handlers) from TREE_PREEMPT_RCU to TINY_PREEMPT_RCU. The following is a corresponding port of that commit message. The addition of RCU read-side critical sections within runqueue and priority-inheritance critical sections introduced some deadlocks, for example, involving interrupts from __rcu_read_unlock() where the interrupt handlers call wake_up(). This situation can cause the instance of __rcu_read_unlock() invoked from interrupt to do some of the processing that would otherwise have been carried out by the task-level instance of __rcu_read_unlock(). When the interrupt-level instance of __rcu_read_unlock() is called with a scheduler lock held from interrupt-entry/exit situations where in_irq() returns false, deadlock can result. Of course, in a UP kernel, there are not really any deadlocks, but the upper-level critical section can still be be fatally confused by the lower-level critical section changing things out from under it. This commit resolves these deadlocks by using negative values of the per-task ->rcu_read_lock_nesting counter to indicate that an instance of __rcu_read_unlock() is in flight, which in turn prevents instances from interrupt handlers from doing any special processing. Note that nested rcu_read_lock()/rcu_read_unlock() pairs are still permitted, but they will never see ->rcu_read_lock_nesting go to zero, and will therefore never invoke rcu_read_unlock_special(), thus preventing them from seeing the RCU_READ_UNLOCK_BLOCKED bit should it be set in ->rcu_read_unlock_special. This patch also adds a check for ->rcu_read_unlock_special being negative in rcu_check_callbacks(), thus preventing the RCU_READ_UNLOCK_NEED_QS bit from being set should a scheduling-clock interrupt occur while __rcu_read_unlock() is exiting from an outermost RCU read-side critical section. Of course, __rcu_read_unlock() can be preempted during the time that ->rcu_read_lock_nesting is negative. This could result in the setting of the RCU_READ_UNLOCK_BLOCKED bit after __rcu_read_unlock() checks it, and would also result it this task being queued on the corresponding rcu_node structure's blkd_tasks list. Therefore, some later RCU read-side critical section would enter rcu_read_unlock_special() to clean up -- which could result in deadlock (OK, OK, fatal confusion) if that RCU read-side critical section happened to be in the scheduler where the runqueue or priority-inheritance locks were held. To prevent the possibility of fatal confusion that might result from preemption during the time that ->rcu_read_lock_nesting is negative, this commit also makes rcu_preempt_note_context_switch() check for negative ->rcu_read_lock_nesting, thus refraining from queuing the task (and from setting RCU_READ_UNLOCK_BLOCKED) if we are already exiting from the outermost RCU read-side critical section (in other words, we really are no longer actually in that RCU read-side critical section). In addition, rcu_preempt_note_context_switch() invokes rcu_read_unlock_special() to carry out the cleanup in this case, which clears out the ->rcu_read_unlock_special bits and dequeues the task (if necessary), in turn avoiding needless delay of the current RCU grace period and needless RCU priority boosting. It is still illegal to call rcu_read_unlock() while holding a scheduler lock if the prior RCU read-side critical section has ever had both preemption and irqs enabled. However, the common use case is legal, namely where then entire RCU read-side critical section executes with irqs disabled, for example, when the scheduler lock is held across the entire lifetime of the RCU read-side critical section. Signed-off-by:
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Paul E. McKenney authored
The grace-period initialization sequence in rcu_start_gp() has a special case for systems where the rcu_node tree is a single rcu_node structure. This made sense some years ago when systems were smaller and up to 64 CPUs could share a single rcu_node structure, but now that large systems are common and a given leaf rcu_node structure can support only 16 CPUs (due to lock contention on the rcu_node's ->lock field), this optimization is almost never taken. And even the small mobile platforms that might make use of it might rather have the kernel text reduction. Therefore, this commit removes the check for single-rcu_node trees. Signed-off-by:
Josh Triplett <josh@joshtriplett.org>
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Paul E. McKenney authored
RCU's current CPU-offline code path dumps all of the outgoing CPU's callbacks onto the RCU_NEXT_TAIL portion of the surviving CPU's callback list. This means that all the ready-to-invoke callbacks from the outgoing CPU must wait for another full RCU grace period. This was just fine when CPU-hotplug events were rare, but there is increasing evidence that users are planning to make increasing use of CPU hotplug. Therefore, this commit changes the callback-dumping procedure so that callbacks that are ready to invoke are moved to the RCU_DONE_TAIL portion of the surviving CPU's callback list. This avoids running these callbacks through a second unnecessary grace period. Signed-off-by:
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Paul E. McKenney authored
Because quiescent states are now reported from offline CPUs in CPU_DYING state, there is some possibility that such a CPU might note the end of a grace period and attempt to start invoking callbacks. This would be a very bad thing, and is supposed to be prevented by the fact that the CPU_DYING CPU gets rid of all its callbacks before reporting the quiescent state. However, there is other CPU-offline code in the kernel, and it is quite possible that someone will invoke RCU core processing from that code. Therefore, this commit adds a warning for this case. Signed-off-by:
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Paul E. McKenney authored
Currently, a given CPU is permitted to remain in dyntick-idle mode indefinitely if it has only lazy RCU callbacks queued. This is vulnerable to corner cases in NUMA systems, so limit the time to six seconds by default. (Currently controlled by a cpp macro.) Signed-off-by:
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Paul E. McKenney authored
Make rcutorture check for CPU-hotplug failures and complain if there were any. Signed-off-by:
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Paul E. McKenney authored
Move ->qsmaskinit and blkd_tasks[] manipulation to the CPU_DYING notifier. This simplifies the code by eliminating a potential deadlock and by reducing the responsibilities of force_quiescent_state(). Also rename functions to make their connection to the CPU-hotplug stages explicit. Signed-off-by:
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Paul E. McKenney authored
The call_rcu() in mesh_gate_del() invokes mesh_gate_node_reclaim(), which simply calls kfree(). So convert the call_rcu() to kfree_rcu(), allowing mesh_gate_node_reclaim() to be eliminated. Signed-off-by:
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Paul E. McKenney authored
The call_rcu() in do_ip_setsockopt() invokes opt_kfree_rcu(), which just calls kfree(). So convert the call_rcu() to kfree_rcu(), which allows opt_kfree_rcu() to be eliminated. Signed-off-by:
David S. Miller <davem@davemloft.net> Cc: Alexey Kuznetsov <kuznet@ms2.inr.ac.ru> Cc: James Morris <jmorris@namei.org> Cc: Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org> Cc: Patrick McHardy <kaber@trash.net> Cc: netdev@vger.kernel.org
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Paul E. McKenney authored
Because opt_kfree_rcu() just calls kfree(), all call_rcu() uses of it may be converted to kfree_rcu(). This permits opt_kfree_rcu() to be eliminated. Signed-off-by:
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Paul E. McKenney authored
The call_rcu() in ft_tport_delete() invokes ft_tport_rcu_free(), which just does a kfree(). So convert the call_rcu() to kfree_rcu(), allowing ft_tport_rcu_free() to be eliminated. Signed-off-by:
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Paul E. McKenney authored
The call_rcu() in unregister_external_interrupt() invokes ext_int_hash_update(), which just does a kfree(). Convert the call_rcu() to kfree_rcu(), allowing ext_int_hash_update() to be eliminated. Signed-off-by:
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Paul E. McKenney authored
The RCU_TRACE kernel parameter has always been intended for debugging, not for production use. Formalize this by moving RCU_TRACE from init/Kconfig to lib/Kconfig.debug. Signed-off-by:
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Paul E. McKenney authored
When CONFIG_RCU_FAST_NO_HZ is enabled, RCU will allow a given CPU to enter dyntick-idle mode even if it still has RCU callbacks queued. RCU avoids system hangs in this case by scheduling a timer for several jiffies in the future. However, if all of the callbacks on that CPU are from kfree_rcu(), there is no reason to wake the CPU up, as it is not a problem to defer freeing of memory. This commit therefore tracks the number of callbacks on a given CPU that are from kfree_rcu(), and avoids scheduling the timer if all of a given CPU's callbacks are from kfree_rcu(). Signed-off-by:
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Paul E. McKenney authored
The push for energy efficiency will require that RCU tag rcu_head structures to indicate whether or not their invocation is time critical. This tagging is best carried out in the bottom bits of the ->next pointers in the rcu_head structures. This tagging requires that the rcu_head structures be properly aligned, so this commit adds the required diagnostics. Signed-off-by:
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Paul E. McKenney authored
It is illegal to have a grace period within a same-flavor RCU read-side critical section, so this commit adds lockdep-RCU checks to splat when such abuse is encountered. This commit does not detect more elaborate RCU deadlock situations. These situations might be a job for lockdep enhancements. Signed-off-by: -
Frederic Weisbecker authored
Although TREE_PREEMPT_RCU indirectly uses might_sleep() to detect illegal use of synchronize_sched() and synchronize_rcu_bh() from within an RCU read-side critical section, this might_sleep() check is bypassed when there is only a single CPU (for example, when running an SMP kernel on a single-CPU system). This patch therefore adds a might_sleep() call to the rcu_blocking_is_gp() check that is unconditionally invoked from both synchronize_sched() and synchronize_rcu_bh(). Signed-off-by:
Frederic Weisbecker <fweisbec@gmail.com> Signed-off-by:
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Paul E. McKenney authored
Add publications from 2010 and 2011 to RTFP.txt. Signed-off-by:
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- 18 Feb, 2012 9 commits
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Linus Torvalds authored
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git://git.kernel.org/pub/scm/linux/kernel/git/arm/arm-socLinus Torvalds authored
These are the bug fixes that have accumulated since 3.3-rc3 in arm-soc. The majority of them are regression fixes for stuff that broke during the merge 3.3 window. The notable ones are: * The at91 ata drivers both broke because of an earlier cleanup patch that some other patches were based on. Jean-Christophe decided to remove the legacy at91_ide driver and fix the new-style at91-pata driver while keeping the cleanup patch. I almost rejected the patches for being too late and too big but in the end decided to accept them because they fix a regression. * A patch fixing build breakage from the sysdev-to-device conversion colliding with other changes touches a number of mach-s3c files. * b0654037 "ARM: orion: Fix Orion5x GPIO regression from MPP cleanup" is a mechanical change that unfortunately touches a lot of lines that should up in the diffstat. * tag 'fixes-3.3-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/arm/arm-soc: (28 commits) ARM: at91: drop ide driver in favor of the pata one pata/at91: use newly introduced SMC accessors ARM: at91: add accessor to manage SMC ARM: at91:rtc/rtc-at91sam9: ioremap register bank ARM: at91: USB AT91 gadget registration for module ep93xx: fix build of vision_ep93xx.c ARM: OMAP2xxx: PM: fix OMAP2xxx-specific UART idle bug in v3.3 ARM: orion: Fix USB phy for orion5x. ARM: orion: Fix Orion5x GPIO regression from MPP cleanup ARM: EXYNOS: Add cpu-offset property in gic device tree node ARM: EXYNOS: Bring exynos4-dt up to date ARM: OMAP3: cm-t35: fix section mismatch warning ARM: OMAP2: Fix the OMAP2 only build break seen with 2011+ ARM tool-chains ARM: tegra: paz00: fix wrong UART port on mini-pcie plug ARM: tegra: paz00: fix wrong SD1 power gpio i2c: tegra: Add devexit_p() for remove ARM: EXYNOS: Correct M-5MOLS sensor clock frequency on Universal C210 board ARM: EXYNOS: Correct framebuffer window size on Nuri board ARM: SAMSUNG: Fix missing api-change from subsys_interface change ARM: EXYNOS: Fix "warning: initialization from incompatible pointer type" ...
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git://git.kernel.org/pub/scm/linux/kernel/git/davem/netLinus Torvalds authored
1) VETH_INFO_PEER netlink attribute needs to have it's size validated, from Thomas Graf. 2) 'poll' module option of bnx2x driver crashes the machine, just remove it. From Michal Schmidt. 3) ks8851_mll driver reads the irq number from two places, but only initializes one of them, oops. Use only one location and fix this problem, from Jan Weitzel. 4) Fix buffer overrun and unicast sterring bugs in mellanox mlx4 driver, from Eugenia Emantayev. 5) Swapped kcalloc() args in RxRPC and mlx4, from Axel Lin. 6) PHY MDIO device name regression fixes from Florian Fainelli. 7) If the wake event IRQ line is different from the netdevice one, we have to properly route it to the stmmac interrupt handler. From Francesco Virlinzi. 8) Fix rwlock lock initialization ordering bug in mac80211, from Mohammed Shafi Shajakhan. 9) TCP lost_cnt can get out of sync, and in fact go negative, in certain circumstances. Fix the way we specify what sequence range to operate on in tcp_sacktag_one() to fix this bug. From Neal Cardwell. * git://git.kernel.org/pub/scm/linux/kernel/git/davem/net: (27 commits) net/ethernet: ks8851_mll fix irq handling veth: Enforce minimum size of VETH_INFO_PEER stmmac: update the driver version to Feb 2012 (v2) stmmac: move hw init in the probe (v2) stmmac: request_irq when use an ext wake irq line (v2) stmmac: do not discard frame on dribbling bit assert ipheth: Add iPhone 4S mlx4: add unicast steering entries to resource_tracker mlx4: fix QP tree trashing mlx4: fix buffer overrun 3c59x: shorten timer period for slave devices netpoll: netpoll_poll_dev() should access dev->flags RxRPC: Fix kcalloc parameters swapped bnx2x: remove the 'poll' module option tcp: fix tcp_shifted_skb() adjustment of lost_cnt_hint for FACK ks8851: Fix NOHZ local_softirq_pending 08 warning bnx2x: fix bnx2x_storm_stats_update() on big endian ixp4xx-eth: fix PHY name to match MDIO bus name octeon: fix PHY name to match MDIO bus name fec: fix PHY name to match fixed MDIO bus name ...
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git://git.kernel.org/pub/scm/linux/kernel/git/broonie/regmapLinus Torvalds authored
Fixes a bootstrapping issue for some registers when a less commonly used method for register cache initialisation is used. Only affects a fairly small proportion of users that both don't use explicit register defaults and do use the cache. * tag 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/broonie/regmap: regmap: Fix cache defaults initialization from raw cache defaults
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Linus Torvalds authored
Merge tag 'ecryptfs-3.3-rc4-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tyhicks/ecryptfs Fixes maximum filename length and filesystem type reporting in statfs() calls and also fixes stale inode mode bits on eCryptfs inodes after a POSIX ACL was set on the lower filesystem's inode. * tag 'ecryptfs-3.3-rc4-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tyhicks/ecryptfs: ecryptfs: remove the second argument of k[un]map_atomic() eCryptfs: Copy up lower inode attrs after setting lower xattr eCryptfs: Improve statfs reporting
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git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-pinctrlLinus Torvalds authored
pinctrl fixes for v3.3 * tag 'pinctrl-for-torvalds-20120216' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-pinctrl: pinctrl: restore pin naming
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git://git.kernel.org/pub/scm/linux/kernel/git/benh/powerpcLinus Torvalds authored
Here are a few more fixes for powerpc. Some are regressions, the rest is simple/obvious/nasty enough that I deemed it good to go now. Here's also step one of deprecating legacy iSeries support: we are removing it from the main defconfig. Nobody seems to be using it anymore and the code is nasty to maintain, (involves horrible hacks in various low level areas of the kernel) so we plan to actually rip it out at some point. For now let's just avoid building it by default. Stephen will proceed to do the actual removal later (probably 3.4 or 3.5). * 'merge' of git://git.kernel.org/pub/scm/linux/kernel/git/benh/powerpc: powerpc/perf: power_pmu_start restores incorrect values, breaking frequency events powerpc/adb: Use set_current_state() powerpc: Disable interrupts early in Program Check powerpc: Remove legacy iSeries from ppc64_defconfig powerpc/fsl/pci: Fix PCIe fixup regression powerpc: Fix kernel log of oops/panic instruction dump
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git://git.kernel.org/pub/scm/linux/kernel/git/jbarnes/pciLinus Torvalds authored
One regression fix for SR-IOV on PPC and a couple of misc fixes from Yinghai. * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jbarnes/pci: PCI: Fix pci cardbus removal PCI: set pci sriov page size before reading SRIOV BAR PCI: workaround hard-wired bus number V2
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git://people.freedesktop.org/~airlied/linuxLinus Torvalds authored
3 radeon fixes, I have some exynos fixes to push later but I'll queue them separately once I've looked them over a bit. * 'drm-fixes' of git://people.freedesktop.org/~airlied/linux: drm/radeon/kms: fix MSI re-arm on rv370+ drm/radeon/kms/atom: bios scratch reg handling updates drm/radeon/kms: drop lock in return path of radeon_fence_count_emitted.
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