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2011-05-24posix-timers: RCU conversionEric Dumazet
Ben Nagy reported a scalability problem with KVM/QEMU that hit very hard a single spinlock (idr_lock) in posix-timers code, on its 48 core machine. Even on a 16 cpu machine (2x4x2), a single test can show 98% of cpu time used in ticket_spin_lock, from lock_timer Ref: http://www.spinics.net/lists/kvm/msg51526.html Switching to RCU is quite easy, IDR being already RCU ready. idr_lock should be locked only for an insert/delete, not a lookup. Benchmark on a 2x4x2 machine, 16 processes calling timer_gettime(). Before : real 1m18.669s user 0m1.346s sys 1m17.180s After : real 0m3.296s user 0m1.366s sys 0m1.926s Reported-by: Ben Nagy <ben@iagu.net> Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com> Tested-by: Ben Nagy <ben@iagu.net> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Avi Kivity <avi@redhat.com> Cc: John Stultz <johnstul@us.ibm.com> Cc: Richard Cochran <richard.cochran@omicron.at> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2011-05-23hrtimers: Avoid touching inactive timer basesThomas Gleixner
Instead of iterating over all possible timer bases avoid it by marking the active bases in the cpu base. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Peter Zijlstra <peterz@infradead.org>
2011-03-31Fix common misspellingsLucas De Marchi
Fixes generated by 'codespell' and manually reviewed. Signed-off-by: Lucas De Marchi <lucas.demarchi@profusion.mobi>
2011-02-21timers: Export CLOCK_BOOTTIME via the posix timers interfaceJohn Stultz
This patch exports CLOCK_BOOTTIME through the posix timers interface CC: Jamie Lokier <jamie@shareable.org> CC: Thomas Gleixner <tglx@linutronix.de> CC: Alexander Shishkin <virtuoso@slind.org> CC: Arve Hjønnevåg <arve@android.com> Signed-off-by: John Stultz <john.stultz@linaro.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>
2011-02-02posix-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: 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-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: 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>
2010-10-21posix-timers: Annotate lock_timer()Namhyung Kim
lock_timer() conditionally grabs it_lock in case of returning non-NULL but unlock_timer() releases it unconditionally. This leads sparse to complain about the lock context imbalance. Rename and wrap lock_timer using __cond_lock() macro to make sparse happy. Signed-off-by: Namhyung Kim <namhyung@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2010-07-23posix_timer: Move copy_to_user(created_timer_id) down in timer_create()Andrey Vagin
According to Oleg Nesterov: We can move copy_to_user(created_timer_id) down after "if (timer_event_spec)" block too. (but before CLOCK_DISPATCH(), of course). Signed-off-by: Andrey Vagin <avagin@openvz.org> Cc: Oleg Nesterov <oleg@tv-sign.ru> Cc: Pavel Emelyanov <xemul@openvz.org> Cc: Stanislaw Gruszka <sgruszka@redhat.com> Cc: Andrey Vagin <avagin@openvz.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2010-05-27posix_timer: Fix error path in timer_createAndrey Vagin
Move CLOCK_DISPATCH(which_clock, timer_create, (new_timer)) after all posible EFAULT erros. *_timer_create may allocate/get resources. (for example posix_cpu_timer_create does get_task_struct) [ tglx: fold the remove crappy comment patch into this ] Signed-off-by: Andrey Vagin <avagin@openvz.org> Cc: Oleg Nesterov <oleg@tv-sign.ru> Cc: Pavel Emelyanov <xemul@openvz.org> Cc: <stable@kernel.org> Reviewed-by: Stanislaw Gruszka <sgruszka@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2010-02-05posix-timers.c: Don't export local functionsH Hartley Sweeten
Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2009-08-21time: Introduce CLOCK_REALTIME_COARSEjohn stultz
After talking with some application writers who want very fast, but not fine-grained timestamps, I decided to try to implement new clock_ids to clock_gettime(): CLOCK_REALTIME_COARSE and CLOCK_MONOTONIC_COARSE which returns the time at the last tick. This is very fast as we don't have to access any hardware (which can be very painful if you're using something like the acpi_pm clocksource), and we can even use the vdso clock_gettime() method to avoid the syscall. The only trade off is you only get low-res tick grained time resolution. This isn't a new idea, I know Ingo has a patch in the -rt tree that made the vsyscall gettimeofday() return coarse grained time when the vsyscall64 sysctrl was set to 2. However this affects all applications on a system. With this method, applications can choose the proper speed/granularity trade-off for themselves. Signed-off-by: John Stultz <johnstul@us.ibm.com> Cc: Andi Kleen <andi@firstfloor.org> Cc: nikolag@ca.ibm.com Cc: Darren Hart <dvhltc@us.ibm.com> Cc: arjan@infradead.org Cc: jonathan@jonmasters.org LKML-Reference: <1250734414.6897.5.camel@localhost.localdomain> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2009-08-04posix-timers: Fix oops in clock_nanosleep() with CLOCK_MONOTONIC_RAWHiroshi Shimamoto
Prevent calling do_nanosleep() with clockid CLOCK_MONOTONIC_RAW, it may cause oops, such as NULL pointer dereference. Signed-off-by: Hiroshi Shimamoto <h-shimamoto@ct.jp.nec.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: John Stultz <johnstul@us.ibm.com> Cc: <stable@kernel.org> LKML-Reference: <4A764FF3.50607@ct.jp.nec.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-01-14[CVE-2009-0029] System call wrappers part 05Heiko Carstens
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
2008-12-25Merge branches 'timers/clocksource', 'timers/hpet', 'timers/hrtimers', ↵Ingo Molnar
'timers/nohz', 'timers/ntp', 'timers/posixtimers' and 'timers/rtc' into timers/core
2008-12-20Null pointer deref with hrtimer_try_to_cancel()Thomas Gleixner
Impact: Prevent kernel crash with posix timer clockid CLOCK_MONOTONIC_RAW commit 2d42244ae71d6c7b0884b5664cf2eda30fb2ae68 (clocksource: introduce CLOCK_MONOTONIC_RAW) introduced a new clockid, which is only available to read out the raw not NTP adjusted system time. The above commit did not prevent that a posix timer can be created with that clockid. The timer_create() syscall succeeds and initializes the timer to a non existing hrtimer base. When the timer is deleted either by timer_delete() or by the exit() cleanup the kernel crashes. Prevent the creation of timers for CLOCK_MONOTONIC_RAW by setting the posix clock function to no_timer_create which returns an error code. Reported-and-tested-by: Eric Sesterhenn <snakebyte@gmx.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-12-12posix-timers: check ->it_signal instead of ->it_pid to validate the timerOleg Nesterov
Impact: clean up, speed up ->it_pid (was ->it_process) has also a special meaning: if it is NULL, the timer is under deletion or it wasn't initialized yet. We can check ->it_signal != NULL instead, this way we can - simplify sys_timer_create() a bit - remove yet another check from lock_timer() - move put_pid(->it_pid) into release_posix_timer() which runs outside of ->it_lock Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-12-12posix-timers: use "struct pid*" instead of "struct task_struct*"Oleg Nesterov
Impact: restructure, clean up code k_itimer holds the ref to the ->it_process until sys_timer_delete(). This allows to pin up to RLIMIT_SIGPENDING dead task_struct's. Change the code to use "struct pid *" instead. The patch doesn't kill ->it_process, it places ->it_pid into the union. ->it_process is still used by do_cpu_nanosleep() as before. It would be trivial to change the nanosleep code as well, but since it uses it_process in a special way I think it is better to keep this field for grep. The patch bloats the kernel by 104 bytes and it also adds the new pointer, ->it_signal, to k_itimer. It is used by lock_timer() to verify that the found timer was not created by another process. It is not clear why do we use the global database (and thus the global idr_lock) for posix timers. We still need the signal_struct->posix_timers which contains all useable timers, perhaps it is better to use some form of per-process array instead. Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-10-22Merge branch 'timers/range-hrtimers' into v28-range-hrtimers-for-linus-v2Thomas Gleixner
Conflicts: kernel/time/tick-sched.c Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-10-20Merge branches 'timers/clocksource', 'timers/hrtimers', 'timers/nohz', ↵Thomas Gleixner
'timers/ntp', 'timers/posixtimers' and 'timers/debug' into v28-timers-for-linus
2008-10-17Merge commit 'linus/master' into merge-linusArjan van de Ven
Conflicts: arch/x86/kvm/i8254.c
2008-10-02fix error-path NULL deref in alloc_posix_timer()Dan Carpenter
Found by static checker (http://repo.or.cz/w/smatch.git). Signed-off-by: Dan Carpenter <error27@gmail.com> Acked-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-09-24posix-timers: lock_timer: make it readableOleg Nesterov
Cleanup. Imho makes the code much more understandable. At least this patch lessens both the source and compiled code. Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru> Cc: mingo@elte.hu Cc: Roland McGrath <roland@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-09-24posix-timers: lock_timer: kill the bogus ->it_id checkOleg Nesterov
lock_timer() checks that the timer found by idr_find(timer_id) has ->it_id == timer_id. This buys nothing. This check can fail only if sys_timer_create() unlocked idr_lock after idr_get_new(), but didn't set ->it_id = new_timer_id yet. But in that case ->it_process == NULL so lock_timer() can't succeed anyway. Also remove a couple of unneeded typecasts. Note that with or without this patch we have a small problem. sys_timer_create() doesn't ensure that the result of setting (say) ->it_sigev_notify must be visible if lock_timer() succeeds. Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru> Cc: mingo@elte.hu Cc: Roland McGrath <roland@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-09-24posix-timers: kill ->it_sigev_signo and ->it_sigev_valueOleg Nesterov
With the recent changes ->it_sigev_signo and ->it_sigev_value are only used in sys_timer_create(), kill them. Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru> Cc: mingo@elte.hu Cc: Roland McGrath <roland@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-09-24posix-timers: sys_timer_create: cleanup the error handlingOleg Nesterov
Cleanup. - sys_timer_create() is big and complicated. The code above the "out:" label relies on the fact that "error" must be == 0. This is not very robust, make the code more explicit. Remove the unneeded initialization of error. - If idr_get_new() succeeds (as it normally should), we check the returned value twice. Move the "-EAGAIN" check under "if (error)". Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru> Cc: mingo@elte.hu Cc: Roland McGrath <roland@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-09-24posix-timers: move the initialization of timer->sigq from send to create pathOleg Nesterov
posix_timer_event() always populates timer->sigq with the same numbers, move this code into sys_timer_create(). Note that with this patch we can kill it_sigev_signo and it_sigev_value. Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru> Cc: mingo@elte.hu Cc: Roland McGrath <roland@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-09-24posix-timers: sys_timer_create: simplify and s/tasklist/rcu/Oleg Nesterov
- Change the code to do rcu_read_lock() instead of taking tasklist_lock, it is safe to get_task_struct(p) if p was found under RCU. However, now we must not use process's sighand/signal, they may be NULL. We can use current->sighand/signal instead, this "process" must belong to the current's thread-group. - Factor out the common code for 2 "if (timer_event_spec)" branches, the !timer_event_spec case can use current too. - use spin_lock_irq() instead of _irqsave(), kill "flags". Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru> Cc: mingo@elte.hu Cc: Roland McGrath <roland@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-09-24posix-timers: sys_timer_create: remove the buggy PF_EXITING checkOleg Nesterov
sys_timer_create() return -EINVAL if the target thread has PF_EXITING. This doesn't really make sense, the sub-thread can die right after unlock. And in fact, this is just wrong. Without SIGEV_THREAD_ID good_sigevent() returns ->group_leader, and it is very possible that the leader is already dead. This is OK, we shouldn't return the error in this case. Remove this check and the comment. Note that the "process" was found under tasklist_lock, it must have ->sighand != NULL. Also, remove a couple of unneeded initializations. Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru> Cc: mingo@elte.hu Cc: Roland McGrath <roland@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-09-24posix-timers: always do get_task_struct(timer->it_process)Oleg Nesterov
Change the code to get/put timer->it_process regardless of SIGEV_THREAD_ID. This streamlines the create/destroy paths and allows us to simplify the usage of exit_itimers() in de_thread(). Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru> Cc: mingo@elte.hu Cc: Roland McGrath <roland@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-09-24posix-timers: don't switch to ->group_leader if ->it_process diesOleg Nesterov
posix_timer_event() drops SIGEV_THREAD_ID and switches to ->group_leader if send_sigqueue() fails. This is not very useful and doesn't work reliably. send_sigqueue() can only fail if ->it_process is dead. But it can die before it dequeues the SI_TIMER signal, in that case the timer stops anyway. Remove this code. I guess it was needed a long ago to ensure that the timer is not destroyed when when its creator thread dies. Q: perhaps it makes sense to change sys_timer_settime() to return an error if ->it_process is dead? Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru> Cc: mingo@elte.hu Cc: Roland McGrath <roland@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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