linux/kernel/time, branch v5.7

proc, time/namespace: Show clock symbolic names in /proc/pid/timens_offsets

2020-04-16T10:10:54Z

Michael Kerrisk suggested to replace numeric clock IDs with symbolic names. Now the content of these files looks like this: $ cat /proc/774/timens_offsets monotonic 864000 0 boottime 1728000 0 For setting offsets, both representations of clocks (numeric and symbolic) can be used. As for compatibility, it is acceptable to change things as long as userspace doesn't care. The format of timens_offsets files is very new and there are no userspace tools yet which rely on this format. But three projects crun, util-linux and criu rely on the interface of setting time offsets and this is why it's required to continue supporting the numeric clock IDs on write. Fixes: 04a8682a71be ("fs/proc: Introduce /proc/pid/timens_offsets") Suggested-by: Michael Kerrisk Signed-off-by: Andrei Vagin Signed-off-by: Thomas Gleixner Tested-by: Michael Kerrisk Acked-by: Michael Kerrisk Cc: Andrew Morton Cc: Eric W. Biederman Cc: Dmitry Safonov <0x7f454c46@gmail.com> Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/20200411154031.642557-1-avagin@gmail.com

time/namespace: Fix time_for_children symlink

2020-04-07T10:37:21Z

Looking at the contents of the /proc/PID/ns/time_for_children symlink shows an anomaly: $ ls -l /proc/self/ns/* |awk '{print $9, $10, $11}' ... /proc/self/ns/pid -> pid:[4026531836] /proc/self/ns/pid_for_children -> pid:[4026531836] /proc/self/ns/time -> time:[4026531834] /proc/self/ns/time_for_children -> time_for_children:[4026531834] /proc/self/ns/user -> user:[4026531837] ... The reference for 'time_for_children' should be a 'time' namespace, just as the reference for 'pid_for_children' is a 'pid' namespace. In other words, the above time_for_children link should read: /proc/self/ns/time_for_children -> time:[4026531834] Fixes: 769071ac9f20 ("ns: Introduce Time Namespace") Signed-off-by: Michael Kerrisk Signed-off-by: Thomas Gleixner Reviewed-by: Dmitry Safonov Acked-by: Christian Brauner Acked-by: Andrei Vagin Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/a2418c48-ed80-3afe-116e-6611cb799557@gmail.com

hrtimer: Don't dereference the hrtimer pointer after the callback

2020-04-01T11:20:14Z

A hrtimer can be released in its callback, but lockdep_hrtimer_exit() dereferences the pointer after the callback returns, i.e. a potential use after free. Retrieve the context in which the hrtimer expires before the callback is invoked and use it in lockdep_hrtimer_exit(). Fixes: 40db173965c0 ("lockdep: Add hrtimer context tracing bits") Reported-by: syzbot+62c155c276e580cfb606@syzkaller.appspotmail.com Signed-off-by: Sebastian Andrzej Siewior Signed-off-by: Thomas Gleixner Link: https://lkml.kernel.org/r/20200331201849.fkp2siy3vcdqvqlz@linutronix.de

Merge tag 'timers-core-2020-03-30' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2020-03-31T01:51:47Z

Pull timekeeping and timer updates from Thomas Gleixner: "Core: - Consolidation of the vDSO build infrastructure to address the difficulties of cross-builds for ARM64 compat vDSO libraries by restricting the exposure of header content to the vDSO build. This is achieved by splitting out header content into separate headers. which contain only the minimaly required information which is necessary to build the vDSO. These new headers are included from the kernel headers and the vDSO specific files. - Enhancements to the generic vDSO library allowing more fine grained control over the compiled in code, further reducing architecture specific storage and preparing for adopting the generic library by PPC. - Cleanup and consolidation of the exit related code in posix CPU timers. - Small cleanups and enhancements here and there Drivers: - The obligatory new drivers: Ingenic JZ47xx and X1000 TCU support - Correct the clock rate of PIT64b global clock - setup_irq() cleanup - Preparation for PWM and suspend support for the TI DM timer - Expand the fttmr010 driver to support ast2600 systems - The usual small fixes, enhancements and cleanups all over the place" * tag 'timers-core-2020-03-30' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (80 commits) Revert "clocksource/drivers/timer-probe: Avoid creating dead devices" vdso: Fix clocksource.h macro detection um: Fix header inclusion arm64: vdso32: Enable Clang Compilation lib/vdso: Enable common headers arm: vdso: Enable arm to use common headers x86/vdso: Enable x86 to use common headers mips: vdso: Enable mips to use common headers arm64: vdso32: Include common headers in the vdso library arm64: vdso: Include common headers in the vdso library arm64: Introduce asm/vdso/processor.h arm64: vdso32: Code clean up linux/elfnote.h: Replace elf.h with UAPI equivalent scripts: Fix the inclusion order in modpost common: Introduce processor.h linux/ktime.h: Extract common header for vDSO linux/jiffies.h: Extract common header for vDSO linux/time64.h: Extract common header for vDSO linux/time32.h: Extract common header for vDSO linux/time.h: Extract common header for vDSO ...

Merge branch 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2020-03-30T23:17:15Z

Pull locking updates from Ingo Molnar: "The main changes in this cycle were: - Continued user-access cleanups in the futex code. - percpu-rwsem rewrite that uses its own waitqueue and atomic_t instead of an embedded rwsem. This addresses a couple of weaknesses, but the primary motivation was complications on the -rt kernel. - Introduce raw lock nesting detection on lockdep (CONFIG_PROVE_RAW_LOCK_NESTING=y), document the raw_lock vs. normal lock differences. This too originates from -rt. - Reuse lockdep zapped chain_hlocks entries, to conserve RAM footprint on distro-ish kernels running into the "BUG: MAX_LOCKDEP_CHAIN_HLOCKS too low!" depletion of the lockdep chain-entries pool. - Misc cleanups, smaller fixes and enhancements - see the changelog for details" * 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (55 commits) fs/buffer: Make BH_Uptodate_Lock bit_spin_lock a regular spinlock_t thermal/x86_pkg_temp: Make pkg_temp_lock a raw_spinlock_t Documentation/locking/locktypes: Minor copy editor fixes Documentation/locking/locktypes: Further clarifications and wordsmithing m68knommu: Remove mm.h include from uaccess_no.h x86: get rid of user_atomic_cmpxchg_inatomic() generic arch_futex_atomic_op_inuser() doesn't need access_ok() x86: don't reload after cmpxchg in unsafe_atomic_op2() loop x86: convert arch_futex_atomic_op_inuser() to user_access_begin/user_access_end() objtool: whitelist __sanitizer_cov_trace_switch() [parisc, s390, sparc64] no need for access_ok() in futex handling sh: no need of access_ok() in arch_futex_atomic_op_inuser() futex: arch_futex_atomic_op_inuser() calling conventions change completion: Use lockdep_assert_RT_in_threaded_ctx() in complete_all() lockdep: Add posixtimer context tracing bits lockdep: Annotate irq_work lockdep: Add hrtimer context tracing bits lockdep: Introduce wait-type checks completion: Use simple wait queues sched/swait: Prepare usage in completions ...

Merge branch 'for-mingo' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu into core/rcu

2020-03-24T09:10:09Z

Pull RCU changes from Paul E. McKenney: - Make kfree_rcu() use kfree_bulk() for added performance - RCU updates - Callback-overload handling updates - Tasks-RCU KCSAN and sparse updates - Locking torture test and RCU torture test updates - Documentation updates - Miscellaneous fixes Signed-off-by: Ingo Molnar

lockdep: Add posixtimer context tracing bits

2020-03-21T15:00:25Z

Splitting run_posix_cpu_timers() into two parts is work in progress which is stuck on other entry code related problems. The heavy lifting which involves locking of sighand lock will be moved into task context so the necessary execution time is burdened on the task and not on interrupt context. Until this work completes lockdep with the spinlock nesting rules enabled would emit warnings for this known context. Prevent it by setting "->irq_config = 1" for the invocation of run_posix_cpu_timers() so lockdep does not complain when sighand lock is acquried. This will be removed once the split is completed. Signed-off-by: Sebastian Andrzej Siewior Signed-off-by: Thomas Gleixner Signed-off-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/20200321113242.751182723@linutronix.de

lockdep: Annotate irq_work

2020-03-21T15:00:24Z

Mark irq_work items with IRQ_WORK_HARD_IRQ which should be invoked in hardirq context even on PREEMPT_RT. IRQ_WORK without this flag will be invoked in softirq context on PREEMPT_RT. Set ->irq_config to 1 for the IRQ_WORK items which are invoked in softirq context so lockdep knows that these can safely acquire a spinlock_t. Signed-off-by: Sebastian Andrzej Siewior Signed-off-by: Thomas Gleixner Signed-off-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/20200321113242.643576700@linutronix.de

lockdep: Add hrtimer context tracing bits

2020-03-21T15:00:24Z

Set current->irq_config = 1 for hrtimers which are not marked to expire in hard interrupt context during hrtimer_init(). These timers will expire in softirq context on PREEMPT_RT. Setting this allows lockdep to differentiate these timers. If a timer is marked to expire in hard interrupt context then the timer callback is not supposed to acquire a regular spinlock instead of a raw_spinlock in the expiry callback. Signed-off-by: Sebastian Andrzej Siewior Signed-off-by: Thomas Gleixner Signed-off-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/20200321113242.534508206@linutronix.de

timekeeping: Split jiffies seqlock

2020-03-21T15:00:23Z

seqlock consists of a sequence counter and a spinlock_t which is used to serialize the writers. spinlock_t is substituted by a "sleeping" spinlock on PREEMPT_RT enabled kernels which breaks the usage in the timekeeping code as the writers are executed in hard interrupt and therefore non-preemptible context even on PREEMPT_RT. The spinlock in seqlock cannot be unconditionally replaced by a raw_spinlock_t as many seqlock users have nesting spinlock sections or other code which is not suitable to run in truly atomic context on RT. Instead of providing a raw_seqlock API for a single use case, open code the seqlock for the jiffies use case and implement it with a raw_spinlock_t and a sequence counter. Signed-off-by: Thomas Gleixner Signed-off-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/20200321113242.120587764@linutronix.de