summaryrefslogtreecommitdiff
path: root/kernel
AgeCommit message (Collapse)Author
2011-02-02tracing: Replace trace_event struct array with pointer arraySteven Rostedt
Currently the trace_event structures are placed in the _ftrace_events section, and at link time, the linker makes one large array of all the trace_event structures. On boot up, this array is read (much like the initcall sections) and the events are processed. The problem is that there is no guarantee that gcc will place complex structures nicely together in an array format. Two structures in the same file may be placed awkwardly, because gcc has no clue that they are suppose to be in an array. A hack was used previous to force the alignment to 4, to pack the structures together. But this caused alignment issues with other architectures (sparc). Instead of packing the structures into an array, the structures' addresses are now put into the _ftrace_event section. As pointers are always the natural alignment, gcc should always pack them tightly together (otherwise initcall, extable, etc would also fail). By having the pointers to the structures in the section, we can still iterate the trace_events without causing unnecessary alignment problems with other architectures, or depending on the current behaviour of gcc that will likely change in the future just to tick us kernel developers off a little more. The _ftrace_event section is also moved into the .init.data section as it is now only needed at boot up. Suggested-by: David Miller <davem@davemloft.net> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Acked-by: David S. Miller <davem@davemloft.net> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2011-02-02genirq: Prevent irq storm on migrationThomas Gleixner
move_native_irq() masks and unmasks the interrupt line unconditionally, but the interrupt line might be masked due to a threaded oneshot handler in progress. Unmasking the line in that case can lead to interrupt storms. Observed on PREEMPT_RT. Originally-from: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: stable@kernel.org
2011-02-02posix clocks: Introduce dynamic clocksRichard Cochran
This patch adds support for adding and removing posix clocks. The clock lifetime cycle is patterned after usb devices. Each clock is represented by a standard character device. In addition, the driver may optionally implement custom character device operations. The posix clock and timer system calls listed below now work with dynamic posix clocks, as well as the traditional static clocks. The following system calls are affected: - clock_adjtime (brand new syscall) - clock_gettime - clock_getres - clock_settime - timer_create - timer_delete - timer_gettime - timer_settime [ tglx: Adapted to the posix-timer cleanup. Moved clock_posix_dynamic to posix-clock.c and made all referenced functions static ] Signed-off-by: Richard Cochran <richard.cochran@omicron.at> Acked-by: John Stultz <johnstul@us.ibm.com> LKML-Reference: <20110201134420.164172635@linutronix.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2011-02-02posix-timers: Cleanup namespaceThomas Gleixner
Rename register_posix_clock() to posix_timers_register_clock(). That's what the function really does. As a side effect this cleans up the posix_clock namespace for the upcoming dynamic posix_clock infrastructure. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Tested-by: Richard Cochran <richard.cochran@omicron.at> Cc: John Stultz <johnstul@us.ibm.com> LKML-Reference: <alpine.LFD.2.00.1102021222240.31804@localhost6.localdomain6>
2011-02-02posix-timers: Add support for fd based clocksRichard Cochran
Extend the negative clockids which are currently used by posix cpu timers to encode the PID with a file descriptor based type which encodes the fd in the upper bits. Originally-from: Richard Cochran <richard.cochran@omicron.at> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: John Stultz <johnstul@us.ibm.com> LKML-Reference: <20110201134420.062860200@linutronix.de>
2011-02-02posix-timers: Introduce a syscall for clock tuning.Richard Cochran
A new syscall is introduced that allows tuning of a POSIX clock. The new call, clock_adjtime, takes two parameters, the clock ID and a pointer to a struct timex. Any ADJTIMEX(2) operation may be requested via this system call, but various POSIX clocks may or may not support tuning. [ tglx: Adapted to the posix-timer cleanup series. Avoid copy_to_user in the error case ] Signed-off-by: Richard Cochran <richard.cochran@omicron.at> Acked-by: John Stultz <johnstul@us.ibm.com> LKML-Reference: <20110201134419.869804645@linutronix.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2011-02-02time: Splitout compat timex accessorsRichard Cochran
Split out the compat timex accessors into separate functions. Preparatory patch for a new syscall. [ tglx: Split that patch from Richards "posix-timers: Introduce a syscall for clock tuning.". Keeps the changes strictly separate ] Originally-from: Richard Cochran <richardcochran@gmail.com> Acked-by: John Stultz <johnstul@us.ibm.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> LKML-Reference: <20110201134419.772343089@linutronix.de>
2011-02-02ntp: Add ADJ_SETOFFSET mode bitRichard Cochran
This patch adds a new mode bit into the timex structure. When set, the bit instructs the kernel to add the given time value to the current time. Signed-off-by: Richard Cochran <richard.cochran@omicron.at> Acked-by: John Stultz <johnstul@us.ibm.com> LKML-Reference: <20110201134320.688829863@linutronix.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2011-02-02time: Introduce timekeeping_inject_offsetJohn Stultz
This adds a kernel-internal timekeeping interface to add or subtract a fixed amount from CLOCK_REALTIME. This makes it so kernel users or interfaces trying to do so do not have to read the time, then add an offset and then call settimeofday(), which adds some extra error in comparision to just simply adding the offset in the kernel timekeeping core. Signed-off-by: John Stultz <john.stultz@linaro.org> Signed-off-by: Richard Cochran <richard.cochran@omicron.at> LKML-Reference: <20110201134419.584311693@linutronix.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2011-02-02posix-timer: Update commentRichard Cochran
Pick the cleanup to the comment in posix-timers.c from Richards all in one conversion patch. Originally-from: Richard Cochran <richardcochran@gmail.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: John Stultz <johnstul@us.ibm.com> LKML-Reference: <20110201134419.487708516@linutronix.de>
2011-02-02posix-timers: Make posix-cpu-timers functions staticThomas Gleixner
All functions are accessed via clock_posix_cpu now. So make them static. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: John Stultz <johnstul@us.ibm.com> Tested-by: Richard Cochran <richard.cochran@omicron.at> LKML-Reference: <20110201134419.389755466@linutronix.de>
2011-02-02posix-timers: Remove CLOCK_DISPATCH leftoversThomas Gleixner
All users gone. Remove the cruft. Huge thanks to Richard Cochran who tackled that maze first. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: John Stultz <johnstul@us.ibm.com> Tested-by: Richard Cochran <richard.cochran@omicron.at> LKML-Reference: <20110201134419.294620613@linutronix.de>
2011-02-02posix-timers: Convert timer_delete() to clockid_to_kclock()Thomas Gleixner
Set the common function for CLOCK_MONOTONIC and CLOCK_REALTIME kclocks and use the new decoding function. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: John Stultz <johnstul@us.ibm.com> Tested-by: Richard Cochran <richard.cochran@omicron.at> LKML-Reference: <20110201134419.198999420@linutronix.de>
2011-02-02posix-timers: Convert timer_gettime() to clockid_to_kclock()Thomas Gleixner
Set the common function for CLOCK_MONOTONIC and CLOCK_REALTIME kclocks and use the new decoding function. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: John Stultz <johnstul@us.ibm.com> Tested-by: Richard Cochran <richard.cochran@omicron.at> LKML-Reference: <20110201134419.101243181@linutronix.de>
2011-02-02posix-timers: Convert timer_settime() to clockid_to_kclock()Thomas Gleixner
Set the common function for CLOCK_MONOTONIC and CLOCK_REALTIME kclocks and use the new decoding function. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: John Stultz <johnstul@us.ibm.com> Tested-by: Richard Cochran <richard.cochran@omicron.at> LKML-Reference: <20110201134419.001863714@linutronix.de>
2011-02-02posix-timers: Convert timer_create() to clockid_to_kclock()Thomas Gleixner
Setup timer_create for CLOCK_MONOTONIC and CLOCK_REALTIME kclocks and remove the no_timer_create() implementation. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: John Stultz <johnstul@us.ibm.com> Tested-by: Richard Cochran <richard.cochran@omicron.at> LKML-Reference: <20110201134418.903604289@linutronix.de>
2011-02-02posix-timers: Remove useless res field from k_clockThomas Gleixner
The res member of kclock is only used by mmtimer.c, but even there it contains redundant information. Remove the field and fixup mmtimer. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: John Stultz <johnstul@us.ibm.com> Tested-by: Richard Cochran <richard.cochran@omicron.at> LKML-Reference: <20110201134418.808714587@linutronix.de>
2011-02-02posix-timers: Convert clock_getres() to clockid_to_kclock()Thomas Gleixner
Use the new kclock decoding. Fixup the fallout in mmtimer.c Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: John Stultz <johnstul@us.ibm.com> Tested-by: Richard Cochran <richard.cochran@omicron.at> LKML-Reference: <20110201134418.709802797@linutronix.de>
2011-02-02posix-timers: Make clock_getres and clock_get mandatoryThomas Gleixner
Richard said: "I would think that we can require k_clocks to provide the read function. This could be checked and enforced in register_posix_clock()." Add checks for clock_getres and clock_get in the register function. Suggested-by: Richard Cochran <richardcochran@gmail.com> Cc: John Stultz <johnstul@us.ibm.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2011-02-02posix-timers: Convert clock_gettime() to clockid_to_kclock()Thomas Gleixner
Use the new kclock decoding mechanism and rename the misnomed common_clock_get() to posix_clock_realtime_get(). Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: John Stultz <johnstul@us.ibm.com> Tested-by: Richard Cochran <richard.cochran@omicron.at> LKML-Reference: <20110201134418.611097203@linutronix.de>
2011-02-02posix-timers: Convert clock_settime to clockid_to_kclock()Thomas Gleixner
Use the new kclock decoding function in clock_settime and cleanup all kclocks which use the default functions. Rename the misnomed common_clock_set() to posix_clock_realtime_set(). Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: John Stultz <johnstul@us.ibm.com> Tested-by: Richard Cochran <richard.cochran@omicron.at> LKML-Reference: <20110201134418.518851246@linutronix.de>
2011-02-02posix-cpu-timers: Remove the stub nanosleep functionsThomas Gleixner
CLOCK_THREAD_CPUTIME_ID implements stub functions for nanosleep and nanosleep_restart, which return -EINVAL. That return value is wrong. The correct return value is -ENOTSUP. Remove the stubs and let the new dispatch code return the correct error code. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: John Stultz <johnstul@us.ibm.com> Tested-by: Richard Cochran <richard.cochran@omicron.at> LKML-Reference: <20110201134418.422446502@linutronix.de>
2011-02-02posix-timers: Cleanup restart_block usageThomas Gleixner
posix timers still use the legacy arg0-arg3 members of restart_block. Use restart_block.nanosleep instead Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: John Stultz <johnstul@us.ibm.com> Tested-by: Richard Cochran <richard.cochran@omicron.at> LKML-Reference: <20110201134418.232288779@linutronix.de>
2011-02-02posix-timers: Convert clock_nanosleep_restart to clockid_to_kclock()Thomas Gleixner
Use the new kclock decoding function in clock_nanosleep_restart. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: John Stultz <johnstul@us.ibm.com> Tested-by: Richard Cochran <richard.cochran@omicron.at> LKML-Reference: <20110201134418.131263211@linutronix.de>
2011-02-02posix-timers: Convert clock_nanosleep to clockid_to_kclock()Thomas Gleixner
Use the new kclock decoding function in clock_nanosleep and cleanup all kclocks which use the default functions. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: John Stultz <johnstul@us.ibm.com> Tested-by: Richard Cochran <richard.cochran@omicron.at> LKML-Reference: <20110201134418.034175556@linutronix.de>
2011-02-02posix-timers: Introduce clockid_to_kclock()Thomas Gleixner
New function to find the kclock for a given clockid. Returns a pointer to clock_posix_cpu if clockid < 0. If clockid >= MAXCLOCK or if the clock_getres pointer is not set it returns NULL. For valid clocks it returns a pointer to the matching posix_clock. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: John Stultz <johnstul@us.ibm.com> Acked-by: Richard Cochran <richard.cochran@omicron.at> LKML-Reference: <20110201134417.938447839@linutronix.de>
2011-02-02posix-timers: Introduce clock_posix_cpuThomas Gleixner
The CLOCK_DISPATCH() macro is a horrible magic. We call common functions if a function pointer is not set. That's just backwards. To support dynamic file decriptor based clocks we need to cleanup that dispatch logic. Create a k_clock struct clock_posix_cpu which has all the posix-cpu-timer functions filled in. After the cleanup the functions can be made static. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: John Stultz <johnstul@us.ibm.com> Tested-by: Richard Cochran <richard.cochran@omicron.at> LKML-Reference: <20110201134417.841974553@linutronix.de>
2011-02-02posix-timers: Cleanup struct initializersThomas Gleixner
Cosmetic. No functional change Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: John Stultz <johnstul@us.ibm.com> Tested-by: Richard Cochran <richard.cochran@omicron.at> LKML-Reference: <20110201134417.745627057@linutronix.de>
2011-02-02posix-timers: Define nanosleep not supported error separateThomas Gleixner
Define the conditional nanosleep not supported error value outside of do_posix_clock_nonanosleep(). Preparatory patch for further cleanups. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: John Stultz <johnstul@us.ibm.com> Tested-by: Richard Cochran <richard.cochran@omicron.at> LKML-Reference: <20110201134417.643486574@linutronix.de>
2011-02-02time: Correct the *settime* parametersRichard Cochran
Both settimeofday() and clock_settime() promise with a 'const' attribute not to alter the arguments passed in. This patch adds the missing 'const' attribute into the various kernel functions implementing these calls. Signed-off-by: Richard Cochran <richard.cochran@omicron.at> Acked-by: John Stultz <johnstul@us.ibm.com> LKML-Reference: <20110201134417.545698637@linutronix.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2011-02-01security: remove unused security_sysctl hookLucian Adrian Grijincu
The only user for this hook was selinux. sysctl routes every call through /proc/sys/. Selinux and other security modules use the file system checks for sysctl too, so no need for this hook any more. Signed-off-by: Lucian Adrian Grijincu <lucian.grijincu@gmail.com> Signed-off-by: Eric Paris <eparis@redhat.com>
2011-02-01time: Fix legacy arch falloutThomas Gleixner
The xtime/dotimer cleanup broke architectures which do not implement clockevents. Time to send out another __do_IRQ threat. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reported-by: Ingo Molnar <mingo@elte.hu> Cc: Torben Hohn <torbenh@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: johnstul@us.ibm.com Cc: yong.zhang0@gmail.com Cc: hch@infradead.org LKML-Reference: <20110127145905.23248.30458.stgit@localhost> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-01-31time: Make do_timer() and xtime_lock local to kernel/time/Torben Hohn
All callers of do_timer() are converted to xtime_update(). The only users of xtime_lock are in kernel/time/. Make both local to kernel/time/ and remove them from the global header files. [ tglx: Reuse tick-internal.h instead of creating another local header file. Massaged changelog ] Signed-off-by: Torben Hohn <torbenh@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: johnstul@us.ibm.com Cc: yong.zhang0@gmail.com Cc: hch@infradead.org Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2011-01-31Merge branch 'tip/rtmutex' of ↵Thomas Gleixner
git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-2.6-trace into core/locking *git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-2.6-trace tip/rtmutex: rtmutex: Simplify PI algorithm and make highest prio task get lock
2011-01-31time: Provide xtime_update()Torben Hohn
xtime_update() takes xtime_lock write locked and calls do_timer(). Provided to replace the do_timer() calls in the architecture code. Signed-off-by: Torben Hohn <torbenh@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: johnstul@us.ibm.com Cc: yong.zhang0@gmail.com Cc: hch@infradead.org LKML-Reference: <20110127145910.23248.21379.stgit@localhost> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2011-01-31time: Remove unused __get_wall_to_monotonic()Thomas Gleixner
No users left. Remove it. Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2011-01-31time: Provide get_xtime_and_monotonic_offset()Torben Hohn
The hrtimer code accesses timekeeping variables under xtime_lock. Provide a sensible accessor function and use it. [ tglx: Removed the conditionals, unused variable, fixed codingstyle and massaged changelog ] Signed-off-by: Torben Hohn <torbenh@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: johnstul@us.ibm.com Cc: yong.zhang0@gmail.com Cc: hch@infradead.org LKML-Reference: <20110127145905.23248.30458.stgit@localhost> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2011-01-31time: Move get_jiffies_64 to kernel/time/jiffies.cTorben Hohn
Move the jiffies access functions to the jiffies clocksource code. [ tglx: Add missing include ] Signed-off-by: Torben Hohn <torbenh@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: johnstul@us.ibm.com Cc: yong.zhang0@gmail.com Cc: hch@infradead.org LKML-Reference: <20110127145900.23248.73352.stgit@localhost> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2011-01-31time: Move do_timer() to kernel/time/timekeeping.cTorben Hohn
do_timer() is primary timekeeping related. calc_global_load() is called from do_timer() as well, but that's more for historical reasons. [ tglx: Fixed up the calc_global_load() reject andmassaged changelog ] Signed-off-by: Torben Hohn <torbenh@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: johnstul@us.ibm.com Cc: yong.zhang0@gmail.com Cc: hch@infradead.org LKML-Reference: <20110127145855.23248.56933.stgit@localhost> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2011-01-31watchdog: Don't change watchdog state on read of sysctlMarcin Slusarz
Signed-off-by: Marcin Slusarz <marcin.slusarz@gmail.com> [ add {}'s to fix a warning ] Signed-off-by: Don Zickus <dzickus@redhat.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: <stable@kernel.org> LKML-Reference: <1296230433-6261-3-git-send-email-dzickus@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-01-31watchdog: Fix sysctl consistencyMarcin Slusarz
If it was not possible to enable watchdog for any cpu, switch watchdog_enabled back to 0, because it's visible via kernel.watchdog sysctl. Signed-off-by: Marcin Slusarz <marcin.slusarz@gmail.com> Signed-off-by: Don Zickus <dzickus@redhat.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: <stable@kernel.org> LKML-Reference: <1296230433-6261-2-git-send-email-dzickus@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-01-31watchdog: Fix broken nowatchdog logicMarcin Slusarz
Passing nowatchdog to kernel disables 2 things: creation of watchdog threads AND initialization of percpu watchdog_hrtimer. As hrtimers are initialized only at boot it's not possible to enable watchdog later - for me all watchdog threads started to eat 100% of CPU time, but they could just crash. Additionally, even if these threads would start properly, watchdog_disable_all_cpus was guarded by no_watchdog check, so you couldn't disable watchdog. To fix this, remove no_watchdog variable and use already existing watchdog_enabled variable. Signed-off-by: Marcin Slusarz <marcin.slusarz@gmail.com> [ removed another no_watchdog instance ] Signed-off-by: Don Zickus <dzickus@redhat.com> Cc: Stephane Eranian <eranian@google.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: <stable@kernel.org> LKML-Reference: <1296230433-6261-1-git-send-email-dzickus@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-01-31genirq: Fix affinity notifier falloutThomas Gleixner
The new code of commit cd7eab44e(genirq: Add IRQ affinity notifiers) references irq_desc.affinity which fails to compile with CONFIG_GENERIC_HARDIRQS_NO_DEPRECATED=y. Use irq_desc.irq_data.affinity instead. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Ben Hutchings <bhutchings@solarflare.com>
2011-01-31Fix prlimit64 for suid/sgid processesKacper Kornet
Since check_prlimit_permission always fails in the case of SUID/GUID processes, such processes are not able to read or set their own limits. This commit changes this by assuming that process can always read/change its own limits. Signed-off-by: Kacper Kornet <kornet@camk.edu.pl> Acked-by: Jiri Slaby <jslaby@suse.cz> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-01-27rtmutex: Simplify PI algorithm and make highest prio task get lockLai Jiangshan
In current rtmutex, the pending owner may be boosted by the tasks in the rtmutex's waitlist when the pending owner is deboosted or a task in the waitlist is boosted. This boosting is unrelated, because the pending owner does not really take the rtmutex. It is not reasonable. Example. time1: A(high prio) onwers the rtmutex. B(mid prio) and C (low prio) in the waitlist. time2 A release the lock, B becomes the pending owner A(or other high prio task) continues to run. B's prio is lower than A, so B is just queued at the runqueue. time3 A or other high prio task sleeps, but we have passed some time The B and C's prio are changed in the period (time2 ~ time3) due to boosting or deboosting. Now C has the priority higher than B. ***Is it reasonable that C has to boost B and help B to get the rtmutex? NO!! I think, it is unrelated/unneed boosting before B really owns the rtmutex. We should give C a chance to beat B and win the rtmutex. This is the motivation of this patch. This patch *ensures* only the top waiter or higher priority task can take the lock. How? 1) we don't dequeue the top waiter when unlock, if the top waiter is changed, the old top waiter will fail and go to sleep again. 2) when requiring lock, it will get the lock when the lock is not taken and: there is no waiter OR higher priority than waiters OR it is top waiter. 3) In any time, the top waiter is changed, the top waiter will be woken up. The algorithm is much simpler than before, no pending owner, no boosting for pending owner. Other advantage of this patch: 1) The states of a rtmutex are reduced a half, easier to read the code. 2) the codes become shorter. 3) top waiter is not dequeued until it really take the lock: they will retain FIFO when it is stolen. Not advantage nor disadvantage 1) Even we may wakeup multiple waiters(any time when top waiter changed), we hardly cause "thundering herd", the number of wokenup task is likely 1 or very little. 2) two APIs are changed. rt_mutex_owner() will not return pending owner, it will return NULL when the top waiter is going to take the lock. rt_mutex_next_owner() always return the top waiter. will not return NULL if we have waiters because the top waiter is not dequeued. I have fixed the code that use these APIs. need updated after this patch is accepted 1) Document/* 2) the testcase scripts/rt-tester/t4-l2-pi-deboost.tst Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com> LKML-Reference: <4D3012D5.4060709@cn.fujitsu.com> Reviewed-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2011-01-28Merge branch 'sched-fixes-for-linus' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip * 'sched-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: sched: Use rq->clock_task instead of rq->clock for correctly maintaining load averages sched: Fix/remove redundant cfs_rq checks sched: Fix sign under-flows in wake_affine
2011-01-27perf: Fix alloc_callchain_buffers()Eric Dumazet
Commit 927c7a9e92c4 ("perf: Fix race in callchains") introduced a mismatch in the sizing of struct callchain_cpus_entries. nr_cpu_ids must be used instead of num_possible_cpus(), or we might get out of bound memory accesses on some machines. Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: David Miller <davem@davemloft.net> Cc: Stephane Eranian <eranian@google.com> CC: stable@kernel.org LKML-Reference: <1295980851.3588.351.camel@edumazet-laptop> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-01-27sched: Avoid expensive initial update_cfs_load(), on UP tooPeter Zijlstra
Fix the build on UP. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Paul Turner <pjt@google.com> LKML-Reference: <20110122044852.102126037@google.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-01-27cred: Replace deprecated spinlock initializationThomas Gleixner
SPIN_LOCK_UNLOCK is deprecated. Use the lockdep capable variant instead. Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2011-01-27Merge commit 'v2.6.38-rc2' into core/lockingThomas Gleixner
Reason: Update to mainline before adding the locking cleanup Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
generated by cgit v1.2.3 (git 2.46.0) at 2025-07-19 08:26:11 +0000