- 19 May, 2015 31 commits
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Luca Abeni authored
Add a description of the Dhall's effect, some discussion about schedulability tests for global EDF, and references to real-time literature. Signed-off-by:
Luca Abeni <luca.abeni@unitn.it> Signed-off-by:
Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: henrik@austad.us Cc: juri.lelli@gmail.com Cc: raistlin@linux.it Link: http://lkml.kernel.org/r/1431954032-16473-8-git-send-email-luca.abeni@unitn.itSigned-off-by:
Ingo Molnar <mingo@kernel.org>
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Luca Abeni authored
Add a short discussion about sufficient and necessary schedulability tests, and add a simple example showing that if D_i != P_i then density based tests are only sufficient. Also add some references to scientific papers on schedulability tests for EDF that are both necessary and sufficient, and on their computational complexity. Signed-off-by:
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Luca Abeni authored
The "_i" index is used in this document to to denote a particular task, so "sum_i", "max_i" and "min_i" might be confusing. Signed-off-by:
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Luca Abeni authored
The name "C_i" was used (without previously defining it) instead of "WCET_i". Signed-off-by:
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Luca Abeni authored
Signed-off-by:
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Luca Abeni authored
This file previously mixed American and British English; switch to American for consistency. Signed-off-by:
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Zhiqiang Zhang authored
C_i/min{D_i,T_i}, where T_i is not referred before, should be substituted with C_i/min{D_i,P_i}. Signed-off-by:Zhiqiang Zhang <zhangzhiqiang.zhang@huawei.com> Signed-off-by:
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Rik van Riel authored
It is possible for fbq_classify_rq() to indicate that a CPU has tasks that should be moved to another NUMA node, but for migrate_improves_locality and migrate_degrades_locality to not identify those tasks. This patch always gives preference to preferred node evaluations, and only checks the number of faults when evaluating moves between two non-preferred nodes on a larger NUMA system. On a two node system, the number of faults is never evaluated. Either a task is about to be pulled off its preferred node, or migrated onto it. Signed-off-by:
Rik van Riel <riel@redhat.com> Signed-off-by:
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Peter Zijlstra authored
Currently people use TASK_INTERRUPTIBLE to idle kthreads and wait for 'work' because TASK_UNINTERRUPTIBLE contributes to the loadavg. Having all idle kthreads contribute to the loadavg is somewhat silly. Now mostly this works OK, because kthreads have all their signals masked. However there's a few sites where this is causing problems and TASK_UNINTERRUPTIBLE should be used, except for that loadavg issue. This patch adds TASK_NOLOAD which, when combined with TASK_UNINTERRUPTIBLE avoids the loadavg accounting. As most of imagined usage sites are loops where a thread wants to idle, waiting for work, a helper TASK_IDLE is introduced. Signed-off-by:
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David Hildenbrand authored
As the fault handlers now all rely on the pagefault_disabled() checks and implicit preempt_disable() calls by pagefault_disable() have been made explicit, we can completely rely on the pagefault_disableD counter. So let's no longer touch the preempt count when disabling/enabling pagefaults. After a call to pagefault_disable(), pagefault_disabled() will return true, but in_atomic() won't. Reviewed-and-tested-by:
Thomas Gleixner <tglx@linutronix.de> Signed-off-by:
David Hildenbrand <dahi@linux.vnet.ibm.com> Signed-off-by:
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David Hildenbrand authored
Let's always disable preemption and pagefaults when locking the fpu, so we can be sure that the owner won't change in between. This is a preparation for pagefault_disable() not touching preemption anymore. Reviewed-and-tested-by:
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David Hildenbrand authored
enable_kernel_altivec() has to be called with disabled preemption. Let's make this explicit, to prepare for pagefault_disable() not touching preemption anymore. Reviewed-and-tested-by:
Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: David.Laight@ACULAB.COM Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: airlied@linux.ie Cc: akpm@linux-foundation.org Cc: bigeasy@linutronix.de Cc: borntraeger@de.ibm.com Cc: daniel.vetter@intel.com Cc: heiko.carstens@de.ibm.com Cc: herbert@gondor.apana.org.au Cc: hocko@suse.cz Cc: hughd@google.com Cc: mst@redhat.com Cc: paulus@samba.org Cc: ralf@linux-mips.org Cc: schwidefsky@de.ibm.com Cc: yang.shi@windriver.com Link: http://lkml.kernel.org/r/1431359540-32227-14-git-send-email-dahi@linux.vnet.ibm.comSigned-off-by:
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David Hildenbrand authored
As arm64 and arc have no special implementations for !CONFIG_SMP, mutual exclusion doesn't seem to rely on preemption. Let's make it clear in the comments that preemption doesn't have to be disabled when accessing user space in the futex code, so we can remove preempt_disable() from pagefault_disable(). Reviewed-and-tested-by:
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David Hildenbrand authored
The !CONFIG_SMP implementation of futex_atomic_op_inuser() seems to rely on disabled preemption to guarantee mutual exclusion. From commit e589ed23 ("[ARM] 5218/1: arm: improved futex support"): "For UP it's enough to disable preemption to ensure mutual exclusion..." From the code itself: "!SMP, we can work around lack of atomic ops by disabling preemption" Let's make this explicit, to prepare for pagefault_disable() not touching preemption anymore. Reviewed-and-tested-by:
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David Hildenbrand authored
The !CONFIG_SMP implementation of futex_atomic_cmpxchg_inatomic() requires preemption to be disabled to guarantee mutual exclusion. Let's make this explicit. This patch is based on a patch by Sebastian Andrzej Siewior on the -rt branch. Reviewed-and-tested-by:
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David Hildenbrand authored
Let's explicitly disable/enable preemption in the !CONFIG_SMP version of futex_atomic_cmpxchg_inatomic(), to prepare for pagefault_disable() not touching preemption anymore. This is needed for this function to be callable from both, atomic and non-atomic context. Otherwise we might break mutual exclusion when relying on a get_user()/ put_user() implementation. Reviewed-and-tested-by:
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David Hildenbrand authored
Let's explicitly disable/enable preemption in the !CONFIG_SMP version of futex_atomic_op_inuser, to prepare for pagefault_disable() not touching preemption anymore. Otherwise we might break mutual exclusion when relying on a get_user()/ put_user() implementation. Reviewed-and-tested-by:
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David Hildenbrand authored
Now that the pagefault disabled counter is in place, we can replace the in_atomic() check by a pagefault_disabled() checks. Reviewed-and-tested-by:
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David Hildenbrand authored
Introduce faulthandler_disabled() and use it to check for irq context and disabled pagefaults (via pagefault_disable()) in the pagefault handlers. Please note that we keep the in_atomic() checks in place - to detect whether in irq context (in which case preemption is always properly disabled). In contrast, preempt_disable() should never be used to disable pagefaults. With !CONFIG_PREEMPT_COUNT, preempt_disable() doesn't modify the preempt counter, and therefore the result of in_atomic() differs. We validate that condition by using might_fault() checks when calling might_sleep(). Therefore, add a comment to faulthandler_disabled(), describing why this is needed. faulthandler_disabled() and pagefault_disable() are defined in linux/uaccess.h, so let's properly add that include to all relevant files. This patch is based on a patch from Thomas Gleixner. Reviewed-and-tested-by:
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David Hildenbrand authored
k(un)map_coherent relies on pagefault_disable() to also disable preemption. Let's make this explicit, to prepare for pagefault_disable() not touching preemption anymore. This patch is based on a patch by Yang Shi on the -rt tree: "k{un}map_coherent are just called when cpu_has_dc_aliases == 1 with VIPT cache. However, actually, the most modern MIPS processors have PIPT dcache without dcache alias issue. In such case, k{un}map_atomic will be called with preempt enabled." Reviewed-and-tested-by: -
David Hildenbrand authored
The existing code relies on pagefault_disable() implicitly disabling preemption, so that no schedule will happen between kmap_atomic() and kunmap_atomic(). Let's make this explicit, to prepare for pagefault_disable() not touching preemption anymore. Reviewed-and-tested-by:
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David Hildenbrand authored
In general, non-atomic variants of user access functions must not sleep if pagefaults are disabled. Let's update all relevant comments in uaccess code. This also reflects the might_sleep() checks in might_fault(). Reviewed-and-tested-by:
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David Hildenbrand authored
Commit 662bbcb2 ("mm, sched: Allow uaccess in atomic with pagefault_disable()") removed might_sleep() checks for all user access code (that uses might_fault()). The reason was to disable wrong "sleep in atomic" warnings in the following scenario: pagefault_disable() rc = copy_to_user(...) pagefault_enable() Which is valid, as pagefault_disable() increments the preempt counter and therefore disables the pagefault handler. copy_to_user() will not sleep and return an error code if a page is not available. However, as all might_sleep() checks are removed, CONFIG_DEBUG_ATOMIC_SLEEP would no longer detect the following scenario: spin_lock(&lock); rc = copy_to_user(...) spin_unlock(&lock) If the kernel is compiled with preemption turned on, preempt_disable() will make in_atomic() detect disabled preemption. The fault handler would correctly never sleep on user access. However, with preemption turned off, preempt_disable() is usually a NOP (with !CONFIG_PREEMPT_COUNT), therefore in_atomic() will not be able to detect disabled preemption nor disabled pagefaults. The fault handler could sleep. We really want to enable CONFIG_DEBUG_ATOMIC_SLEEP checks for user access functions again, otherwise we can end up with horrible deadlocks. Root of all evil is that pagefault_disable() acts almost as preempt_disable(), depending on preemption being turned on/off. As we now have pagefault_disabled(), we can use it to distinguish whether user acces functions might sleep. Convert might_fault() into a makro that calls __might_fault(), to allow proper file + line messages in case of a might_sleep() warning. Reviewed-and-tested-by:
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David Hildenbrand authored
Until now, pagefault_disable()/pagefault_enabled() used the preempt count to track whether in an environment with pagefaults disabled (can be queried via in_atomic()). This patch introduces a separate counter in task_struct to count the level of pagefault_disable() calls. We'll keep manipulating the preempt count to retain compatibility to existing pagefault handlers. It is now possible to verify whether in a pagefault_disable() envionment by calling pagefault_disabled(). In contrast to in_atomic() it will not be influenced by preempt_enable()/preempt_disable(). This patch is based on a patch from Ingo Molnar. Reviewed-and-tested-by:
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Frederic Weisbecker authored
Now that PREEMPT_ACTIVE implies PREEMPT_DISABLE_OFFSET, ignoring PREEMPT_ACTIVE from in_atomic() check isn't useful anymore. Signed-off-by:
Frederic Weisbecker <fweisbec@gmail.com> Signed-off-by:
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Frederic Weisbecker authored
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Frederic Weisbecker authored
__schedule() disables preemption and some of its callers (the preempt_schedule*() family) also set PREEMPT_ACTIVE. So we have two preempt_count() modifications that could be performed at once. Lets remove the preemption disablement from __schedule() and pull this responsibility to its callers in order to optimize preempt_count() operations in a single place. Suggested-by:
Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by:
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Frederic Weisbecker authored
"CHECK" suggests it's only used as a comparison mask. But now it's used further as a config-conditional preempt disabler offset. Lets disambiguate this name. Signed-off-by:
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Frederic Weisbecker authored
Adjust a few comments, and further integrate a few definitions after the dumb headers copy. Signed-off-by:
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Frederic Weisbecker authored
preempt_mask.h defines all the preempt_count semantics and related symbols: preempt, softirq, hardirq, nmi, preempt active, need resched, etc... preempt.h defines the accessors and mutators of preempt_count. But there is a messy dependency game around those two header files: * preempt_mask.h includes preempt.h in order to access preempt_count() * preempt_mask.h defines all preempt_count semantic and symbols except PREEMPT_NEED_RESCHED that is needed by asm/preempt.h Thus we need to define it from preempt.h, right before including asm/preempt.h, instead of defining it to preempt_mask.h with the other preempt_count symbols. Therefore the preempt_count semantics happen to be spread out. * We plan to introduce preempt_active_[enter,exit]() to consolidate preempt_schedule*() code. But we'll need to access both preempt_count mutators (preempt_count_add()) and preempt_count symbols (PREEMPT_ACTIVE, PREEMPT_OFFSET). The usual place to define preempt operations is in preempt.h but then we'll need symbols in preempt_mask.h which already includes preempt.h. So we end up with a ressource circle dependency. Lets merge preempt_mask.h into preempt.h to solve these dependency issues. This way we gather semantic symbols and operation definition of preempt_count in a single file. This is a dumb copy-paste merge. Further merge re-arrangments are performed in a subsequent patch to ease review. Signed-off-by:
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Ingo Molnar authored
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- 18 May, 2015 3 commits
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Linus Torvalds authored
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Peter Zijlstra authored
Two watchdog changes that came through different trees had a non conflicting conflict, that is, one changed the semantics of a variable but no actual code conflict happened. So the merge appeared fine, but the resulting code did not behave as expected. Commit 195daf66 ("watchdog: enable the new user interface of the watchdog mechanism") changes the semantics of watchdog_user_enabled, which thereafter is only used by the functions introduced by b3738d29 ("watchdog: Add watchdog enable/disable all functions"). There further appears to be a distinct lack of serialization between setting and using watchdog_enabled, so perhaps we should wrap the {en,dis}able_all() things in watchdog_proc_mutex. This patch fixes a s2r failure reported by Michal; which I cannot readily explain. But this does make the code internally consistent again. Reported-and-tested-by:
Michal Hocko <mhocko@suse.cz> Signed-off-by:
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git://git.infradead.org/linux-mtdLinus Torvalds authored
Pull MTD fixes from Brian Norris: "Two MTD fixes for 4.1: - readtest: the signal-handling code was clobbering the error codes we should be handling/reporting in this test, rendering it useless. Noticed by Coverity. - the common SPI NOR flash DT binding (merged for 4.1-rc1) is being revised, so let's change that before 4.1 is minted" * tag 'for-linus-20150516' of git://git.infradead.org/linux-mtd: Documentation: dt: mtd: replace "nor-jedec" binding with "jedec, spi-nor" mtd: readtest: don't clobber error reports
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- 17 May, 2015 5 commits
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Nicholas Mc Guire authored
static code checking was unhappy with: ./kernel/sched/fair.c:162 WARNING: return of wrong type int != unsigned int get_update_sysctl_factor() is declared to return int but is currently returning an unsigned int. The first few preprocessed lines are: static int get_update_sysctl_factor(void) { unsigned int cpus = ({ int __min1 = (cpumask_weight(cpu_online_mask)); int __min2 = (8); __min1 < __min2 ? __min1: __min2; }); unsigned int factor; The type used by min_t() should be 'unsigned int' and the return type of get_update_sysctl_factor() should also be 'unsigned int' as its call-site update_sysctl() is expecting 'unsigned int' and the values utilizing: 'factor' 'sysctl_sched_min_granularity' 'sched_nr_latency' 'sysctl_sched_wakeup_granularity' ... are also all 'unsigned int', plus cpumask_weight() is also returning 'unsigned int'. So the natural type to use around here is 'unsigned int'. ( Patch was compile tested with x86_64_defconfig + CONFIG_SCHED_DEBUG=y and the changed sections in kernel/sched/fair.i were reviewed. ) Signed-off-by:Nicholas Mc Guire <hofrat@osadl.org> [ Improved the changelog a bit. ] Cc: H. Peter Anvin <hpa@zytor.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1431716742-11077-1-git-send-email-hofrat@osadl.orgSigned-off-by:
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git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usbLinus Torvalds authored
Pull USB fixes from Greg KH: "Here are some USB fixes and new device ids for 4.1-rc4. All are pretty minor, and have been in linux-next successfully" * tag 'usb-4.1-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb: usb-storage: Add NO_WP_DETECT quirk for Lacie 059f:0651 devices Added another USB product ID for ELAN touchscreen quirks. xhci: gracefully handle xhci_irq dead device xhci: Solve full event ring by increasing TRBS_PER_SEGMENT to 256 xhci: fix isoc endpoint dequeue from advancing too far on transaction error usb: chipidea: debug: avoid out of bound read USB: visor: Match I330 phone more precisely USB: pl2303: Remove support for Samsung I330 USB: cp210x: add ID for KCF Technologies PRN device usb: gadget: remove incorrect __init/__exit annotations usb: phy: isp1301: work around tps65010 dependency usb: gadget: serial: fix re-ordering of tx data usb: gadget: hid: Fix static variable usage usb: gadget: configfs: Fix interfaces array NULL-termination usb: gadget: xilinx: fix devm_ioremap_resource() check usb: dwc3: dwc3-omap: correct the register macros
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git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/ttyLinus Torvalds authored
Pull tty/serial fixes from Greg KH: "Here's some TTY and serial driver fixes for reported issues. All of these have been in linux-next successfully" * tag 'tty-4.1-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty: pty: Fix input race when closing tty/n_gsm.c: fix a memory leak when gsmtty is removed Revert "serial/amba-pl011: Leave the TX IRQ alone when the UART is not open" serial: omap: Fix error handling in probe earlycon: Revert log warnings
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git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/stagingLinus Torvalds authored
Pull staging / IIO driver fixes from Greg KH: "Here's some staging and iio driver fixes to resolve a number of reported issues. All of these have been in linux-next for a while" * tag 'staging-4.1-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging: (31 commits) iio: light: hid-sensor-prox: Fix memory leak in probe() iio: adc: cc10001: Add delay before setting START bit iio: adc: cc10001: Fix regulator_get_voltage() return value check iio: adc: cc10001: Fix incorrect use of power-up/power-down register staging: gdm724x: Correction of variable usage after applying ALIGN() iio: adc: cc10001: Fix the channel number mapping staging: vt6655: lock MACvWriteBSSIDAddress. staging: vt6655: CARDbUpdateTSF bss timestamp correct tsf counter value. staging: vt6655: vnt_tx_packet Correct TX order of OWNED_BY_NIC staging: vt6655: Fix 80211 control and management status reporting. staging: vt6655: implement IEEE80211_TX_STAT_NOACK_TRANSMITTED staging: vt6655: device_free_tx_buf use only ieee80211_tx_status_irqsafe staging: vt6656: use ieee80211_tx_info to select packet type. staging: rtl8712: freeing an ERR_PTR staging: sm750: remove incorrect __exit annotation iio: kfifo: Set update_needed to false only if a buffer was allocated iio: mcp320x: Fix occasional incorrect readings iio: accel: mma9553: check input value for activity period iio: accel: mma9553: add enable channel for activity iio: accel: mma9551_core: prevent buffer overrun ...
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git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-miscLinus Torvalds authored
Pull char/misc fix from Greg KH: "Here is one fix, in the extcon subsystem, that resolves a reported issue. It's been in linux-next for a number of weeks now, sorry for not getting it to you sooner" * tag 'char-misc-4.1-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc: extcon: usb-gpio: register extcon device before IRQ registration
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- 16 May, 2015 1 commit
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git://git.kernel.org/pub/scm/linux/kernel/git/rw/umlLinus Torvalds authored
Pull UML hostfs fix from Richard Weinberger: "This contains a single fix for a regression introduced in 4.1-rc1" * 'for-linus-4.1-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/rw/uml: hostfs: Use correct mask for file mode
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