linux/kernel/trace/rv, branch v6.17

rv: Fix missing mutex unlock in rv_register_monitor()

2025-09-15T06:36:35Z

If create_monitor_dir() fails, the function returns directly without releasing rv_interface_lock. This leaves the mutex locked and causes subsequent monitor registration attempts to deadlock. Fix it by making the error path jump to out_unlock, ensuring that the mutex is always released before returning. Fixes: 24cbfe18d55a ("rv: Merge struct rv_monitor_def into struct rv_monitor") Signed-off-by: Zhen Ni Reviewed-by: Gabriele Monaco Reviewed-by: Nam Cao Link: https://lore.kernel.org/r/20250903065112.1878330-1-zhen.ni@easystack.cn Signed-off-by: Gabriele Monaco

rv: Fix wrong type cast in enabled_monitors_next()

2025-09-15T06:36:35Z

Argument 'p' of enabled_monitors_next() is not a pointer to struct rv_monitor, it is actually a pointer to the list_head inside struct rv_monitor. Therefore it is wrong to cast 'p' to struct rv_monitor *. This wrong type cast has been there since the beginning. But it still worked because the list_head was the first field in struct rv_monitor_def. This is no longer true since commit 24cbfe18d55a ("rv: Merge struct rv_monitor_def into struct rv_monitor") moved the list_head, and this wrong type cast became a functional problem. Properly use container_of() instead. Fixes: 24cbfe18d55a ("rv: Merge struct rv_monitor_def into struct rv_monitor") Signed-off-by: Nam Cao Reviewed-by: Gabriele Monaco Link: https://lore.kernel.org/r/20250806120911.989365-1-namcao@linutronix.de Signed-off-by: Gabriele Monaco

rv: Support systems with time64-only syscalls

2025-09-15T06:36:27Z

Some systems (like 32-bit RISC-V) only have the 64-bit time_t versions of syscalls. So handle the 32-bit time_t version of those being undefined. Fixes: f74f8bb246cf ("rv: Add rtapp_sleep monitor") Closes: https://lore.kernel.org/oe-kbuild-all/202508160204.SsFyNfo6-lkp@intel.com Signed-off-by: Palmer Dabbelt Acked-by: Nam Cao Link: https://lore.kernel.org/r/20250804194518.97620-2-palmer@dabbelt.com Signed-off-by: Gabriele Monaco

Merge tag 'trace-v6.17' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace

2025-08-01T17:29:36Z

Pull tracing updates from Steven Rostedt: - Deprecate auto-mounting tracefs to /sys/kernel/debug/tracing When tracefs was first introduced back in 2014, the directory /sys/kernel/tracing was added and is the designated location to mount tracefs. To keep backward compatibility, tracefs was auto-mounted in /sys/kernel/debug/tracing as well. All distros now mount tracefs on /sys/kernel/tracing. Having it seen in two different locations has lead to various issues and inconsistencies. The VFS folks have to also maintain debugfs_create_automount() for this single user. It's been over 10 years. Tooling and scripts should start replacing the debugfs location with the tracefs one. The reason tracefs was created in the first place was to allow access to the tracing facilities without the need to configure debugfs into the kernel. Using tracefs should now be more robust. A new config is created: CONFIG_TRACEFS_AUTOMOUNT_DEPRECATED which is default y, so that the kernel is still built with the automount. This config allows those that want to remove the automount from debugfs to do so. When tracefs is accessed from /sys/kernel/debug/tracing, the following printk is triggerd: pr_warn("NOTICE: Automounting of tracing to debugfs is deprecated and will be removed in 2030\n"); This gives users another 5 years to fix their scripts. - Use queue_rcu_work() instead of call_rcu() for freeing event filters The number of filters to be free can be many depending on the number of events within an event system. Freeing them from softirq context can potentially cause undesired latency. Use the RCU workqueue to free them instead. - Remove pointless memory barriers in latency code Memory barriers were added to some of the latency code a long time ago with the idea of "making them visible", but that's not what memory barriers are for. They are to synchronize access between different variables. There was no synchronization here making them pointless. - Remove "__attribute__()" from the type field of event format When LLVM is used to compile the kernel with CONFIG_DEBUG_INFO_BTF=y and PAHOLE_HAS_BTF_TAG=y, some of the format fields get expanded with the following: field:const char * filename; offset:24; size:8; signed:0; Turns into: field:const char __attribute__((btf_type_tag("user"))) * filename; offset:24; size:8; signed:0; This confuses parsers. Add code to strip these tags from the strings. - Add eprobe config option CONFIG_EPROBE_EVENTS Eprobes were added back in 5.15 but were only enabled when another probe was enabled (kprobe, fprobe, uprobe, etc). The eprobes had no config option of their own. Add one as they should be a separate entity. It's default y to keep with the old kernels but still has dependencies on TRACING and HAVE_REGS_AND_STACK_ACCESS_API. - Add eprobe documentation When eprobes were added back in 5.15 no documentation was added to describe them. This needs to be rectified. - Replace open coded cpumask_next_wrap() in move_to_next_cpu() - Have preemptirq_delay_run() use off-stack CPU mask - Remove obsolete comment about pelt_cfs event DECLARE_TRACE() appends "_tp" to trace events now, but the comment above pelt_cfs still mentioned appending it manually. - Remove EVENT_FILE_FL_SOFT_MODE flag The SOFT_MODE flag was required when the soft enabling and disabling of trace events was first introduced. But there was a bug with this approach as it only worked for a single instance. When multiple users required soft disabling and disabling the code was changed to have a ref count. The SOFT_MODE flag is now set iff the ref count is non zero. This is redundant and just reading the ref count is good enough. - Fix typo in comment * tag 'trace-v6.17' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: Documentation: tracing: Add documentation about eprobes tracing: Have eprobes have their own config option tracing: Remove "__attribute__()" from the type field of event format tracing: Deprecate auto-mounting tracefs in debugfs tracing: Fix comment in trace_module_remove_events() tracing: Remove EVENT_FILE_FL_SOFT_MODE flag tracing: Remove pointless memory barriers tracing/sched: Remove obsolete comment on suffixes kernel: trace: preemptirq_delay_test: use offstack cpu mask tracing: Use queue_rcu_work() to free filters tracing: Replace opencoded cpumask_next_wrap() in move_to_next_cpu()

rv: Add opid per-cpu monitor

2025-07-28T20:47:35Z

Add a per-cpu monitor as part of the sched model: * opid: operations with preemption and irq disabled Monitor to ensure wakeup and need_resched occur with irq and preemption disabled or in irq handlers. Cc: Jonathan Corbet Cc: Masami Hiramatsu Cc: Ingo Molnar Cc: Peter Zijlstra Cc: Tomas Glozar Cc: Juri Lelli Cc: Clark Williams Cc: John Kacur Link: https://lore.kernel.org/20250728135022.255578-10-gmonaco@redhat.com Signed-off-by: Gabriele Monaco Acked-by: Nam Cao Tested-by: Nam Cao Signed-off-by: Steven Rostedt (Google)

rv: Add nrp and sssw per-task monitors

2025-07-28T20:47:34Z

Add 2 per-task monitors as part of the sched model: * nrp: need-resched preempts Monitor to ensure preemption requires need resched. * sssw: set state sleep and wakeup Monitor to ensure sched_set_state to sleepable leads to sleeping and sleeping tasks require wakeup. Cc: Ingo Molnar Cc: Jonathan Corbet Cc: Masami Hiramatsu Cc: Tomas Glozar Cc: Juri Lelli Cc: Clark Williams Cc: John Kacur Cc: Peter Zijlstra Link: https://lore.kernel.org/20250728135022.255578-9-gmonaco@redhat.com Signed-off-by: Gabriele Monaco Acked-by: Nam Cao Tested-by: Nam Cao Signed-off-by: Steven Rostedt (Google)

rv: Replace tss and sncid monitors with more complete sts

2025-07-28T20:47:34Z

The tss monitor currently guarantees task switches can happen only while scheduling, whereas the sncid monitor enforces scheduling occurs with interrupt disabled. Replace the monitors with a more comprehensive specification which implies both but also ensures that: * each scheduler call disable interrupts to switch * each task switch happens with interrupts disabled Cc: Ingo Molnar Cc: Jonathan Corbet Cc: Masami Hiramatsu Cc: Nam Cao Cc: Tomas Glozar Cc: Juri Lelli Cc: Clark Williams Cc: John Kacur Cc: Peter Zijlstra Link: https://lore.kernel.org/20250728135022.255578-8-gmonaco@redhat.com Signed-off-by: Gabriele Monaco Signed-off-by: Steven Rostedt (Google)

sched: Adapt sched tracepoints for RV task model

2025-07-28T20:47:34Z

Add the following tracepoint: * sched_set_need_resched(tsk, cpu, tif) Called when a task is set the need resched [lazy] flag Remove the unused ip parameter from sched_entry and sched_exit and alter sched_entry to have a value of preempt consistent with the one used in sched_switch. Also adapt all monitors using sched_{entry,exit} to avoid breaking build. These tracepoints are useful to describe the Linux task model and are adapted from the patches by Daniel Bristot de Oliveira (https://bristot.me/linux-task-model/). Cc: Ingo Molnar Cc: Peter Zijlstra Cc: Masami Hiramatsu Cc: Nam Cao Cc: Tomas Glozar Cc: Juri Lelli Cc: Clark Williams Cc: John Kacur Link: https://lore.kernel.org/20250728135022.255578-7-gmonaco@redhat.com Signed-off-by: Gabriele Monaco Signed-off-by: Steven Rostedt (Google)

rv: Retry when da monitor detects race conditions

2025-07-28T20:47:34Z

DA monitor can be accessed from multiple cores simultaneously, this is likely, for instance when dealing with per-task monitors reacting on events that do not always occur on the CPU where the task is running. This can cause race conditions where two events change the next state and we see inconsistent values. E.g.: [62] event_srs: 27: sleepable x sched_wakeup -> running (final) [63] event_srs: 27: sleepable x sched_set_state_sleepable -> sleepable [63] error_srs: 27: event sched_switch_suspend not expected in the state running In this case the monitor fails because the event on CPU 62 wins against the one on CPU 63, although the correct state should have been sleepable, since the task get suspended. Detect if the current state was modified by using try_cmpxchg while storing the next value. If it was, try again reading the current state. After a maximum number of failed retries, react by calling a special tracepoint, print on the console and reset the monitor. Remove the functions da_monitor_curr_state() and da_monitor_set_state() as they only hide the underlying implementation in this case. Monitors where this type of condition can occur must be able to account for racing events in any possible order, as we cannot know the winner. Cc: Ingo Molnar Cc: Masami Hiramatsu Cc: Tomas Glozar Cc: Juri Lelli Cc: Clark Williams Cc: John Kacur Cc: Peter Zijlstra Link: https://lore.kernel.org/20250728135022.255578-6-gmonaco@redhat.com Signed-off-by: Gabriele Monaco Reviewed-by: Nam Cao Signed-off-by: Steven Rostedt (Google)

rv: Adjust monitor dependencies

2025-07-28T20:47:34Z

RV monitors relying on the preemptirqs tracepoints are set as dependent on PREEMPT_TRACER and IRQSOFF_TRACER. In fact, those configurations do enable the tracepoints but are not the minimal configurations enabling them, which are TRACE_PREEMPT_TOGGLE and TRACE_IRQFLAGS (not selectable manually). Set TRACE_PREEMPT_TOGGLE and TRACE_IRQFLAGS as dependencies for monitors. Cc: Masami Hiramatsu Cc: Ingo Molnar Cc: Peter Zijlstra Cc: Tomas Glozar Cc: Juri Lelli Cc: Clark Williams Cc: John Kacur Link: https://lore.kernel.org/20250728135022.255578-5-gmonaco@redhat.com Fixes: fbe6c09b7eb4 ("rv: Add scpd, snep and sncid per-cpu monitors") Acked-by: Nam Cao Signed-off-by: Gabriele Monaco Signed-off-by: Steven Rostedt (Google)