To prepare for optimizing the rearming of enqueued timers, switch to the
linked timerqueue. That allows to check whether the new expiry time changes
the position of the timer in the RB tree or not, by checking the new expiry
time against the previous and the next timers expiry.
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260224163431.806643179@kernel.org
All 'u8' flags are true booleans, so make it entirely clear that these can
only contain true or false.
This is especially true for hrtimer::state, which has a historical leftover
of using the state with bitwise operations. That was used in the early
hrtimer implementation with several bits, but then converted to a boolean
state. But that conversion missed to replace the bit OR and bit check
operations all over the place, which creates suboptimal code. As of today
'state' is a misnomer because it's only purpose is to reflect whether the
timer is enqueued into the RB-tree or not. Rename it to 'is_queued' and
make all operations on it boolean.
This reduces text size from 8926 to 8732 bytes.
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260224163430.542427240@kernel.org
This reverts commit f590308536 ("timer debug: Hide kernel addresses via
%pK in /proc/timer_list")
The timer list helper SEQ_printf() uses either the real seq_printf() for
procfs output or vprintk() to print to the kernel log, when invoked from
SysRq-q. It uses %pK for printing pointers.
In the past %pK was prefered over %p as it would not leak raw pointer
values into the kernel log. Since commit ad67b74d24 ("printk: hash
addresses printed with %p") the regular %p has been improved to avoid this
issue.
Furthermore, restricted pointers ("%pK") were never meant to be used
through printk(). They can still unintentionally leak raw pointers or
acquire sleeping looks in atomic contexts.
Switch to the regular pointer formatting which is safer, easier to reason
about and sufficient here.
Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/lkml/20250113171731-dc10e3c1-da64-4af0-b767-7c7070468023@linutronix.de/
Link: https://lore.kernel.org/all/20250311-restricted-pointers-timer-v1-1-6626b91e54ab@linutronix.de
The nohz mode field tells about low resolution nohz mode or high
resolution nohz mode but it doesn't tell about high resolution non-nohz
mode.
In order to retrieve the latter state, tick_cancel_sched_timer() must
fiddle with struct hrtimer's internals to guess if the tick has been
initialized in high resolution.
Move instead the nohz mode field information into the tick flags and
provide two new bits: one to know if the tick is in nohz mode and
another one to know if the tick is in high resolution. The combination
of those two flags provides all the needed informations to determine
which of the three tick modes is running.
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20240225225508.11587-14-frederic@kernel.org
The individual bitfields of struct tick_sched must be modified from
IRQs disabled places, otherwise local modifications can race due to them
sharing the same memory storage.
The recent move of the "got_idle_tick" bitfield to its own storage shows
that the use of these bitfields, as pretty as they look, can be as much
error prone.
In order to avoid future issues of the like and make sure that those
bitfields are safely accessed, move those flags to an explicit mask
along with a mutator function performing the basic IRQs disabled sanity
check.
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20240225225508.11587-13-frederic@kernel.org
Use the "%ps" printk format string to resolve symbol names.
This works on all platforms, including ia64, ppc64 and parisc64 on which
one needs to dereference pointers to function descriptors instead of
function pointers.
Signed-off-by: Helge Deller <deller@gmx.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20201104163401.GA3984@ls3530.fritz.box
Pull timers and timekeeping updates from Thomas Gleixner:
- Core infrastucture work for Y2038 to address the COMPAT interfaces:
+ Add a new Y2038 safe __kernel_timespec and use it in the core
code
+ Introduce config switches which allow to control the various
compat mechanisms
+ Use the new config switch in the posix timer code to control the
32bit compat syscall implementation.
- Prevent bogus selection of CPU local clocksources which causes an
endless reselection loop
- Remove the extra kthread in the clocksource code which has no value
and just adds another level of indirection
- The usual bunch of trivial updates, cleanups and fixlets all over the
place
- More SPDX conversions
* 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (24 commits)
clocksource/drivers/mxs_timer: Switch to SPDX identifier
clocksource/drivers/timer-imx-tpm: Switch to SPDX identifier
clocksource/drivers/timer-imx-gpt: Switch to SPDX identifier
clocksource/drivers/timer-imx-gpt: Remove outdated file path
clocksource/drivers/arc_timer: Add comments about locking while read GFRC
clocksource/drivers/mips-gic-timer: Add pr_fmt and reword pr_* messages
clocksource/drivers/sprd: Fix Kconfig dependency
clocksource: Move inline keyword to the beginning of function declarations
timer_list: Remove unused function pointer typedef
timers: Adjust a kernel-doc comment
tick: Prefer a lower rating device only if it's CPU local device
clocksource: Remove kthread
time: Change nanosleep to safe __kernel_* types
time: Change types to new y2038 safe __kernel_* types
time: Fix get_timespec64() for y2038 safe compat interfaces
time: Add new y2038 safe __kernel_timespec
posix-timers: Make compat syscalls depend on CONFIG_COMPAT_32BIT_TIME
time: Introduce CONFIG_COMPAT_32BIT_TIME
time: Introduce CONFIG_64BIT_TIME in architectures
compat: Enable compat_get/put_timespec64 always
...
Variant of proc_create_data that directly take a struct seq_operations
argument + a private state size and drastically reduces the boilerplate
code in the callers.
All trivial callers converted over.
Signed-off-by: Christoph Hellwig <hch@lst.de>
On systems with a large number of CPUs, running sysrq-<q> can cause
watchdog timeouts. There are two slow sections of code in the sysrq-<q>
path in timer_list.c.
1. print_active_timers() - This function is called by print_cpu() and
contains a slow goto loop. On a machine with hundreds of CPUs, this
loop took approximately 100ms for the first CPU in a NUMA node.
(Subsequent CPUs in the same node ran much quicker.) The total time
to print all of the CPUs is ultimately long enough to trigger the
soft lockup watchdog.
2. print_tickdevice() - This function outputs a large amount of textual
information. This function also took approximately 100ms per CPU.
Since sysrq-<q> is not a performance critical path, there should be no
harm in touching the nmi watchdog in both slow sections above. Touching
it in just one location was insufficient on systems with hundreds of
CPUs as occasional timeouts were still observed during testing.
This issue was observed on an Oracle T7 machine with 128 CPUs, but I
anticipate it may affect other systems with similarly large numbers of
CPUs.
Signed-off-by: Tom Hromatka <tom.hromatka@oracle.com>
Reviewed-by: Rob Gardner <rob.gardner@oracle.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
This was entirely automated, using the script by Al:
PATT='^[[:blank:]]*#[[:blank:]]*include[[:blank:]]*<asm/uaccess.h>'
sed -i -e "s!$PATT!#include <linux/uaccess.h>!" \
$(git grep -l "$PATT"|grep -v ^include/linux/uaccess.h)
to do the replacement at the end of the merge window.
Requested-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
If CONFIG_TIME_LOW_RES is enabled we add a jiffie to the relative timeout to
prevent short sleeps, but we do not account for that in interfaces which
retrieve the remaining time.
Helge observed that timerfd can return a remaining time larger than the
relative timeout. That's not expected and breaks userland test programs.
Store the information that the timer was armed relative and provide functions
to adjust the remaining time. To avoid bloating the hrtimer struct make state
a u8, which as a bonus results in better code on x86 at least.
Reported-and-tested-by: Helge Deller <deller@gmx.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: John Stultz <john.stultz@linaro.org>
Cc: linux-m68k@lists.linux-m68k.org
Cc: dhowells@redhat.com
Cc: stable@vger.kernel.org
Link: http://lkml.kernel.org/r/20160114164159.273328486@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
I noticed for non-monotonic timers in timer_list, some of the
output looked a little confusing.
For example:
#1: <0000000000000000>, posix_timer_fn, S:01, hrtimer_start_range_ns, leap-a-day/2360
# expires at 1434412800000000000-1434412800000000000 nsecs [in 1434410725062375469 to 1434410725062375469 nsecs]
You'll note the relative time till the expiration "[in xxx to
yyy nsecs]" is incorrect. This is because its printing the delta
between CLOCK_MONOTONIC time to the CLOCK_REALTIME expiration.
This patch fixes this issue by adding the clock offset to the
"now" time which we use to calculate the delta.
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Daniel Bristot de Oliveira <bristot@redhat.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Jiri Bohac <jbohac@suse.cz>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Shuah Khan <shuahkh@osg.samsung.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
